Anorectal malformation and cloaca

Pediatric GU ReviewUCSD Pediatric Urology

George Chiang MDSara Marietti MD

Outlined from The Kelalis-King-Belman Textbook of Clinical Pediatric Urology 2007

(not for reproduction, distribution, or sale without consent)

Introduction

• ARM (anorectal malformations) occur in 1 in 4,000 to 1 in 5,000

• Cloacal anomalies 1 in 50,000• Pena and Hendren ushered in the modern

era of ARMs with a posterior sagittal approach 1980s

• High association of urological abnormalities and spinal dysraphisms with ARMs

Spectrum of abnormalities

• 1829 Mayer recognized association of vaginal agenesis and other congenital anomalies; Hauser and Schreiner emphasized association of vaginal anomalies with skeletal/renal anomalies

• 1/3 of patients have upper tract anomalies• Similar to these associations, VACTERL • Presentation varies with some children with abnormal

antenatal u/s but most with abnl neonatal exam– Absent perineal orifice (anus usually or vagina); or

abdominal mass from hydrometrocolpos or urinary retention– Patients may fail to evacuate feces/urine or may leak urine

Spectrum

• ARMs include: stenosis, ectopic, covered, imperforate (low/high), atresia

• Female vaginal anomalies associated with ARM– Congenital obstruction, agenesis, duplication

anomalies– UG malformations– Common association is imperforate anus with

fistula to vestibular or vaginal regions

Spectrum

• Males: hypospadias, urethral duplication, urethral agenesis, urethral stricture, PUV; imperforate anus with fistula to bladder/prostatic or bulbar urethra– Urethral fistula without imperforate anus is rare but

occurs

Embryology

• ARMs arise from a short cloacal membrane associated with deficient dorsal cloacal anlage

• Urorectal septum functions as mesodermal tissue wedge which divides the cloacal membrane into the UG and anal membrane– Differential growth causes anal membrane to be displaced

caudally (pectinate line is level of anal membrane)

• Paidas and Pena propose a different theory with maldevelopment of Rathke fold and Tourneux fold

Embryology

• Paramesonephric ducts – Caudally fuse to become the uterus– Cranially fallopian tubes

• Mullerian aplasia represents the absence of the uterus and results from inadequate caudal progression of the ducts (distal structures are normal)

• Various degrees of failure of paramesonephric duct fusion represent uterine anomalies

Imperforate Anus• 2 main classification systems• Stephens and Smith:

Male Female

High Rectourethral fistula (81%)

RV fistula

Anorectal agenesis without fistula

Cloaca (86%)

Anorectal agenesis without fistula

Intermediate RB fistula (56%)

Anal agenesis without fistula

Rectovestibular fistula (54%)

Anal agenesis without fistula (21%)

Low Anocutaneous fistula (65%)

Covered anal stenosis

Anovestibular fistula (42%)

Anocutaneous fistula (30%)

Imperforate Anus

• Brock and Pena– Colostomy required or not required

• Evaluation– Detailed physical exam and then observation 18-24 hrs (can

help determine level based on U/A-high lesion)– Presence of “bucket handle” abnormality or mid-raphe

fistula=low – Perineal u/s, sinogram, MRI– Radiographically, >1cm between rectal puch and

perineum=high lesion– Abdominal sonogram, VCUG, spinal sonogram, and PVR

Imperforate Anus

• Patients with high lesion require neonatal colostomy; low lesion can be managed with neonatal PSARP

• Goals– Protect upper tracts– Ensure low-pressure urinary drainage– Minimize neurological defect from spinal

pathology

Imperforate Anus

• Patients may require CIC, cutaneous vesicostomy or spinal surgery

• Type of colostomy is important– Transverse colostomies are difficult to clean and

decompress distally; loop colostomies are contraindicated from risk of fecal contamination of urinary tract

• PSARP at 1-6 months depending on other reconstructive issues

• Colostomy closure once PSARP healed

Imperforate Anus

• Children who fail fecal incontinence are managed by dietary or pharmacological intervention

• MACE may be required • Neonatal PSARP

– Foley to protect urethra– Electrical stimulation to identify anal

sphincter

Urological Problems with ARM

• Incidence of urinary tract structural anomalies is 35%

• Recto-urinary tract fistulas are common• Non-fistula GU anomalies 60% high lesions

and 25% low lesions – Renal mortality 3.5%– Death from renal failure 6.4% high; 1.1% in low– Lesions threatening both kidneys 14%– VUR 33%; neurovesical dysfunction 25%

Urological Problems with ARM

• Screening u/s for spinal dysraphism in infants• Dysfunctional voiding in 31% (high) and 5% (low)• In the absence of transabdominal dissection and

significant retrovesical dissection, PSARP does not affect lower urinary tract function

• Hyperchloremic metabolic acidosis may result from rectovesical/rectourethral fistula– Need to create low, fully diverting colostomy and ensure effective

urinary drainage– Treat with oral alkalinizing agents, IC, vesicostomy, or early

anorectal reconstruction

• Vaginal problems can occur from scarring or primary vaginal anomalies; potential for impaired fertility

Cloaca

• Level of insertion of rectum is immaterial secondary to initial diverting colostomy

• Configuration of UG sinus has tremendous surgical implications– Short UG sinus-->total UG advancement

• UG sinus is tubularized to become urethra, vagina mobilized; short vagina may require flap

– Posterior cloaca is rare

• Protect upper tracts, maintain low-pressure drainage, normalize perineal anatomy, and minimize neurological defect– Colostomy should be well position from lower midline in case of

vesicostomy– -By 6-12 months most patients can undergo PSARUVP

Cloaca

• Low UG sinus undergo advancement• High UG sinus-->cloacal disassembly and

reassembly • Pena et al

– Common channel >3 cm=lower likelihood of having entire defect repaired by posterior sagittal approach

– <3 cm total UG sinus mobilization is reproducible and succesful

• Long term gynecological problems secondary to hematometra or hematocolpos

Urological Reconstruction

• ARMS have high risk for fecal/urinary incontinence• Must address both problems

– Avoid incidental appendectomy for potential Mitrofanoff or ACE– Imperforate anus surgery must be performed with indwelling

catheter to avoid urethral injury– RU fistulae require fully diverting colostomy with short distal colonic

limb to prevent ongoing contamination

• ARMs– 70% of children requiring urinary reconstruction ultimately required

CIC– >40% of these patients required ureteral reimplantation and bladder

augment; 22% BNR and 35% Mitrofanoff

Urological Reconstruction

• Most neurovesical dysfunction and urethral strictures encountered in patients with ARMs are congenital (not iatrogenic)

• VUR is usually bilateral• Ureteral reimplantation into dysfunctional bladder usually fails unless

dysfunction controlled• Prompt and efficient decompression of obstructive hydro is essential• Similar risk for latex allergies• Combination of NV dysfunction of urethral stricture and RU fistula

predispose to sepsis and hyperchloremic metabolic acidosis• A low, fully diverting colostomy is most protective• Patients with cloaca should never have their ARM and UGSM corrected

separately

Renal transplantation

• Peritoneal dialysis is more difficult and may be impossible

• Renal transplanation is extremely challenging and bladder pathology must be dealt with initially; vascular anomalies are also common