The urine sediment is of two types:

A. Organized sediment B. Unorganized sediment

Cells

Erythrocytes.

Leukocytes (pus cells).

Epithelial cells.

Casts.

Miscellaneous structures

Mucous threads.

Spermatozoa.

Parasites.

Fungus.

Tumor cells

Crystals.

Fat droplets.

1- Cells:

WBCs (Pus cell)

RBCs

N.= 2-3/HPF

Significance of Pus cells (pyuria)

•Physiological causes: (0-4 leukocytes/HPF) may be present in females.

•Pathological causes: - UTI

- Cystitis. - Prostatitis.

- Chronic pyelonephritis.- Renal stones.

-Renal tumors.

Epithelial cells

Squamous epithelial cells

Transitional epithelial cells

Distal urethra and vagina. mucosa of bladder, ureters and pelvis of kidney.

Significance:- Normally a few epithelial cells are seen in normal urine, more common in females and reflect normal sloughing of these cells.When these cells are present in large number along with leukocytes, they are indicative of inflammation.

2- Casts• They are cylindrical in shape with rounded ends (mostly).

• The basic structure of casts is "Tamm-Horsfall mucoprotein protein,

which secreted by tubular cells.• Cast are unstable & deteriorate with time specially in dilute &/or

alkaline pH.

• Essential materials for cast formation PH Acidic Mould Renal tubules Protein Tamm-Horsfall mucoprotein

Types of cast

a.Hyaline cast.

b.Cellular cast.

c.Granular cast.

d.Waxy cast.

e.Fatty cast.

Hyaline cast: It is basic protein cast. These are cylindrical, colorless homogeneous and transparent.• Hyaline casts can be present in low numbers (0-1/LPF) in

concentrated urine of normal patients, not always associated with renal disease. 

• Greater numbers of hyaline casts may be seen in association with proteinuria of renal (e.g., glomerular disease) or extra-renal origin (e.g., overflow proteinuria as in myeloma).

• In such cases it has been proposed that the presence of excessive serum protein in the tubular lumen promotes precipitation of the Tamm-Horsefall mucoprotein.

Cellular casts: most commonly observed in diseases which cause degeneration, necrosis or sloughing of tubular epithelial cells

It can be

Epithelial cast

Acute tubular necrosis.

Red cell cast )have a yellowish orange

color (

• Acute glomerulonephritis• Renal infarction.

Leukocytic cast

• Acute pyelonephritis.• Interstitial nephritis.• Acute glomerulonephritis

It is rarely possible to distinguish between epithelial casts and leukocyte casts

Granular cast: it can be of either

• Formation: from degenerating cells or solidification of plasma proteins.

• It’s common in advanced renal diseases as, chronic nephritis and amylidosis

Coarse granules

Fine granules

Waxy cast (Renal failure casts):

• Waxy cast are yellowish homogeneous,britle with irregular blunt or cracked ends( square cutted) and have high refractive index ( so more visible than hyaline under microscope).

• It’s common in chronic renal failure.

Fatty cast

• They contain fat globules of varying size which are highly refractile.

• Fat in the cast is cholesterol or triglycerides.

• They are passed in urine in the following conditions:• Nephritic syndrome.

• Fat necrosis.

3- Miscellaneous structures

A. Spermatozoa They are occasionally seen in normal urine of intact male animals. They have no significance.

B. Parasites Parasitic ova in urine sediment are from parasites in the urinary system or fecal contamination of the urine samples.

• The urine may contain;• Trichomonas vaginalis………..more common in females.• Dictophyma renal……………..kidney worm of dogs. • Cappillaria plica………………bladder warm of dogs and cats.

C. FungusCandida are budding yeast cells can be seen in urine in animals with UTI or contaminant.

D. Tumor cells : which having all the characteristics of malignancy may be seen singly or in groups in urine. These tumor cells could be from kidney, ureter, bladder and urethra.These cells are examined after staining of urine sediment.

1- Fat droplets Fat droplets are lightly tinged green, highly refractile, round bodies of varying size. Presence of fat in urine called "lipuria". * In most cats, lipuria appeared to some degree because the kidneys of cats contain a large amount of lipid.

 

Scattered fat droplets appeared in urine in the following conditions:1.Obesity.

2.Diabetes mellitus.3.Hypothyroidism.

2- Crystals: The type of crystals formed depends on urine pH

Acidic PH crystalsAlkaline PH crystals • Calcium oxalate.• Amorphous phosphate.

• Uric acid.• Triple phosphate

• Amorphous urate.• Calcium carbonate.

• Leucine.• Ammonium biurate.

• Tyrosine.

• Cystine.

1-Calcium oxalate Crystals

Calcium oxalate dihydrate crystals

Calcium oxalate monohydrate crystals

Significance It present in acidic and neutral urine.

It present in small numbers in the urine of healthy dogs.Ethylene glycol poisoning especially monohydrate form

oxalate urolithiasis.

2- Uric acid crystals

3-Amorphous urate crystals

They appear as yellowish brown granular precipitate in the form clump and dissolve on heating. When they are made of sodium

urate, they are needle like in the form of thorn apple.

Significance

They are passed more often in patients having gout

4- Amino acid crystals

1.Tyrosine crystalsDark and needle like. Often

found in small clusters or sheaves.

2. Leucine crystalsLarge spheroids with concentric striations

Significanceassociated with sever liver diseases in human, but not

been commonly found in animals.

3- Cystine crystals

Significance: There is a metabolic defect affecting the transport of cystine and other amino acids across the renal tubules. These animals are prone to the formation of cystine uroliths,(cystinuria)

1- Amorphous phosphate crystals

They can be present in large amounts but have no clinical significance.

2- Triple phosphate crystals (struvite crystals

prism like appearance with tapering sides and ends "coffin-lid”

It may be found in animals with struvite uroliths which are often associated with Staphylococcus urinary tract infections

3-Calciumcarbonate crystals

They are round with many lines radiating from their centers and may also have a short dumbbell-shape.

4- Ammonium biurate crystals (Ammonium urate)

They are brown and round with long spicules (thorn apple shape). These

spicules occasionally break off the main part of the crystal and appear

as small brown crystals with fine radiating lines.

Significance

1. Animals with liver diseases especially in those with portacaval shunts

1. In Dalmatians; due to altered purine metabolism in this breed.

Other crystals

1 -Sulphonamide crystals

2- Bilirubin crystalsWhen increased in no.

Indicate severe hemolytic anemia or severe liver or biliary disease.

3- Cholesterol crystals

They are large flat structures with distinct right angles. They may be rectangular but usually appear as two or more rectangles joined together. They are not commonly found and their significance is unknown, but they may be found in the urine of animals with previous urinary tract hemorrhage or degenerative diseases.

Sulfadiazine crystals