Stone managementEdmond

WorkupImagingRenal fxn scanMetabolic workup: Bld & UrineTxn of metabolic stone

Review of modality of stone txnESWL URSLPCNLLap/open renal stone surgeryLap/open ureteric stone surgeryDissolution therapy

Treatment of Renal stoneStaghorn stoneUpper and mid pole stone Lower pole stoneRenal pelvis stone with upper ureter extensionCalyceal stoneHorsehoe kidney stonePelvic kidney stoneBilateral renal stoneStone with PUJO

Treatment of ureteric stoneMx of renal colicRelief obstructionUreteric stone: upper , mid , lowerMETBilateral ureteric stone

Epidmiology Epidemiology Caucasian of renal stone 10%, rising trendRecurrence of renal stone within 1 year 10%Recurrence of renal stone within 10 years 50%Calcium stone - 75% : Ca oxalate , Ca phosphateNon-calcium stone 25% Infection stoneMagnesium ammonium phosphate (10%)Carbonate apatiteAmmonium urateAmmonium urate stones form when a urease-producing infection occurs in patients with urine that is supersaturated with uric acid/urateUric acid (10%) : 20% of gout have uric acid stoneRare stone that is radiolucent : Indinavir (HIV med), triamterene (K sparing diuretic) Cystine stone (renal tubular defect 1%)

Risk factors

Why does the stone form?Imbalance between stone promoter and inhibitorSaturation below solubility product stone will not formSaturation above solubility product crystal growth can be prevented by increased inhibitorsSaturation above formation product stone forms despite inhibitorsUrine concentration btw solubility product & formation product metastableUrine concentration above formation product supersaturatedInhibitor of crystallization : Mg , GAG, Tamm-Horsfall (?) protein, citrate

Phases of stone formation: Nucleation: crystal nuclei occur on surface of epithelial cell or on other crystalAggregation : Crystal nuclei form into clumps

Risk factorsAge (younger age group, peak at 40)Sex (male)Strong family history of stone formationRace (Caucasian > black > Asian)Positive family historyDiet: obesity High animal protein (high ca, uric & oxalate, low pH, low citrate)High salt (hypercalciuria)High Calcium intake is protectiveVit D (increase instestinal Ca absorption) Vit C (cause hyperoxaluria) Occupation: sedentary lifestyleGoutLow fluid intake (urine output

AgeGenderSeason/climateFluid IntakeStress/dietOccupationMobilityMetabolic disordersGenetic disordersAnatomical abnormalityFamily historyRisk Factors for Calcium Stone-Formation

Urinary Risk Factors for Stone-Formation

Low urine volume (4mg/kg/24hrs)Hyperoxaluria (40mg/24hrs)Hyperuricosuria(>600mg/24hrs)Hypocitraturia(

What are the risk factors for recurrent stone formation?Diseases associated with stone formation Hyperparathyroidism Renal tubular acidosis (partial/complete) Cystinuria Primary hyperoxaluria Jejuno-ileal bypass Crohns disease Intestinal resection Malabsorptive conditions Sarcoidosis

What are the risk factors for recurrent stone formation?Anatomical abnormalities associated with stone formation Tubular ectasia (medullary sponge kidney) Horseshoe kidneyCaliceal diverticulum, caliceal cyst Pelvo-ureteral junction obstruction Ureteral strictureVesico-ureteral refluxUreterocele

What are the risk factors for recurrent stone formation?Medication associated with stone formation Calcium supplements (Normal adult - 20-50 mmol per day)Vitamin D supplements Ascorbic acid in megadoses (> 4 g/day) Triamterene Indinavir(acetazolamide)(Sulphonamides) Corticosteroid (increase enteric absorption of Ca)Chemotherapeutic agent (uric acid)

What are the Other risk factors for recurrent stone formation?Onset of urolithiasis early in life ( i.e. below 25 years of age)Stones containing brushite (calcium phosphate

Imaging

What is the diagnostic imaging of choice for renal colic?IVU has been the gold standard in the pastBowel preparation and 6-hour fasting KUB (preliminary film)Immediate nephrogram (1mg/kg Omnipaque) 5 mins > tomograms > 10 mins (compression and release in prone position) > 20 mins filmPost-micturition > delay filmLaterally visualized calyces on IVU not correspond to posterior row of calycesAbdominal compression during IVU is not necessary for child under 2The specificity and sensitivity of unenhanced helical CT was found to be similar or superior to that obtained with IVU

What are the advantages and disadvantages of IVU?AdvantagesRoad map for percutaneous procedure, clear calyceal / ureter anatomy, better function informationFor emergency on table IVU - use double strength contrast (2mg/kg)Less radiation(2.5mSv)Specificity 90%Disadvantagescontrast nephropathy, allergy to contrast (mortality 1/1 million)Can only see 90% stone (miss radiolucent stone)Time consumingLow sensitivity (60%)

What are the signs of obstruction on IVU?Cause delayed dense nephrogramClubbing of calycesDilated renal pelvis/ureterHold up of contrast

Normal IVU during pain cannot rule out ureteric obstruction as cause

What are the advantages and disadvantages of NCCT?AdvantagesNo contrast, demonstration of radiolucent uric acid & xanthine stoneShow alternative diagnosis, relationship with extra renal organ~100% sensitivity and specificityDisadvantagesHigher radiation (5mSv)Less clear calyceal anatomyLess suited for follow-up after the treatment of radiopaque stonesCannot see indinavir stoneGreenwell et al, British study

What are the signs of obstruction on CT?HydronephrosisIncreased renal sizePerinephric or periureteric strandingUreteric wall edema (rim sign)

How about KUB?NCCT should be the initial imaging examination for acute ureteric colicpreliminary KUB X-ray is unjustifiedAll stones visible on scout also seen on KUBReduce radiation and costKUB after +ve CT for Rx and F/U decisionsIf stone visible on scout no need for KUBIf NOT visible on Scout Perform KUB X-ray~ 1/3 will show a radio-dense stone

KUB still is required in the planning of treatment for urolithiasis.

What are the advantages and disadvantages of USG?AdvantagesNo radiation/contrast , cheap, accessible, radiolucent stoneShould be considered the first imaging test in children with suspected urolithiasis(In child, renal cortex appear bright on US)Sensitivity 80%, specificity 95%DisadvantagesNo road map, operator dependant, difficult or unable to visualize mid-distal ureter

What is the diagnostic imaging of choice for renal colic?KUB combined with US. Extensive experience shows that in a large proportion of patients these methods are sufficient for the diagnosis of a ureteral stoneSensitivity of KUB 50%, specificity 70%

What are the radiological feature of stones?

What are the important issues of IV contrast?Classified into ionic vs non ionic and low/ high or iso-osmolarHigh osmolar - more nephrotoxicThe most commonly used contrast media are the nonionic low osmolar which are still hypertonic with an osmolarity of about 600 mosmol/l eg omnipaqueThe only iso-osmolar contrast in clinical use is the visipaqueContrast media have a half life of 1 hour in the body and by 12 hours 90% is excreted by the kidneys

What are the precautions for those at risk of contrast allergy?Asthma (6X for low osmolar, 10X for high osmolar)Alternative IxDefer Ix if poor controlStandby emergency drugs boxAlways use low-molecular non-ionic contrast mediumGive a corticosteroid (e.g. prednisolone, 30 mg) between 12 hours and 2 hours before the contrast medium is injected

What is the risk of metformin of contrast injection?Metformin which was exclusively excreted by kidneyPrecipitate lactic acidosis ~1/10000 (serum lactic acid concentration > 5 mmol/L) in case of contrast-induced anuriaLactic acidosis is associated with high mortality, particularly when renal function is reduced Symptoms of lactic acidosis: Vomiting, somnolence, epigastric pain, anorexia, hyperpnoea, lethargy, diarrhoea and thirst Treatment: Diuresis 100 ml/h during 24 hoursSerum creatinine, lactic acid and blood pH should be monitored +/- ICU/medical care

What are the precautions of those taking metformin?EAU guidelineSerum creatinine level should be measured in every patient with diabetes being treated with metformin Metformin and normal serum creatinine metformin stopped for 48 hours from the time of the radiological examination until the serum creatinine remains normal Metformin & Reduced renal functionmetformin should be stopped 48 hours before administration of contrast medium metformin may resume 48 hours after the examination provided that serum creatinine remains at the pre-examination levelif contrast given to patient taking metforminmetformin stopped immediatelyhydration to ensure U/O 100ml/hr x 24 hoursmonitor serum Cr, lactic acid and blood gas

What is contrast nephrotoxicity? Increase of 25%, or at least 44 mol/L for Cr in 3 days following IV contrast administrationReduced renal perfusion and toxic effect on tubular cellsDirect nephrotoxic effectVasoconstriction of glomerular afferent arterioles causes a reduced GFR and increased renal vascular resistance

What are the risk factors of contrast nephropathy? Increased serum creatinineDehydrationAge over 70 yearsDiabetesCongestive heart failureNephrotoxic drugs, (NSAIDs, aminoglycosides)Multiple myeloma Injection of contrast medium at intervals less than 48 hours

When Contrast medium should not be given, or should be avoided?

How to treat anaphylactoid reaction (not mediated by antibody) after IVU?ABCIntubated if necessary100% O2 maskBP/P monitoringTwo large bore iv dripAdrenaline 0.5mg (1:1000 0.5ml) intramuscularly, repeat again every 5 minutes depending on pulse and blood pressurePiriton 10mgHydrocortisone 200mgICU care

What is the role of DMSA?99mTC dimercaptosuccinic acid Cortical imagingSplit renal function before planning definitive treatmentActively extracted by functioning renal tubules

How to prevent radiation hazards? Main slogan : ALARA as low as reasonably achievable( I ) Minimize scattering ( 1 ) Put the fluoroscopy beam under the table ( image intensifier is placed superiorly ) to minimize XR leakage and scattering.( 2 ) Keep the image receiver as close to the patient as possible :Decrease the distance between the focal spot and the receiverDecrease the fluoroscopic beam intensityDecrease blurring of the imageServe as a scatter barrier( II ) Decrease fluoroscopy exposure ( 1 ) Decrease fluoroscopy time( 2 ) Use of last image hold feature( 3 ) Collimation narrow the beam and limit the imaging area to the exact position of interest

How to prevent radiation hazards?( III ) Distance protection ( inverse square law )( IV ) ShieldingLead apron 0.5 mm thickThyroid shieldLead glove( V ) Dosage monitoring by wearing dorsimeter

Specific Stone type & underlying factors

Calcium Oxalate (85%)Hypercalciuria: 50%Definition: >7mmol Ca/day (men) , > 6mmol Ca/day (women) Absorptive: increase intestinal absorptionRenal: renal leakage of calciumResorptive: increase bone demineralization (hyper PTH)

Hypercalcaemia: Primary hyper PTH (1% form stone)

Hyperoxaluria: Absorptive (enteric hyperoxaluria): short bowel syndrome colon expose to more bile salts increase permeability of oxalateRenal: renal leakage of oxalatePrimary hyperoxaluria: increase hepatic oxalate production

Hypocitraturia: Citrate forms soluble complex with calcium , prevent binding to oxalateHyperuricosuria: High uric acid uric acid stone Ca oxalate form stone on its surface

Uric acid (5%)Human not able to convert uric acid to allantoin (very soluble)Thus urine is supersaturate with insoluble uric acidUric acid exits as 2 form in urine: Uric acid : insolubleSodium urate: 20x more soluble in alkaline pHHuman urine is acidic (metabolic product are acid) Thus low urine pH predispose to uric acid stone formation20% pt with gout have uric acid stone20% with uric acid stone have gout1% per year risk of stone formation after first gout attackMyeloproliferative disease: Txn with cytotoxic drug cell necrosis large amount of nucleic acid convert to uric acid plug in collective systemTxn: Alkalinization of urine

Ca phosphate (10%)Occur in patient with Renal tubular acidosis (RTA)Defect of renal H+ secretion urine alkaline + metabolic acidosisHigh urine pH increase supersaturation of Ca and PhosphateType 1 RTA (distal) :Failure of distal renal tubule to acidified urine70% type RTA form stoneUrine pH >5.5 , low citrate , hypercalciuriaBld: metabolic acidosis, hypo KIf urine pH > 5.5: use ammonium chloride loading test If urine pH remain > 5.5 incomplete distal RTATxn: acidified urine

Struvite stoneMagenesium , ammonium & phosphatesUrease-producing bacteria which convertUrea Ammonium + CO2Alkalinized urineTxn: acidified urineUrease producing bacteria: ProteusKlebsiellaSerratiaPseudomonasProvidenciaStaphylococcus, ureaplasma urealyticum

Cystine stoneAutosomal-recessiveDisorder of transmembrance cystine transportamino acids cystine, ornithine, lysine, and arginine, (COLA)Result in decrease absorption of cystine from intestine and proximal tubule of the kidneyAbout 3% of adult stone formers are cystinuric and 6% of stone-forming childrenCystine stones are relatively radiodense because they contain sulfur atomsCystinuria urine supersaturate with cystineCystine is poorly soluble in acid urineDx: Cyanide-nitroprusside colorimetric test (cystine spot test) if +ve 24 hour urine collection24hr cystine >250mg cystinuria Txn: alkalinization of urine

Xanthine stoneRareLike other purine stones they are radiolucent and can be confused for uric acid stonesXanthine oxidase deficiency is autosomal recessive Half of the homozygotes are asymptomatic Only biochemical evidence of lower serum uric acid levels and high urinary excretion of xanthineXanthine oxidase converts hypoxanthine to xanthine and then to uric acidAllopurinol inhibits xanthine oxidase and in high doses it can precipitate xanthine stones (eg treatment of Lesch Nyhan syndrome) Xanthine is less soluble than hypoxanthine and hence the latter does not tend to precipitate

Analysis of stone composition

What are the methods of analysis of stone composition?Polarizing microscopyX-ray crystallography Infrared spectroscopyAll patients should have at least one stone analysedRepeated analysis when any changes in urine composition, as a result of medical treatment, dietary habits, environment or diseases, might have influenced stone composition

Analyses in uncomplicated stone disease

What is diagnostic evaluation for single stone formers?History, P/EMedicationsFluid intakeBiochemical screenU&E, Ca,PO4, uric acid, bicarbonatePTH if Ca is elevatedUrineC/ST PH>7.5 Infected stonesPH

Biochemical InvestigationA bottle with HCL solution is used to measure calcium oxalate, phosphate, citrate and Mg A plain bottle is used to estimate uric acidTWO 24-hor urine collections for each set of analyses recommendCollecting bottles: 5% Thymol in isopropanol (10ml for a 2-L blt) orStored at < 8 degreeFasting morning spot urine sample should be analysed A spot urine sample can provide a rough guide to the need of further analyses

Analyses in complicated stone disease

Indications for metabolic stone evaluationRecurrent stone formersStrong family history of stonesIntestinal disease (chronic diarrhea)Pathologic skeletal #, osteoporosisHistory of UTI with calculiGoutSolitary kidneyAnatomical abnormalitiesRenal insufficiencyStones composed of cystine, uric acid or struvite

Evaluation of stone formers 1HistoryUnderlying predisposing conditionsMedications (Ca, Vit C, Vit D, steroids)Fluid intake, meat consumption

Evaluation of stone formers 2Blood screenSodium, potassium, Calcium, uric acidCreatinineParathyroid hormoneUrine analysispH (>7.5 infection,

What are the summary of analyses in patients with uncomplicated and complicated stone disease?Patients should be advised to discard the first void urine sample and start collecting urine from there on including the first voided urine sample of the following morning

Hypercalciuria: >200mg/dayAbsorptive: intestinal absorption decreased PTH normal serum calciumType I not responded to Ca restrictionType II responded to Ca restrictionRenal (also known as renal leak)- High urinary Ca increased PTH normal serum calciumResorptive: hyperPTH: excessive PTH excessive bone resorption increase renal synthesis of Vit D increase intestinal absorption of Ca hypercalcemiaMalignancy associated hypercalcemiaGlucortocoid induced hypercalciuria

Hyperoxaluria (urinary oxalate > 40mg/day)Increased urinary saturation Calcium oxalate CausesPrimary (deficiency liver enzyme > early renal failure > renal and liver transplant)Enteric (chronic diarrhoea with fat malabsoption increase oxalate reabsorption, eg Bowel resection, IBD )Dietary: chocolate, spinach, nuts, strawberry, tea and ascorbic acid

Hypocitraturia ( 2.5mg/dl

Low Urine pH (

Hyperuricosuria (urinary uric acid >600mg/day)Uric acid reduces effectiveness of urinary inhibitors of crystallization promote Ca oxalate formation Increased dietary purine intake, gout, myeloproliferative and lymphoproliferative disorder, multiple myeloma, hemolytic disorders and increased insulin (decreased urine pH)

Uric acid stone3 main determinants Low pHLow urine volumeHyperuricosuria

Uric acid stone Low urine pHMost important factor (most patients have normal uric acid level but invariably have low urine pH)at pH 5, even modest amount of uric acid exceed solubilityLow pH increases concentration of sparingly soluble undissociated uric acid direct precipitation of uric acid

What is cystinuria?Autosomal recessive Type A (chromosome 2), Type B (chromosome 19) type AB Associated with defective renal absorption of cystine, ornithine, lysine , arginine (COLA), only cystine insoluble1% of all renal stones The incidence of homozygous cystinuria is 1/20,000 and heterozygous 1/20 to 1/200Median age of 20-30The 24 hour urine excretion of normal cystine is 600 mg/day, heterozygotes > 400mg/day Cystine stones commonly form in homozygous cystinurics but heterozygous cystinurics can form renal stones which may well not be cystine stonesCystione stones >4mm will normally be radioopaque due to their disulphide bonds Ground-glass appearance and hexagonal crystal in microscopy

What is Brands test?Qualitative test for detecting cystine in urine >75mg/lSpot test for cystinuria 12 drops of Na cyanide are added to the urine sample to stain the urine pinklyCyanide converts cystine to cysteine which binds nitroprusside causing purpleFalse positive results may occur in homocystinuria or acetonurina, sulpha drugs, ampicillin or N-acetylcysteine

What is the treatment for cystine stone?Diet: low in methionine, Na < 2g/dayDrinking: 24 hour urine > 3LDrug: Potassium Citrate: 20-25 mmol/day TDSComplex formation by chelating agents: Thiol compounds: Vit B6 50mg QD togetherD-penicillamine (1-2g/day)Alfa- mercaptopropionyl glycine (tiopronin) 750mg/day)Captopril : 75-100mg QDAccompanied by pyridoxine to avoid vitamin B6 deficiencyRegular urine protein to detect nephrotic syndrome caused by penicillamine or mercaptopropionyl glycine

What is the medical treatment for cystine stone?

Renal tubular acidosis

Child presents with stunted growthWhat is the diagnosis? (1)What is the physiological abnormality in this child? (1)Name the metabolic abnormality (1)What is the usual urine pH? (1)What is the usual component of stone formation? (1)Q59

KUB : bilateral medullary nephrocalcinosisDx : RTA type 1 (1)Inability to excrete acid from collecting duct despite metabolic acidosis (1)Hypokalemic, hyperchloremic, nonanion gap metabolic acidosis (1)Elevated urine pH (>6.0), hypercalciuria, hypocitraturia (1)Calcium phosphate (1)

Renal Tubular AcidosisSyndromes of metabolic acidosis resulting from defects in tubular hydrogen secretion and urinary acidificationRTA I The most common form of RTAThee majority of patients are females (80%) and 70% of them will form stonesFailure of H+ secretion in the distal nephronMetabolic acidosis promotes bone demineralisation : secondary hyperparathyroidism, hypercalciuria hypocitraturia, coupled with high urine pH => calcium phosphate stonesUsually occurs in adults : typical bilateral medullary nephrolithiasisChildren : vomiting, failure to thrive, growth retardationPrimary : idiopathic, hereditary (autosomal dominant or autosomal recessive), sporadicSecondary : autoimmune diseaese, Sjogrens syndrome, SLETx: Sodium bicarbonatePotassium citrate

RTA II - Due to Failure of bicarbonate reabsorption in the proximal tubuleAssociated with generalised defect in proximal tubule function eg. reabsorption of phosphate, urateAssociated with other absorptive deficiencies (Fanconis syndrome)Do not tend to form stones due to increase urinary citrate. Metabolic acidosis leads to growth retardation and hypokalemia RTA IV Impairment of cation exchange in the distal tubule, reduced secretion of H+ and K+. The unique feature is hyperkalemiaAssociated with underlying aldosterone deficiency or resistanceClinically associated with chronic renal damage such as diabetic nephropathy / interstitial renal diseaseRenal stone formation uncommon as excreted substrates eg. Ca and urate decreased due to impaired GFR

What are some parameters to raise suspicious of renal tubular acidosis ? Hypokalaemia hyperchloremic metabolic acidosis, increased urine K and Na, hypocitraturia, hypercalciuria from resorption of bone, hyperphosphaturiaCalcium phosphate stoneIf pH above 5.8 in fasting morning urine = complete RTAIf urine pH is >5.8, confirmed by the ammonium chloride loading test (oral 0.1g/kg = acid load). Urine pH that remains above 5.8 after an oral dose of ammonium chloride = incomplete RTA

(What are the analytical findings in patients with complete or incomplete distal renal tubular acidosis?)

ESWL

4 factors of ESWLEnergy sourceCouplingSystem to transmit shockwave to decrease energy lossFocusingAcoustic lensCylindrical reflector ImagingUSG, fluoroscopy or both

Generator typeElectrohydraulic lithotripsy (EHL)Spark is produced between two electrodes under water, which results in the rapid expansion and collapse of a gas bubble and subsequent energy transmissionA metal hemi-ellipsoid reflector is used to focus the energyResult in great shot-to-shot variability as electrode wear downElectromagnetic lithotripsyCylindrical electromagnetic source, and energy is focused by an acoustic lensPiezoelectric lithotripsyPiezoelectric materials consist of ceramic or crystal elements (barium titanate) that produce an electrical discharge under stress or tension, or can be induced to rapidly expand by the application of a high-voltage pulse. The piezoelectric elements are placed on the inside of a spherical dish to permit convergence of the shock frontFor EM & PE acoustic output instability may occur

1. Electrohydraulic2. Electromagnetic3. Piezoelectric

Shock waveWhat is shock wave?A short-duration (

Newer generatorHigher peak pressure (more effective?)Small focal zones (less painful)Ideal for txn of ureteral stoneNo observe improvement in SFR

F1: electrode (focus of an ellipsoid)F2: target (kidney stone)

Dual HeadsSW generated simultaneously from 2 reflectors through 2 axes in non-opposinig directions to the same F2Intensifies and localizes cavitational effectsBetter quality and rate of stone disintegration

Electroconductive4th generationElectrode surround by highly conductive solutionShock generation by discharge between anode and cathodeRepeatable spark location due to shorter interelectrode distance and reduced electrode wear (vs EHL)Electrode life time > 40000 impulsesspark generation exactly at F2

ElectroconductiveEfficacy of the lithotripter Latest-generation lithotripters are at least as effective as the first lithotripters, but are much cheaper and have greater versatility 4th generation: SonolithElectroconductiveLarge focal diameter of the SW (12.825 mm)A longer pulse duration (138279 ns)A relatively lower peak pressureAchieved a high success rate, comparable with that using the HM-3 machine but with lower analgesia requirements and very low re-treatment rates

ECL vs EHLReduction in shockwave pressure variabilityImproved energy transfer to the stoneLinear relation between the voltage setting and the pressure at F2 stone FragmentationResult TolleySonolith between 2004 and 2006plain KUB and USG at 1 and 3 monthsSFR: 77% (20mm)74% (lower), 70% (upper), 78.5 (middle), 74% (renal pelvis)

Mechanism of stone comminutionStone communition is a progressive process consisting: Initial (base of dynamic squeezing) propagationAnd colaescence (because of increasing fragility) Mechanical stress produce micro-cracks sudden break off of the calculus

Spallation ()Once the shockwave enters the stone, it will be reflected at sites of impedance mismatch. One such location is at the distal surface of the stone at the stone-fluid (urine) interfaceAs the shockwave is reflected, it is inverted in phase to a tensile (negative) wave. If the tensile wave exceeds the tensile strength of the stone, there is an induction of nucleation and growth of microcracks that eventually coalesce, resulting in stone fragmentationCavitation ()During the negative pressure wave, the pressure inside the bubble falls below the vapor pressure of the fluid, and the bubble fills with vapor and grows rapidly in size (almost three orders of magnitude). As these bubbles grow, they oscillate in size for about 200 s and then collapse violently, giving rise to high pressures and temperatures. In the absence of any boundaries, a cavitation bubble remains spherical during collapse, releasing energy primarily by sound radiation, the majority of which is in the form of a shockwave

Circumferential compression ()The shockwave inside the stone advances faster through the stone than the shockwave propagating in the fluid outside of the stone. The shockwave that propagates in the fluid outside of the stone thus produces a circumferential force on the stone

Tear & Shearing ()In contrast to compression waves, which move the molecules in the direction of propagation, a shear wave results in translation of molecules transverse to the direction of propagation, and therefore the molecules are not compressed but are shifted sideways by the wave

Dynamic squeezing: ()Stone fragment by shear waves created inside the stone driven by squeezing wave from the lateral stone bordersA model accounts for all acoustic phenomenon

What are the imaging systems during ESWL?FluorosocopyAdvantagesIn-situ tx of ureteric stonesin all parts of ureterShorter learning curveDisadvantagesNo direct targeting of radiolucent stonesSmall stones sometimes are difficult to locateExposure to radiationUSG AdvantagesEasy targeting of radiolucent stones and smaller renal stonesReal-time imaging without excessive radiation exposureDisadvantagesIs-situ treatment of ureteric stones is possibly only for prox and distal ureterLonger learning curve

Factor influence efficacy1. Focal zone: Diameter at which the peak pressure is half of P+, known as -6dBEnergy focused on stone depends on source and method of focusingBut focal zone has little relevance in the disintegrative efficacyUsually: larger FZ renal stone, small FZ ureteric stoneIn short : larger FZ increase efficiency

2. Pulse rate frequency: Cavitation bubbles produced by the rarefaction phase of the SW can decrease the energy of the following impulse thru scattering and absorptionLonger pulse frequency less bubble in the path to decrease the energyOnly the ve phase is affectedIncrease PRF from 1Hz to 1.8Hz has drastic effect on SW energy

3. CouplingHM3 use water bath now coupling cushionsMore air pockets less SW efficacyGel: use bubble-free USG gelLower viscosity gel betterGreater quantity of gelApply gel from stock container as a large amount rather than hand or zigzag application from squeezed bottles

4. Localization & monitoring:Compression belt to reduce resp movementLarger FZ to reduce impulse miss the stoneReal time coaxial USG localization Automated fluoroscopic localization5. Impact on pulse rate: Reduce pulse from 2Hz to 1Hz increase stone passage rate from 20% 80%RCT: 1Hz has better outcome vs 2Hz esp with stone > 10mm (60% vs30%),

6. Ramping: Slow increase of generator voltage Less painPretreatment at lower voltage reduce renal trauma by vasoconstriction7. SW energy: Stone fragmentation is achieved as long as the threshold is exceedBase of effective energy dose (Eeff at intensity level x impulses) Renal stone: Edose (12mm)= 100-130Ureteral stone: Edose (12mm) = 150-200

Contraindications AbsolutePregnancy Uncorrected bleeding disorder Uncorrected hypertensionUntreated infectionBody habitus (obesity or severe skeletal malformations) RelativeAneurysmPacemakerDownstream obstruction (e.g PUJ stone)Excessive stone burden

What is the important point for Steinstrasse? Internal ureteral stents are now commonly inserted before ESWL for large renal stones, the frequency of Steinstrasse has decreased Steinstrasse: Accumulation of gravel that does not pass within a reasonable period of time , and interferes with the passage of urinePCN results in passage of fragmentsURS: help remove the leading stone in distal ureter

Factors predicting usefulnessStone free rate (EAU 2010)2cm 50%Stone factorsSizeSiteComposition as measure by HU on CT scan (> 1000)Calyceal anatomyPatient factorsAge: for renal stone, age stone free rateBMIStone skin distancePain control

sizeEAU 2010>20mm consider PCNL although ESWL still an option> 40 x 30mm combine PCNL and ESWL 71%-96% success (sandwich procedure)But single kidney can still try ESWLESWL after PCNL better then vice versa*

Stone BurdenCan be expressed in different wayLargest diameter: length of stone on KUBStone surface area (SA): Length, width

Stone volume (SV): CT

CompositionStone resistant to ESWL in descending order :CystineBushiteCa oxalate monohydrateHydroxyapatiteStruviteCa oxalate dihydrateUric acidMatrix stone, soft stone composed of up to 65% organic matter, compared to 3 4 % of most noninfected stones, is associated with poor outcome with ESWL, and PCNL is preferred

Hard stoneHard stone like cystine and brushite should be treated with ESWL only when they are < 15 mm in size. RIRS may be beneficial in cystine stone, because life-time risk of recurrence, therefore less renal trauma and less morbidity.EAU 2010 : cystine stone< 15mm ESWL 71% SFR> 20mm ESWL 40% SFR

What is the importance of shape & CT HU unit to determining successful rate of ESWL to cystine stone?Rough-appearing external surface on plain film imaging were more apt to be fragmented with shock-wave energy than those with a smooth contour Computed tomography attenuation coefficients of the latter were significantly higher in smooth-type stones HU > 1000 asso with reduce stone disintegration 50% vs 100% if HU < 500 [Joseph JU2002]Stones with higher attenuation values have also been demonstrated to be resistant to shock-wave fragmentation

When is stenting required in ESWL?Indication: Obstructed infected systemNew-onset of renal failureStone > 2cm : steinestrasse after ESWL 10% (vs 1% if < 2cm)Improve passage of stonePrevent obstructionPrevent loss of ureteral contraction

Stent with ESWL useful?Stent + ESWL for proximal ureteral stone does not affect stone fragmentation or clearance, but associated with more symptom (Grade 1B)Recommendation against stenting for proximal ureteric stoneRoutine Ureteric stents compromise stone clearance after shockwave lithotripsy for ureteric stone [Tolly BJUI 2008]

Prophylactic antibiotic

Antibiotic prophylaxis in pt with sterile urine before txn reduce risk of UTI (2% vs 6% in placebo) [MA ,Pearle Ju1997]Expert panel from AUA [JU2003]Not indicated for most of the urology patientsNot indicated for pin, plate or screwAdvised for patient who had increased risk of hematogenous joint infection (Total joint replacement)For total joint replacement within 2 yearsImmunocomprimised patientCo-morbidityPrevious joint infectionMalnourishedHIV infection, DM, malignancy

PainRelated to energy density of SW as it passes through skin, size of focal pointshort acting parenteral sedative narcotics: alfentanil, midazolam, propofoltopical agents: EMLA cream (mixture of lidocaine and prilocaine) 45 mins before SWLPain control is important to reduce patient movement causing mistargetingPrefer: Oral + IV PRN (Alfentanil) [Ng 2009]those who receive GA experienced a significantly greater stone free rate than IV sedation( Due to more controlled respiratory excursion)

Evidence of pre-treatment SWWillis (2006) reported a practical way to protect the treated kidney from clinical dose of shockwaves. Before the administration of a clinical dose of 2000 shocks at 24 kV with an unmodified HM3 lithotripterA pretreatment dose of 100 to 500 shockwaves at 12 kV is administered, followed by the full clinical dose to the same site.Under these conditions, the normal lesion of approximately 6% is reduced to approximately 0.3%, a highly significant change One hypothesis of a possible mechanism of this outcome Pre-dose of shockwaves induces vasoconstrictive event that prevents an incoming stress from shearing the vessel wall Or prevents or reduces the number of cavitation events.A reduction in cavitation potentially protects the parenchyma from cavitation-induced injury. A clinical trial is needed to test this result in patients Occur when the treatment is apply to same or opposite pole (give 100 shock for pretreatment)

ESWL best practice (EAU)Best Txn of patient who desire txn with minimal anaesthesiaRenal stone 1cmUreteral stent should be inserted in case renal stone >2cmHowever , stenting should not be use for proximal ureteric stone dose not affect stone fragmentation or clearance but asso with more symptomsStones with medium density >1000HU upon NCCT are less likely to be disintegratedObesity poor localisation with imaging and increase skin to stone distance poor outcomeWomen of childbearing age: caution in txn of distal ureteric stone with ESWL possibility of damage to undertilised egg or ovariesNO asso of SWL with HT and DM

Mid-ureteric stone proneLower ureteric stone -Traditionally proneOptimal frequency is 1Hz (safer and more effective, start with low energy and stepwise power ramping)Shock-wave frequency increases, tissue damage increases Meta-analysis comparing 60 shocks/min vs 120 shocks/minPatient treated with 60 shocks/min, significant greater likelihood of a successful treatmentEscalating voltage may have protective effect against ESWL damage and better stone clearance

ESWL should be performed by urologist who was experience in ESWLThe number of ESWL sessions : not exceed three to fiveFor more sessions, a percutaneous method No rules on how frequently ESWL sessions can be repeated Two successive sessions must be longer for electrohydraulic and electromagnetic lithotripsy than for treatments using piezoelectric equipment Careful and long fluoroscopy and USG time is essentialDecrease air pocket in coupling gel is essential apply USG gel to water cushion straight from container rather than by handCareful control of pain during treatment is necessary to limit pain-induced movements and excessive respiratory excursions

MET after SWLMeta-analysis BJUI 2009 Yefang Zhu : Tamsulosin Improves clearance of fragments after ESWL by 20%With ~1 week faster stone passageReduce pain medication requirementFewer returns to hospitalSteinstrass resolve completely vs 25% require intervention in placebo gpWork best esp in stone > 10 to 24mmK citrate for Ca Oxalate stone: Improve SFRMET vs ESWL: Equally effective in distal ureteric stone 4-7.9mmMET less effective in stone 8-9.9mm

ConclusionMET is recommended (both nifedipine and tamsulosin) in facilitating clearance of fragments after ESWL of ureteral stone and to reduce pain medication requirement

Complications after ESWL?PainHematuriaUTI and occasional sepsisSteinstrasse complicates (1-4%) 10% if > 2cmPerirenal hematoma (25% radiological) (

Who are at risk of complication?Acute renal injury may be more likely to occur in patients Pre-existing hypertensionProlonged coagulation timeCoexisting coronary heart diseaseDiabetes Solitary kidneys

URSL

IndicationsStone factor: ESWL failure Lower pole stoneCystine stonesBilateral ureteric stoneStone in a calyceal diverticulum Stenosis of a calyceal infundibulum or tight angle between renal pelvis and infundibulum. The flexible ureteroscope can negotiate acute angles and the laser can be used to divide obstructions.

Patient factors: Obesity such that PCNL access is technically difficult or impossible Obesity such that ESWL is technically difficult or impossible. BMI >28 Musculoskeletal deformities such that stone access by PCNL or ESWL -e.g.kyphoscoliosis)Bleeding diathesis Horseshoe or pelvic kidneyESWL only 50% successPCNL difficult : bowel proximity and variable blood supplyPatient preference

Advantage of URSLAccess to virtually the entire collecting system is possibleHolmium:YAG laser has a minimal effect on tissues at distances of 23 mm from the laser tip and so collateral tissue damage is minimal More effective treatment option than ESWL, with a lower morbidity than PCNLlaser lithotripsy (reliable method for treating urinary calculi, regardless of hardness)It can also allow access to areas of the kidney where ESWL is less efficient or where PCNL cannot reachSafely used in pregnancyTreatment of bilateral ureteral stone simultaneouslySmall stones and fragments are best retrieved with a basket or a forceps most suited to stones

Standard technique

Ho: YAG laser lithotripsyRegardless of hardnessUreteral stones: 365-um laser fibreIntracaliceal stone: 200-um fibreBetter SFR at 3 months than EHL (97% vs 87%)

What are the advantages of access sheath?Ureteral access shealth: 9-16FOperating time might be reduced for higher stone burdens where multiple ureter passages are necessary The maintenance of a low-pressure irrigation system by continuous outflow through the sheath follow-up series indicate a low rate of ureteric strictures

What is the advancement of baskets?Nitinol baskets preserve tip deflection of flexible ureterorenoscopes Tipless design reduces the risk of mucosa injury Nitinol baskets are most suitable for use in flexible URSNitinol baskets are more vulnerable than a stainless steel basket, and laser or EHL might break the wires of the basket

SFROverall SFR: 81-94% Appropriate for stone of any size in proximal ureter: SFR 81%Proximal stone: Flexible URS (87%) vs Semirigid URS (77%)< 2cm: >80%> 2cm: 50%Majority of pt stone free in single procedure, 10% require auxillary procedure

EAU GL 2010

RIRS result on Renal stoneSFR for stone < 15mm : 50-80%Larger stone can also be treated successfullyNOT recommended as 1st line for renal stoneFlexible URS could become 1st line for lower pole stones < 15mm Simultaneous URS + PCNL: not routine

Stone extractionIntraureteral manipulations with stone basket should always be performed under direct URS visionFluoroscopic imaging of the stone alone is not sufficientObvious risk of injury to ureter

Consent: Intraoperative complicationBleeding (0.1%)Ureteral injury (0.5%)Ureteral avulsions (0.1%)Stone migration (4%)

Early complication: Fever or sepsis (1%)Hematuria (2%)Renal colic (2%)Transient VUR (4%)Late complication: Ureteric stricture (0.5%)

StentingNo improved fragmentation with stentingFrequent LUTS related to stentsRoutine stenting after uncomplicated URS not necessaryComplications: stent migration, UTI , breakage , encrustation and obstructionIncrease expense, FC for removalStrong recommendation against routine stenting after uncomplicated URS (Grade 1B)Clear indications: Ureteral injury or perforationLarger residual stone burden Stone fragments >2mm remain in ureterImpacted stone with edematous ureterProlonged manipulation (esp upper 1/3)StrictureSolitary kidneyRenal insufficiency

PCNL

IndicationsFor stone 3 cm in diameter Failed ESWL and/or an attempt at flexible URSL Staghorn calculiESWL and/or repeat PCNL being used for residual stone fragments. For stones 23 cm in diameter, PCNL gives the best chance of complete stone clearance with a single procedure, but this is achieved at a higher risk of morbidity.

Prophylatic antibiotic?Mariappan and associates (2005) have reported thatthe best predictor of post-PNL urosepsis is stone culture or renal pelvic urine culture results, rather than bladder urine culture results. The fragmentation of stones, despite sterile urine, may release preformed bacterial endotoxins and viable bacteria that place the patient at risk for septic complicationsTherefore, struvite stone pt or in whom infection is suspected should receiveminimum of 2 weeks of broad-spectrum antibiotics before surgery to reduce the risk of sepsis.Parenteral antibiotics should be administered preoperatively in any patient in whom urinary infection is suspected.

Patients with radiological evidence of struvite stone should be treated with oral antibiotic x 2 weeks even with sterile urine ( 35 % incidence of bacteruria after PCNL )Prophylactic antibiotic should be given to all cases ( reduce the incidence of post-op UTI from 12 % to 2 % , Tolly )Cephalosporin is the most suitable prophylactic antibiotic given in case of sterile urine because the most common secondarily infecting organism is Sta. Epidermidis

ProcedurePre-procedural USG + fluoroscopy:Best access site and stone positionEnsure no organ within the planned pathPCNL is the removal of a kidney stone via a track developed between the surface of the skin and the collecting system of the kidneyGeneral anesthesia is usual, though regional or even local anesthesia (with sedation) can be used Inflation of the renal collecting system (pelvis and calyces) with fluid or air instilled via a ureteric catheter inserted cystoscopically A posterior approach is most commonly usedbelow the 12th rib (to avoid the pleura and far enough away from the rib to avoid the intercostals, vessels, and nerve)through a posterior calyx, rather than into the renal pelvis, because this avoids damage to posterior branches of the renal artery that are closely associated with the renal pelvis.Percutaneous puncture of a renal calyx with a nephrostomy needleOnce the nephrostomy needle is in the calyx, a guide wire is inserted into the renal pelvis to act as a guide over which the track is dilated An access sheath is passed down the track and into the calyxThrough this a nephroscope can be advanced into the kidney An ultrasonic lithotripsy probe is used to fragment the stone and remove the debris.

Calyceal AnatomyLAMP lateral ant, medial postBrodel configuration:posterior longer, more lateral (many l)69% Rt kidney is BrodelHodson configuration :posterior shorter, more medial (s, no l)79% Lt kidney is Hodson99% superior calyceal group drain by 1 midline infundibulum96% midzone drained by paired calyces arranged in 2 rows (anterior and posterior)

Puncture: Munver

ResultFor small stones, SFR 9095%For staghorn stones, SFR of PCNL + postoperative ESWL for residual stone fragments : 8085%

Result: upper pole punctureTolley, Western General Hospital [BJUi 2007]66 PCNL with upper pole punctureOverall SFR : 78%Thoracic complication: 3%Overall complication: 30%Conclusion: Upper pole puncture asso with minimal morbiditySFR depends on size of stone rather than puncture site

What are some tricks of PCNL?The puncture site on the skin lies in the extension of the long axis of the target calixThe puncture avoids aiming at infundibulumThis is the safest access point because it uses the infundibulum as a conduit to the pelvisPuncture pass thru papilla (no major blood vessels)Staghorn stone: subcostal or supracostal upper pole punctureCT-guided renal access may be an option if failed fluoroscopic or US guidedRenal tract dilatation is possible using the Amplatz system, or balloon dilators (no difference in morbidity, less operation time but more cost)Lower pole puncture at posterior calyx - Mid-pole stone will be left

Percutaneous antegrade accessIndications: Cases with large impacted upper ureteric stone (>15mm)Combination with renal stone removalUreteral stones after urinary diversionFailure of retrograde ureteral access to large, impacted upper ureteral stonesSFR: 85% and 100%Complication rate: low and acceptable

What is mini-perc?Smaller shaft calibres of 12-20 F Mini PCNLVS PCNL (prospective study by Li Ly)Operation time was longerBlood transfusion rates lowerNo significant differences in trauma responseAs treatment time increases with stone size, this method is recommended only for stones with a diameter < 20 mmThe value of mini-perc in adults has not been determined, but mini-perc is the method of choice for percutaneous stone removal in children

What are the pros and cons of supine PCNL?RCT showed no difference between supine and prone PCNL except less operation time in supine

Films taken after an urologic operationWhat has happened? (2)What is the incidence? (1)Q23

Colonic injury during PCNL

Tubless PCNLExclusion criteria included :operative time longer than 2 h, three or more percutaneous accesses, perforation of the collecting system, bleeding, significant residual stone burden. Obstructed ureterAll patients had antegrade stents placed after PNL ( 6F stents for stone patients and 14/7F stents for endopyelotomy patients. )Adv :shorter hospitalizations (1.25 days) lack of external drainage tubes. Disadv :wearing a urinary catheter for 24 h, a second procedure is necessary for stent removal.

What are indication and contraindication of PCNL?Indication: Stone > 3cm or staghorn stoneRenal pelvis stone > 2cmLower pole stone > 1cmAnatomical abnormaly : horseshoe kidney, calcyceal diverticular stone , obesity, kyphoscoliosisFailed ESWL or URSLForeign body

Contraindication: Absolute : Bleeding disorderProegnancySpesisPoor kidney fxn (nephrectomy) Need of open procedureRelative: Horseshoe or ectopic kidney (bowel injury)Co-morbiditiesAnterior calyceal divedrticulum

What are the complication of PCNL?Access: Bleeding (10%)Require embolization (1%)Require nephrectomy (rare) Perforation of adj organ (bowel

Major bleeding: Termination of operationPlacement of nephrostomy tubeSecondary intervention at later dateClamp nephrostomy tube to stop venous bleedPersistent or late secondary bleedingArtery injuryAngiographic super-selective embolisationNephrectomy is rare

Open/Lap renal stone surgery

IndicationsComplex stone burden (projection of stone into multiple calyces, such that multiple PCNL tracks would be required to gain access)Failure of endoscopic treatment Anatomic abnormality that precludes endoscopic surgery (e.g., retrorenal colon)Body habitus that precludes endoscopic surgery (e.g., gross obesity, kyphoscoliosis)Patient request for a single procedure where multiple PCNLs might be required for stone clearanceNonfunctioning kidney (pain, recurrent urinary infection, hematuria) esp with staghorn stone to reduce infective complication

OptionsSmall to medium-sized stonesPyelolithotomy Radial nephrolithotomy Staghorn calculiAnatrophic (avascular) nephrolithotomy - Extended pyelolithotomy with radial nephrotomies (small incisions over individual stones)Excision of the kidney, bench surgery to remove the stones, and autotransplantation

ComplicationsWound infection (infection stones)Flank herniaWound painStone recurrence after open stone surgery Scar tissue that develops around the kidney will make subsequent open stone surgery technically more difficult.The superiority of open surgery over less invasive therapy, in terms of stone-free rates, is based on historical experience, but no comparative studies are available yet

Lap ureterolithotomyRetroperitoneal or transperitoneal accessWhen other non-invasive procedure failedFor both renal and ureteric stoneEsp for stone in ventral caliceal diverticulum< 2% conversion rate

Medical dissolution therapy

IndicationUric acid stone:Uric acid stones form in concentrated, acid urine to decrease acidity of urineHydration (urine output 23 L/day)Urine alkalinizationAim urine pH 6.57 sodium bicarbonate 650 mg TDS or potassium citrate 3060 mEq/dayAllopurinol:For those with uric acid secretion > 1200mg/dayInhibits conversion of hypoxanthine and xanthine to uric acid300600 mg/dayDietary manipulation (low purine diet)

Cystine stonesMost cystinuric patients excrete about 1 g of cystine per dayCystine solubility in acid solutions is low (300 mg/L at pH 5, 400 mg/L at pH 7)Treatment: Reduce cystine excretion (dietary restriction of the cystine precursor amino acid methionine and also of sodium intake to pH 7.5, maintenance of a high fluid intakeDrugs that convert cystine to more soluble compoundD-penicillamine, N-acetyl-D-penicillamine, & mercaptopropionylglycine Bind to cystin the compounds so formed are more solubleD-penicillamine (allergic reactions, nephrotic syndrome, pancytopenia, proteinuria, epidermolysis, thrombocytosis, hypogeusia)Cystine stone are very hardFlexible ureteroscopy (for small) and PCNL (for larger) cystine stones are used where ESWL fragmentation has failed

Chemolytic dissolutionAdjunct to ESWL, PCNL, URS, open Sx to achieve more complete elimination of small residual stone/fragmentsStaghorn stone: ESWL + dissolution as low invasive option2 nephrostomy catheters to irrigate renal collecting systemPrevent chemolytic fluid draining into bladderReduce risk of increased intrarenal pressureLarge stone burdenJJ stent to protect ureter

Percutaneous chemolysisInfection stone10% solution of Hemiacidrin (Renacidin), pH 3.5-4, orSubys G solutionAbx prophylaxisOne PCN in, another PCN outIncrease contact surface area with ESWLSeveral week chemolysis + ESWL x complete staghornOption of High risk ptRisk: cardiac arrest due to hypermagnesaemiaContraindicated in immediate postop stage

Percutaneous chemolysisBrushite stone:Hemiacidrin/ Subys G solution, for residual fragments after other TxCystine stoneSoluble in alkaline 0.3-0.6mol/L THAM (trihydroxymethyl aminomethan) solution (pH 8.5-9), or 200mg/L N-acetylcysteineUric acid stoneTHAMDissolve with bicarbonate treatmentCa Oxalate or ammonium urate stoneNo useful RxCa Oxalate in infection stone markedly reduce stone solubility in Hemiacidin

Treatment

Natural history of renal stone15% pass & 50% require intevention in 5yr [Glowacki 1992]Asymptomatic calyceal stone < 15mm: no difference SFR, QOL, RFT & admission [MRC, Keeley BJU2001]EAU 2010: Spontaneous stone passage rateRenal stone< 4mm : Spontaneous pass 80%6-10mm : pass 10-53%Stones > 5 mm - highly likely obstruction, drop in relative renal function and require intervention

Ureteric stoneProximal 25%, mid 45%, distal 70%

WW ? For whoTraditional indications for intervention are pain, infection, and obstructionAsymptomatic stones followed over a 3-year period are more likely to require intervention (surgery or ESWL) or to increase in size or cause pain if they are >4 mm in diameter and if they are located in a middle or lower pole calyxPatients job

What are the indications for active stone removal? EAU

Renal stone: recommendationsMethod offering lower invasiveness or morbidity should be selected< 10mm ESWL10-20mm ESWL as first line but PCNL is 1st line for LPS> 20mm PCNL is preferredUric acid stone: oral chemolysis +/- disintegration

Staghorn stone

Staghorn stoneWhat is staghorn stone?Definition: Stone with a central body and at least one caliceal branchPartial staghorn: fills only part of collecting systemComplete staghorn: fills all calices and renal pelvisWhat is it compose of ?Struvite stone (calcium, ammonium and magnsium phosphate) Urea spliting organsim (PKS PPS) Urea ammonia (NH3) + bicarbonateAmmonia(NH3) + H2O ammonium NH4 + OH

Staghorn stoneWhy need to treat staghorn stone?According to study by Blandy and Singh [JU1976]Staghorn stone cause symptomIf left with observation : 28% die of stone related renal failureIf treat with surgery: mortality is only 7%According to study by Teichman [JU1995]NO patient with complete stone clearance die of renal related disease vs 3% without clearance of fragments and 70% who refuse surgery~30% of patients with staghorn calculi who did not undergo surgical removal died of renal-related causesrenal failure and urosepsisThus treatment of staghorn stone is indicate

How should staghorn stone be treated?For stone> 2cmESWL: No because SFR 40-60% at mostFlexible URS: no because SFR < 60%PCNL : yes because highest SFR : >90%Open surgery vs PCNL in complete staghorn stone [Egypt Gp (Al-Kohlany, JU2005]Conclusion:PCNL approaching the SF of openAt discharge (49% vs 66%) and at FU (74% vs 82%)PCNL : lower morbidity, shorter operative time, shorter hospital stay and earlier return to workStone-free rates for both groups at follow-up were approximately 80%

AUA GL stone free rateMEDLINE search 1992 7/2003

Combine SFR lower because the last procedure is SWL in some series

SFRSignificant complicationTransfusionProcedure per patientPCNL78%15%18%1.9PCNL + SWL66%14%17%3.3SWL54%19%Very low3.6Open surgery71%13%~20-25%1.4

Bilateral staghorn stoneManage symptomatic first, then good function side in bilateral staghorn disease Determined by DMSA, best for the differential functionSimultaneous bilateral PCNL is safe with advantage of single anesthesia except large stone burden and complex pelvicalyceal system

Lower pole stone

Natural hx of LPSFrom 4 reportsApproximate 10-20% asymptomatic stones become symptomatic per yearFor these, 50-60% eventually require surgical intervention

Lotan et al J Urol 2004 172 (6) p2275-81

Any benefit of treating it?MRC trail [F.X Keeley el at. BJUi 2001, 87, 1-8]

Preliminary results of a randomiszed controlled trial of prophylactic SWL for small asymptomatic renal calyceal stones228 patients randomised to ESWL vs control All 70% LPSESWL Max 3 sessionFU 2.2: SFR: ESWL 28% vs observe 17% (insignificant)addition tx ( include analgesic/ antibiotic / JJ / URS ): ESWL 15% vs observe 21% Thus: ESWL will have an increase SFR & less additional txn require

Is ESWL less effective in LPS?Overall SFR of LPS vs upper & mid PS 60% vs 90%Meta-analysis by Lingeman [JU1994]Stone size stratification Up to 10mm: 75%11-20mm: 55%Over 20mm: 30%

What determine the SFR of LPS?Lower pole collective system anatomy [Sampaio JU1992]Angle btw lower LP infundibulum & renal pelvisDiameter of the LP infundibulumSpatial distribution of the calycesBut they are controversial

How do they affect?Lower pole infundibulopelvic (LIP) angle as define as: Angle btw lower border of the pelvis with medial border of the LP infundibulum [Keely EU1999]Angle btw central pt of renal pelvis & central axis of LP infundibulum [Elbahnasy JU1998]Elbahnasy found that favourable factors as (LIP>70, infundibular length < 3cm & width > 5cm) All 3 all clear vs 16% if noneBut other studies show conflicting result

Any way to improve SFR in ESWL of LPS?Pace JU 2001Percussion , diuresis and inversion (PDI)SFR 40% (PDI) vs 3% (observation gp)

ESWL vs PCNL vs URSLPCNL vs ESWL : Lower Pole I [Albala JU2001]Prospective multicenter RCT , LPS < 3cm, SFR at 3mSFR: PCNL (95%) vs ESWL (37%)Complication: PCNL (23%) vs ESWL (12%) [insignificant]Conclusion: ESWL = PCNL for treatment lower pole stone < 10 mmPCNL should be indicated for LPS > 10 mm

URSL vs ESWL: Lower Pole II [Pearle JU2005]LPS < 1cm, SFR at 3mSFR: 50% (URS) vs 35% (ESWL)SFR: URSL 15% better than ESWL (not significant)Conclusion: ESWL = URSL for LPS < 1cmESWL has shorter txn time & recovery, better acceptance Thus URSL can be offered if ESWL failed as Lower morbidity than PCNL

Counseling LPS < 1cm:Offer ESWL as less invasiveLPS 1-2cm: PCNL, RIRS, ESWL are all acceptable optionsURSL or PCNL : less depend on lower pole anatomyLPS > 2cm: PCNL : outcome independent on stone size and renal anatomy

Lower pole stone

Calcyceal diverticulum stone

What is calyceal diverticulum?Congenital in originNon-secretory urothelial-lined compartments that communicate with collecting systemPt of communication often very narrow25% associated with stone, which will not passOther than treating stone obliteration of diverticulum during PCNL is needed

What is the SFR?ESWL 30%URSL + incision 70%PCNL + obliterateion90%

If ESWL failed to clear fragment , why?Calyceal diverticulumStone is too hard (ca oxalate monohydrate)

Horseshoe kidney stone

Horseshoe kidneyPrevalence: 1 in 400Pathology: abnormal medial fusion of the metanephric blastema failure of ascent and rotation of kidney (by IMA)Anatomical difference: Kidney in more caudal positionRenal pelvis is anterior to all calycesUreter insert high and lateral on renal pelvisCalyces point posteriorly , lower pole calyces point caudal and medially

ManagementESWL: Reasonable 1st line treatmentProblem: Difficulties in stone location (medial rotation , bowel gas, bone ) Impairment of drainage (dilated collecting system, urinary stasis & high insertion of ureter) URSL: For small sympotomatic stone not responding to ESWLFlexible instrument for tortuous ureter & complicated intra-renal anatomyReasonable SFRPCNL: For stone >2cm , failed ESWL & URSLPuncture: Upper pole posterior calyx Tract is more medial (increase risk of bowel injury , less pulmonary injury) Use flexible instrument to reach lower poleSFR: 70%

Ureteric stone

PresentationSudden onset of severe Flank pain that is colicky (waves of increasing severity are followed by a reduction in severity, but it seldom goes away completely)It may radiate to the groin as the stone passes into the lower ureterPatient moves around, trying to find a comfortable position

InvestigationBldMSUDip stick hematuriasensitivity for detecting ureteric colic~95% on the first day of pain,85% on the second day65% on the third and fourth dayspregnancy test in premenopausal women

NCCTGreater specificity (95%) & sensitivity (97%) for dx of ureteric stoneCan identify other non-stone cause of loin painNo contrast injection need (RFT)Faster (min)Cost equivalent to IVU in high volume centerIVU: Less radiation exposureShow level and degree of obstruction

NCCTCan also predict fragility of stone under ESWL:We observed that for calcium stones, the number of SWs to comminution was generally less than half the stone CT attenuation value in Hounsfield units (in those w/ 3-mm scans).This "half-attenuation rule" predicted the number of SWs needed to complete fragmentation for 95% of calcium stones (24/24 calcium oxalate monohydrate, 13/13 hydroxyapatite, 8/10 brushite stones). Saw K C et al Calcium stone fragility is predicted by helical CT attenuation values. J. of Endourology 2000 Aug;14(6):471-4

Mx of acute renal colicPain control: NSAIDMOA: by smooth muscle relaxation and reducing ureteral peristalsisCaution: Can affect RFT in patient with an already reduced functionEv: Cochrane review 2005Opioid vs NSAIDNSAID: lower pain score, less likely to require rescure medicationOpioid: more adverse effect (Nausea)If suboptimal pain controlAdd opioid analgesics e.g. dologesic/ pethidine

Prevent recurrent colicDouble-blind, placebo-controlled trialDiclofenac 50mg TDS x 7 days after discharge vs PlecoboResult:significant fewer colic (p < 0.01)difference was greatest during the first 4 treatment days

Conclusion: oral treatment with diclofenac was effective as short-term prophylaxis of new colic episodes, especially during the first 4 days, and reduces the number of hospital readmissions significantly. The stone passage rate appears not to be affected

Mx: Renal colicMedication: Pain relief Voltaren SR 100mg QD PO PRN (RFT) Pepcidine 20mg BD POPethedine 50mg Q6H IM PRNMedication: antibiotics ?

Do we need to over hydrate patient?Reason: increase urine output to Flush the stone out ?In fact, renal blood flow and UO fall in episode of obstructionExcess fluid excretion will cause greater hydronephrosis further impair peristalsis

Treatment optionsTailored to individual patient: (past health, obesity, stable clinical condition, responding to analgesics)1. Observation and medical therapies2. Ureteroscopy3. ESWL*2007 Guideline for the management of ureteral calculi. Gleen M. Preminger et al, Journal of urology 2007 dec vol 178; 2418-34*

METChances of spontaneous passage of stone

METFor stone < 5mm : no additional benefit with METFor stone 5-10mm , MET with alfa blocker is suggested when: No contraindication: Pain not controlledSepticDerange in RFTHypotensionBenefit: 29% more patient will pass their stone than control, less colicky & analgesic requirementRisk: 5% drop out due to hypotensionCa channel blocker: only 9% more (not significant) CCB vs AARB: 20% improvement in SPR with alpha blockers [MA Hollingsworth Lancet. 2006]Single use of corticosteroid is discourage

Time for stone passage: 4-6 weeksVast majority of trials were limited to patients with distal ureteric stonesTamsulosin is most studied , but all alfa blockers works well class effect (YILMAZ JU2005)MET using tamsulosin resulted in a $1132 cost advantage over observation (Bensalah et al. EJU 2008)MET in paed gp is not effective [Aydogdu JU2009]

Mechanis of ActionUreter SM relaxationAlpha-1 adrenergic receptor anatagonist in ureter in humans and animalsDensity of alpha1-anatagonist significantly higher than alpha2/ betaPrevalence of alpha1a (subtype) in humanInhibit basal tone, peristaltic frequency and ureteral contractionDecrease basal and micturating bladder neck pressureDecrease intraureteric pressureIncrease fluid transport abilityFacilitate spontaneous expulsion of ureteric stone

Definitive treatmentFor stone >10mm: No recommendation can be made for spontaneous passage (with/without therapy) Consideration factors: Stone size & locationRenal functionPresence of a normal contralateral kidneyTolerance of exacerbations of painJob and social situationlocal facilities

Stone removalBased on the: 2007 Guideline for the Management of Ureteral Calculi (joint EAU/AUA nephrolithiasis guideline Panel)Both ESWL and URS should be discussed as initial treatment optionsStone free rate, anaes, additional procedures and complicationsURS has better chance of stone free with single procedure , but higher complication ratesURS has greater stone-free rate for majority of stone stratifications

Stone free rate

Open and LapIn difficult situationsVery large impacted stonesMultipler ureteral stonesConcurrent conditions requiring surgeryLap Ureterolithotomy: Alternative to open surgeryLess successful in distal ureter then mid/proximalMedian stone-free rate: 88%

ConclusionThe more distal the stone, more in favor of URSSFR were consistently higher for smaller stonesURS SFR show less size dependenceThe data for middle ureteral calculi may not be as reliable as the overall outcome data (smaller sample size) A higher retreatment rate for SWL

What is cost effectiveness between URSL VS ESWL?Observation was least costly if no extra cost was incurred by failed observationUreteroscopy was less costly than ESWL for stones at all ureteral locations*all patients in URS groups were stented*URS as an out-patient procedure*Based on US health system

Lotan et al. Management of ureteral calculi: cost comparison and decision making analysis. Journal of Urology, 2002. Vol 167, 1621-29

When is drainage required?Pain that fails to respond to adequate analgesics or recurrent painAssociate fever and sign of sepsis (vitals, WBC)Impaired RFT (obstructed solitary kidney / bilateral ureteric stone) Obstructed stone > 4-6 weeksPersonal occupation reasons (pilot, control machine, driver, etc)

In obstruction : PCN or JJ?PCNAdvantage: Rapid decompressionNo manipulation of ureter to flare up sepsisLow failure rateMonitor UO from kidneyAccessible tract for future use

Disadvantage: Require radiologistInjury to other organsNephrostomy bag

JJDisadvantage: Takes time to performManipulation of ureter (sepsis and injury) Failure rate (impact stone)Fail to monitor UO NO accessible tract

Advantage: Performed by urologistAble to dilate ureter for future txnNO risk of injury to other organInternal drainage

Management of stone with PUJO

What is the management of stone with PUJO?Either percutaneous endopyelotomy or open reconstructive surgeryTransureteral endopyelotomy with Ho:YAG laser endopyelotomy Incision with an Acucise balloon catheter

Treatment of pediatrics stones

Investigation: < 1% of stone in patient 40%NCCT & IVU : detect 95% of stones (rarely need sedation)Provide anatomical and functional infoMRU: Cannot be used to detect a urinary stoneProvide detailed information of anatomy , the location of an obstruction or stenosis in the ureter, and the morphology of renal parenchymaUrine: serum chemistry and 24-hour urine collectionsIdentify underlying pathology: VURPUJONeurogenic bladder or other voiding difficulties

Txn: WWSpontaneous passage of a stone is more likely to occur in children than in adults< 5 mm are likely to pass spontaneously in up to 98% of paediatric patientsUse of MET is not proven in paed age gp

Txn: ESWL vs URSLIndications for ESWL (same as adults) stones with a diameter up to 20 mm are ideal casesGA need: 30-100% (age and type of lithotriptor) URS: primary / after failed ESWL Semirigid URS: 4.5 and 6.0 F Flexible URS: 5.3 FESWL: less efficient (cystine, brushite, Ca oxalate and anatomic abn)

What are stone-free results for pediatric patients?The very small number of patients in most groups, particularly for URS, makes comparisons among treatments difficultSWL may be more effective in the pediatric subset than in the overall population, particularly in the proximal and mid ureter Stone-free rate: 67-93% (short term studies)57-92% (long term FU studies)Retreatment rate: 14-54 %Need for ancillary procedures: 7-33 %Residual fragments should be closely FU

Ureteral stoneSpontaneous passage: 98% of

ESWL for ureteric stoneTxn of choice for proximal ureteric stoneDifficult case:>10mm , impacted stoneCa oxalate monohydate / Cystine Unfavourable anatomyStent is rarely needUreteral pre-stenting: decrease SFR after initial txn (retreatment rate: 12-14%)

PaediatricESWL may be more effective in mid & lower ureter

Stones in pregnancy

Physiological changeIncrease cardiac outputIncrease in vascular volume, renal output (+60%), GFR (+40-65%)1cm kidney size increaseIncreased rate of filtered Cr/Ur/Na/Ca/urateDecrease Serum Cr level HypercalciuriaIncrease intestinal Ca absorptionIncrease renal Ca filtrationIncrease in 1,25OH-D3 produced by placentaSame incidence of stone as increased inhibitors (e.g. citrate, Mg, glycoprotein)More alkaline urine due to respiratory alkalosisIncidence of ureteric stone: 1 in 2000Most in 2nd or 3rd trimesterSignificant risk of pre-term labour

Differential diagnosis of flank painPhysiological hydronephrosisUreteric stonePlacental abruptionAppendicitisPyelonephritisAll other cause of flank in non-pregnant women

Physiological changesPhysiological dilation of upper tractOccurs between 6th and 10th weeks (7weeks)Disappears 4-6 weeks after delivery90% right hydronephrosis at 3rd trimesterRight side predominantProgesterone with ureteral smooth muscle relaxationUterine dextrorotationCompression by ovarian and uterine veinProtection of left ureter by sigmoid

UltrasoundFirst line investigation: Sp 34%; Sn 86%Cannot differentiate physiological vs pathological dilationDilation up to pelvic brim: physiologicalDilatation below pelvic brim : distal obstruction1st trimester: right

Effect of radiationCongenital malformation: reduced head circumference/ microcephaly, hypoplasia of the genitalia, hypospadia, micropthalmia, cataractIU growth retardationMental retardationMiscarriageCancer risk (leukaemia) Mutagenic effects (inherited disease in offspring) Fetus most at risk : 4-10 week (1st trimester)Radiation dose > 150mGy significant increase risk of malforationRadiation dose < 100mGy unlikely to have adverse effectRadiation dose < 50mGy negligible effect (National Council on Radiation Protection) Majority of diagnostic procedure did not involve fetal exposure >50mGy (5000mrad)1 min fluoroscopy time (2mGy / 200mrad)X-ray = 1mGy/radiographAmerican College of Obstetritian and Gynecologists guideline Exposure to X-ray during pregnancy is not an indication for therapeutic abortion

Thus for radiation dose > 150mGy: 100 KUB88 IVP (6 shot)12.5 CT abd , 4 CT pelvis250 times JJ insertion

However, every healthy mother3% risk of birth defect15% for miscarriage4% prematurity4% growth retardation1% mental retardation / neurologic developmental problems(Brent RL, Mettler FA. Pregnancy policy. AJR 2004: 182: 819-822)Need to explain that the baby is not guaranteed to absolutely healthy after x-ray explosure

If USG not adequate ? What can be done3 shot IVU: plain, 30s, 20min Low dose CT MRU

IVUTaken plain, 30s, 20min (3 shots IVU) Use high sensitivity film, reduce aperture, digital radiology, lead apron for the side of health kidneyRadiation exposureOverlap with fetusSuboptimal film quality

NCCTHigh dose of irradiationAvoid in pregnancyLow dose CT with average radiation ~700mrad (7mGy) (Wesley, J of endourology 2007)

MRUT2 weighted imageSensitivity and specificity (100% for decting ureteric stone)Patient needs to stay still in the machine in a period of time in frank painStone as filling defectNot advised in the course of 1st trimester (Louca 1999)High resolution MRI available

MesssageAvoid all radiation at 1st trimesterUse US as first line imaging modalityAlthough estimated risk of diagnostic radiation during pregnancy is low, particularly 2nd and 3rd trimester, need to balance the risk of radiation and risk of untreated obstruction

Management of renal colicImaging to confirm the diagnosis1st Line : Hydration + analgesia +/- antibioticsIf physiological: usually not require stenting /PCNAnalgesiaParacetamol can be used with no riskCodeine contraindicated at 1st trimester; can be used episodically during 2nd/3rd trimesterMorphine with short duration to avoid maternofetal dependence, growth delay, prematurely induced labour; avoid at the beginning or or during laborNSAID : avoid for premature closure of ductus arteriosus, pulmonary HT, delay or prolong labour, bleeding during deliveryAlpha-blocker & CCB : unknown risk in pregnancy

Definitive65% pass their stone during pregnancy50% of the remaining pass after deliveryRelief obstruction: JJ or PCNunder LA + USG or GA + limited fluroscopyProblem: worsen irritative LUTS & repaid encrustation JJ need to be change 4-8 weeksIndication of treatmentintractablepain,nausea,vomiting,febrileurinarytractinfections,obstructiveuropathy,acuterenalfailure,sepsis,andobstructionofasolitarykidneyTreatment of stone: ESWL : cotraindicatedPCNL: not advice for pt positioning & fluroscopyURSL: safe and effective in all trimester , SFR 70-100%

AntibioticsSafe: Penicillin: OK Cephalosporin: OKMarcolide - Erythromycin (bacteriostatic): OK

Use with cautions: Nitrofurantoin: avoid in third trimester Fetal hemolytic anemia in G6PD deficiency motherhepatotoxicity, lung toxicity, inadequate urine concentration if GFR

Contraindicated: Fluoroquinolone (bacteriostatic): contraindicated as toxicity to fetal cartilage and joints, tendon damage

Chloramphenicol: contraindicated in third trimester as grey-baby syndrome

Tetracycline (bacteriostatic): contraindicated as hepatotoxicity, deposit in teeth and boneThiazide: fetal thrombocytopenia(not to be used)Allopurinol / D-penicillamine: fetal malformationPyridium: OK

Ureteral stentsUnder LA / US guidanceAllows return to normal activtiesCan be difficult to be placed (trigone deformed by uterus, hyperemic mucosa)Bladder irritation, risk of displacement due to dilation of upper tract, VUR causing back pain and pyelonephritisAvoid incrustation by changing every 4-8weeks, increase fluid intake, control Ca intake, treat UTI

PCNLA, US guidanceRisk of PCNRisk of encrustation; change 4-8 weeksEsp for very septic patients

URSLRisk of procedure: radiation/ureteric injury/ vascular injuryReduce discomfort from obstructionUnder locoregional anaesthesiaUreters dilated alreadyUse laser rather than EHL ( may induce labour) or ultasonic lithotriptor (hearing damage)

ESWL: contraindicated by fetal damage/radiationPCNL: contraindicated by difficult position, prolonged anaesthesia/high radiation / induce labour

Residual stones and fragments

CIRFClinically insignificant residual fragmentsMost commonly seen after ESWLMost common site: Lower calyxNCCT show small fragments > KUBEAU 2010:=5mm called residue stoneInfection stone:2.2yr, 78% of stone fragment have progressionCalcium stone: 6yr FUStone growth: 26%Recurrent stone formation: 15%*

Recommendations

General recommendations on stone treatmentInfectionsAnticoagulation and stone treatmentPacemakerHard StonesRadiolucent stones

InfectionsUrine test should always be carried outDipstick sufficient in uncomplicated caseIf infection and obstruction , drainage for several days before staring active intervention

AnticoagulationESWL , PCNL and open surgery contraindicatedURS can be done with less morbidityReduced risk of throboembolic complications

PacemakerCan be treated with ESWL provided that cardiologist is consulted beforeImplanted cardioverter defibrillators need to be de-activated during ESWL

Hard stonesBrushite or Ca oxalate monohydratePCNL for ESWL resistent casesChemolytic treatment for brushite stone

Special problems

Recurrence preventive treatment

How can stone be prevent?High fluid intake: 24-hour urine volume should exceed 2000mlProtective by reducing urinary saturation of Ca ,oxalate & urateProlong time to stone recurrence (from 2 to 3 years)Reduce risk of stone recurrence (12% vs 27%)One large study found a risk reduction of 29% in patients with a higher fluid intakeCurhan et al New Engl J Med 1993; 328: 8338Juice: Grapefruit juice increase risk (high oxalate)Orange juice beneficialCranberry juice no effect

Dietary calcium & ca supplement?Low dietary Ca intake is asso with higher risk of kidney stone [Borghis RCT (NEJM 2002) and Curhams large scale epidemiological studies (NEJM 1993)] Ca intake => absorption of oxalate in GI tract (due to decreased binding with Calcium) => urine oxalate excretion => Ca oxalate saturation of urine increases rapidly with small increase in oxalateNormal Ca diet for most people (1000 mg/day)Moderate Ca restriction for absorptive hypercalciuriaCa supplement: Small risk of inducing kidney stone with Ca supplement vs no Ca supplementNot recommended except in cases of enteric hyperoxaluriaFor those who need supplement , consuming supplement with meal or with oxalate-containing food would reduce risk

Dietary factorsOther dietary modification to reduce stone formation Low sodium : should not exceed 5 g/dayLow animal protein (0.8-1 g/kg/day)Vitamin C not > 500mg to 1g /day (precursor of oxalate)Small quantities of wineVegatatarian diet : alkaline content High fructose induce hypercalciuria, hyperoxaluria and hyperuricosuriaReduce soft drinksUrate

Dietary factorsFood rich in oxalate: Wheat bran, Rhubarb, spinachCocoa, Tea leaves, NutsFood rich in urate: Calf thymusLiver, kidney Poultry skinHerring with skin , sardines, anchovies, spratsExcess animal protein result in: HypocitraturiaLow pHHyperoxaluriaHyperuricosuriaHigh Na intake result in: Ca excretion (reduce tubluar reabsorption) urinary citrate (Loss of bicarbonate) effect of thiazide on urinary caCombine Na and animal protein restriction rate of Ca stone formation

MedicationPharmacological treatment should be instituted only when the conservative regimen has failedThe choice of drug therapy should be based on the stone analysis and on the appropriate biochemical investigationsThere are only three drugs with sufficient evidence on stone prevention: thiazides in hypercalciuriaallopurinol in hyperuricosuria postassium citrate in hypocitraturia Metaanalysis of RCT medical therapy reduces 20% of CaOx stone recurrence(Pearle, Pak J Endourol 1999)

Ca stones

What is suggested treatment for patients with specific abnormalities in urine composition?

What is the medical treatment for urate stone?

ThiazideHydrochlorothiazide (25-50mg QD/BD), bendroflumethiazide, trichlorothiazide, Indapamide MechanismIncrease Ca reabsorption in proximal and distal parts of nephron oxalate excretion ( intestinal ca absorption)SE: Hypokalaemia, hypocitraturia and hyperuricosuriaLoss of K should be replaced by K citrate 3.5-7mmol BD (K citrate >>> KCl )EAU Indications: hypercalciuria

Alkaline citratePotassium citrate (EAU), Na K citrate, Na citrate, K Mg citrate, KHCO3, NaHCO3Mechanism of action.Alkalinizing salt increase urinary pH increases the excretion of citrate reduce the supersaturation with calcium oxalate and calcium phosphate increase the inhibition of growth and aggregation (agglomeration) of the corresponding crystal phasesSE: GI upset, hyperkalaemia (!CRF)Compliance: ~50%Indications: hypocitraturiaEv: 2 RCT: K citrate significant reduced recurrence rate vs Na citrate

OrthophosphateVery weak evidence, NOT 1st line choiceInsufficient evidence to recommend its useMechanism of action.reduce the synthesis of 1,25(OH)2-D vitamin. decreased absorption of calcium reduced calcium excretion; reduced resorption of bone increased phosphate excretion, increases urinary citrate and pyrophosphate (inhibitor of Ca oxalate and Ca PO4 crystal growth)SE: Diarrhoea, abdominal cramps, nausea and vomitingThe possible effect on parathyroid hormone needs attention Compliance: good

MagnesiumNot recommended as monotherapy Combination with thiazide might prove usefulMechanism of actionformation of complexes between magnesium and oxalate, thereby reducing the supersaturation with calcium oxalate.Inhibit the growth of calcium oxalate / phosphate crystals citrate excertionSE: Diarrhoea, CNS disorders, tiredness, sleepiness and paresis Compliance 70-80%

AllopurinolIndication: hyperuricosuric Ca oxalate stoneuric acid stoneMechanism of actionReduced salting-out effectDecreased risk of uric acid or urate crystals as promoters of calcium oxalate precipitation Complex formation between colloidal urate and macromolecular inhibitors, and/orReduced excretion of oxalateSE: Steven Johnson SyndromeNo effect in patient without hyperuricosuriaCompliance?

Pyridoxine (Vit B6)Co-enzyme pyridoxal PO4 increase transamination of glyoxylate ?affect endogenous production of oxalateUse together with orthophosphate to tx primary hyperoxaluria Type I or idiopathic hyperoxaluriaNo RCT to show efficacy, but recommended for primary hyperoxaluria Type 1

Enteric hyperoxaluriaPatients with intestinal malabsorption of fatAfter intestinal resectionJejunoileal bypass for txn of obesityCrohns diseasePancreases insufficiencyLoss of fat Calcium bind to fatOxalate absorption hyperoxaluriaHypocitraturia because loss of alkaliUrine: low pH, low ca, low volume

TreatmentRestricted oxalate-rich foods & fat Ca supplements : enable ca oxalate complex formation in the intestineCa should be given at meal teimsOxalate-binding agents: marine colloid (Oxabsorb) Increase fluid intakeAlkaline citrate urinary pH and citrate

RecommendationsCa and oxalate influence the supersaturation with equal power essential to correct abnormalities of both variablesIncomplete distal RTA : given K citrateIn absence of common biochemical risk factors: water load had +ve effect on supersaturation and crystallisation

Intracorporeal energy forms

Outline Rigid Ballistic lithotripsyUS lithotriptorFlexibleEHLLASER

LithoclastBallistic (Pneumatic) lithotripsyCompressed air from an external supplyFires to a metal projectileKinetic energy delivered to the probe and then fragment the stone by Jackhammer effectVs electrokinetic lithotriptorSame fragmentation, retropulsion, safety marginEKL has heavier handpiece, but cheaper

Fragmentation rate 73-100%Avoid bowing of the probe to reduce power lossThere is a pneumatic disintegrating probe for flexible scopesSafe on ureter with perforation rate

LithoclastProsCheap in maintenanceEffectiveSafeConsRetropulsionNeed rigid instrumentFragment to larger piecesFragments not removed (except Lithoclast master)

Electrohydrolic lithotripsyUnderwater spark plugVoltage/ current to two concentric electrode with different voltage polarities, insulated and 1mm apartElectrically generated electric sparkMomentary production of heat in a localized area, causing the irrigant (water) to vaporize and form a gas bubbleExpansion and collapse of bubble generates shock wave in 1/800 secondSymmetrical (~1mm): strong secondary shockwaveAsymmetrical (~3mm): microjetsProbe at 1mm from stone (shockwave not focused)

EHLProsEffectiveUse in flexible instrument, as small as Fr 1.6Relatively inexpensive machineConsPotentially damage to surrounding tissue(ureteric perforation risk 17.6%)May need to revise the probe for hard stonesResidual stone fragments (3 month stone free rate ~84%)Work worse on smooth stone surface

US lithotriptorUS generator transmitting US waves to a hollow probe resulting vibration of the probe tipProbe tip causes the stone to resonate at high frequency and breaksDrilling or grinding action for stone fragmentationNormal tissue does not resonate less damage; but heat from the tip could damageNeed good irrigation system to cool the probeAllows suction of stone fragmentsAvoid use in pregnant women in URSL as unknown risk of hearing damage to fetusHigh temperature of the probe causing risk of ureteric injury, but reported to be good for steinstrassFragmentation rate 69-100%

US lithotriptorFactors affecting stone fragmentation efficacy (Campbell)chemical composition of the stone (cystine, calcium oxalate monohydrate, and uric acid being the most resistant) SizeDensitySurface structure (worse if smooth)

US lithotriptorProsSafeRemove stone fragmentsLess likely for retropulsionConsRelatively slower fragmentation (better combine with lithoclast master)Cost for probe breakageRigid instrument

What is cyberwand?Dual ultrasonic lithotriptor because it employs two separate ultrasonic probes that vibrate at two different (high and low) frequencies via one hand-piece to improve efficacyInner probe with high frequency, for larger stones Outer probe with low frequency, for small stonesWith suckerOne pedal

Laser

LASERLight Amplification by Stimulated Emission of RadiationCoherence (light in parallel), Monochromacity (in same wavelength), Collimation (in phrase)Photoacoustic effect : generation of shockwave by creating plasma bubbles and collapsesPhotothermic effect: vaporization of stone by heat

LASERPulsed laser : to keep stone vaporization but decrease heat dissipationTwo form of lasers in stone fragmentationPulsed dye laser (Coumarin green dye)1us duration, 504nm wavelengthAbsorb by stones except cystine but not tissue, poor with calcium oxalate monohydrateCoumarin dye is a toxic disposableHigh costFragmentation rate 80-95%Warm up time 20min

LaserHolmium:YAG laserPulse duration 250-350us (produce elongated cavitation bubble with weak shockwave)Wavelength: 2140nmAbsorb by water, zone of thermal injury 0.4mmStone fragmentation mainly by photothermal effectWork on all stonesFragmentation rate 91-100%More compact machine, 1min warm up time

Holmium:YAG LaserProsWork on all stonesCan fragment to tiny fragmentsSafe for surrounding structuresLess retropulsionFlexibleConsExpensive machineMay need longer time for fragmentationNeed eye protection(damage cornea if

Alexandrite laserSolid state laserNOT a pulsed-dye laserWavelength 750nmStone fragmentation rate 50%Complication of ureteric perforationFOR REMOVAL OF SKIN TATTOO

Laser SafetyWarning signs in operating theatreWear gogglesCheck if aim beam intactOperate the laser when the fiber is inside patients bodyStart from low setting (0.6J, 6Hz)Keep >2mm from urotheliumKeep fiber tip in view at all timesDo not discharge the laser fiber inside the working channel or on guide wires and basketsDo not have one person controlling the fiber and another the foot pedalDo not pass the fiber tip through the back wall of stones

Factors affecting laser fragmentation efficacy (Christian Seitz,EU 2007)Position : distal ~95%; proximal ~75%Impaction for upper ureteric stone (86% vs 67%)Independent onSizeCompositionPresence of hydronephrosisImpaction for lower ureteric stone

Fragments after lithotripsy: Active retrieval or Spontaneous passage?Oscar Schatloff (JU, 2010)

RCT, 60 patients with URS + Holmium laserIntra-op fragments retrieval by grasper vs exhaustive lithotripsyHigher rate of unplanned medical or ER visit 30% vs 3% without fragments retrievalRehospitalization / ancillary treatment, stone free rate worse but not significant

Upper ureteric stonesPrefer Holmium:YAG laserHigher stone clearance rateVs EHL : 100% vs 67%(Teichman, 1997)Vs lithoclast : 96% vs 70% (Sun, 2001)(RCT showed similar fragmentation but decreased retropulsion, Garg 2009)US lithotriptor need larger URS and prior dilation. Also potential problem of heat generation from probe and retropulsionSafe on ureterProduce fragments ~2mm vs lithoclast, pulsed dye laser or EHL (Teichman, JU1998)

Bladder stonesNo good study comparing different modalitiesRazvi (Journal of endourology, 1996)Mechanical lithotripsy 90% - stone too hard, breakage of lithotriteUS lithotripsy 88% - stone too hardEHL 63% - stone too hard, hematuriaLithoclast 85% - ineffective probe contact, prostatic channel bleeding obscuring view

Bladder stone