Pedi gu review anorectal malformations


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Pedi gu review anorectal malformations

  1. 1. Anorectal malformation and cloaca Pediatric GU Review UCSD Pediatric Urology George Chiang MD Sara Marietti MD Outlined from The Kelalis-King-Belman Textbook of Clinical Pediatric Urology 2007 (not for reproduction, distribution, or sale without consent)
  2. 2. Introduction <ul><li>ARM (anorectal malformations) occur in 1 in 4,000 to 1 in 5,000 </li></ul><ul><li>Cloacal anomalies 1 in 50,000 </li></ul><ul><li>Pena and Hendren ushered in the modern era of ARMs with a posterior sagittal approach 1980s </li></ul><ul><li>High association of urological abnormalities and spinal dysraphisms with ARMs </li></ul>
  3. 3. Spectrum of abnormalities <ul><li>1829 Mayer recognized association of vaginal agenesis and other congenital anomalies; Hauser and Schreiner emphasized association of vaginal anomalies with skeletal/renal anomalies </li></ul><ul><li>1/3 of patients have upper tract anomalies </li></ul><ul><li>Similar to these associations, VACTERL </li></ul><ul><li>Presentation varies with some children with abnormal antenatal u/s but most with abnl neonatal exam </li></ul><ul><ul><li>Absent perineal orifice (anus usually or vagina); or abdominal mass from hydrometrocolpos or urinary retention </li></ul></ul><ul><ul><li>Patients may fail to evacuate feces/urine or may leak urine </li></ul></ul>
  4. 4. Spectrum <ul><li>ARMs include: stenosis, ectopic, covered, imperforate (low/high), atresia </li></ul><ul><li>Female vaginal anomalies associated with ARM </li></ul><ul><ul><li>Congenital obstruction, agenesis, duplication anomalies </li></ul></ul><ul><ul><li>UG malformations </li></ul></ul><ul><ul><li>Common association is imperforate anus with fistula to vestibular or vaginal regions </li></ul></ul>
  5. 5. Spectrum <ul><li>Males: hypospadias, urethral duplication, urethral agenesis, urethral stricture, PUV; imperforate anus with fistula to bladder/prostatic or bulbar urethra </li></ul><ul><ul><li>Urethral fistula without imperforate anus is rare but occurs </li></ul></ul>
  6. 6. Embryology <ul><li>ARMs arise from a short cloacal membrane associated with deficient dorsal cloacal anlage </li></ul><ul><li>Urorectal septum functions as mesodermal tissue wedge which divides the cloacal membrane into the UG and anal membrane </li></ul><ul><ul><li>Differential growth causes anal membrane to be displaced caudally (pectinate line is level of anal membrane) </li></ul></ul><ul><li>Paidas and Pena propose a different theory with maldevelopment of Rathke fold and Tourneux fold </li></ul>
  7. 7. Embryology <ul><li>Paramesonephric ducts </li></ul><ul><ul><li>Caudally fuse to become the uterus </li></ul></ul><ul><ul><li>Cranially fallopian tubes </li></ul></ul><ul><li>Mullerian aplasia represents the absence of the uterus and results from inadequate caudal progression of the ducts (distal structures are normal) </li></ul><ul><li>Various degrees of failure of paramesonephric duct fusion represent uterine anomalies </li></ul>
  8. 8. Imperforate Anus <ul><li>2 main classification systems </li></ul><ul><li>Stephens and Smith: </li></ul>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%)
  9. 9. Imperforate Anus <ul><li>Brock and Pena </li></ul><ul><ul><li>Colostomy required or not required </li></ul></ul><ul><li>Evaluation </li></ul><ul><ul><li>Detailed physical exam and then observation 18-24 hrs (can help determine level based on U/A-high lesion) </li></ul></ul><ul><ul><li>Presence of “bucket handle” abnormality or mid-raphe fistula=low </li></ul></ul><ul><ul><li>Perineal u/s, sinogram, MRI </li></ul></ul><ul><ul><li>Radiographically, >1cm between rectal puch and perineum=high lesion </li></ul></ul><ul><ul><li>Abdominal sonogram, VCUG, spinal sonogram, and PVR </li></ul></ul>
  10. 10. Imperforate Anus <ul><li>Patients with high lesion require neonatal colostomy; low lesion can be managed with neonatal PSARP </li></ul><ul><li>Goals </li></ul><ul><ul><li>Protect upper tracts </li></ul></ul><ul><ul><li>Ensure low-pressure urinary drainage </li></ul></ul><ul><ul><li>Minimize neurological defect from spinal pathology </li></ul></ul>
  11. 11. Imperforate Anus <ul><li>Patients may require CIC, cutaneous vesicostomy or spinal surgery </li></ul><ul><li>Type of colostomy is important </li></ul><ul><ul><li>Transverse colostomies are difficult to clean and decompress distally; loop colostomies are contraindicated from risk of fecal contamination of urinary tract </li></ul></ul><ul><li>PSARP at 1-6 months depending on other reconstructive issues </li></ul><ul><li>Colostomy closure once PSARP healed </li></ul>
  12. 12. Imperforate Anus <ul><li>Children who fail fecal incontinence are managed by dietary or pharmacological intervention </li></ul><ul><li>MACE may be required </li></ul><ul><li>Neonatal PSARP </li></ul><ul><ul><li>Foley to protect urethra </li></ul></ul><ul><ul><li>Electrical stimulation to identify anal sphincter </li></ul></ul>
  13. 13. Urological Problems with ARM <ul><li>Incidence of urinary tract structural anomalies is 35% </li></ul><ul><li>Recto-urinary tract fistulas are common </li></ul><ul><li>Non-fistula GU anomalies 60% high lesions and 25% low lesions </li></ul><ul><ul><li>Renal mortality 3.5% </li></ul></ul><ul><ul><li>Death from renal failure 6.4% high; 1.1% in low </li></ul></ul><ul><ul><li>Lesions threatening both kidneys 14% </li></ul></ul><ul><ul><li>VUR 33%; neurovesical dysfunction 25% </li></ul></ul>
  14. 14. Urological Problems with ARM <ul><li>Screening u/s for spinal dysraphism in infants </li></ul><ul><li>Dysfunctional voiding in 31% (high) and 5% (low) </li></ul><ul><li>In the absence of transabdominal dissection and significant retrovesical dissection, PSARP does not affect lower urinary tract function </li></ul><ul><li>Hyperchloremic metabolic acidosis may result from rectovesical/rectourethral fistula </li></ul><ul><ul><li>Need to create low, fully diverting colostomy and ensure effective urinary drainage </li></ul></ul><ul><ul><li>Treat with oral alkalinizing agents, IC, vesicostomy, or early anorectal reconstruction </li></ul></ul><ul><li>Vaginal problems can occur from scarring or primary vaginal anomalies; potential for impaired fertility </li></ul>
  15. 15. Cloaca <ul><li>Level of insertion of rectum is immaterial secondary to initial diverting colostomy </li></ul><ul><li>Configuration of UG sinus has tremendous surgical implications </li></ul><ul><ul><li>Short UG sinus-->total UG advancement </li></ul></ul><ul><ul><ul><li>UG sinus is tubularized to become urethra, vagina mobilized; short vagina may require flap </li></ul></ul></ul><ul><ul><li>Posterior cloaca is rare </li></ul></ul><ul><li>Protect upper tracts, maintain low-pressure drainage, normalize perineal anatomy, and minimize neurological defect </li></ul><ul><ul><li>Colostomy should be well position from lower midline in case of vesicostomy </li></ul></ul><ul><ul><li>-By 6-12 months most patients can undergo PSARUVP </li></ul></ul>
  16. 16. Cloaca <ul><li>Low UG sinus undergo advancement </li></ul><ul><li>High UG sinus-->cloacal disassembly and reassembly </li></ul><ul><li>Pena et al </li></ul><ul><ul><li>Common channel >3 cm=lower likelihood of having entire defect repaired by posterior sagittal approach </li></ul></ul><ul><ul><li><3 cm total UG sinus mobilization is reproducible and succesful </li></ul></ul><ul><li>Long term gynecological problems secondary to hematometra or hematocolpos </li></ul>
  17. 17. Urological Reconstruction <ul><li>ARMS have high risk for fecal/urinary incontinence </li></ul><ul><li>Must address both problems </li></ul><ul><ul><li>Avoid incidental appendectomy for potential Mitrofanoff or ACE </li></ul></ul><ul><ul><li>Imperforate anus surgery must be performed with indwelling catheter to avoid urethral injury </li></ul></ul><ul><ul><li>RU fistulae require fully diverting colostomy with short distal colonic limb to prevent ongoing contamination </li></ul></ul><ul><li>ARMs </li></ul><ul><ul><li>70% of children requiring urinary reconstruction ultimately required CIC </li></ul></ul><ul><ul><li>>40% of these patients required ureteral reimplantation and bladder augment; 22% BNR and 35% Mitrofanoff </li></ul></ul>
  18. 18. Urological Reconstruction <ul><li>Most neurovesical dysfunction and urethral strictures encountered in patients with ARMs are congenital (not iatrogenic) </li></ul><ul><li>VUR is usually bilateral </li></ul><ul><li>Ureteral reimplantation into dysfunctional bladder usually fails unless dysfunction controlled </li></ul><ul><li>Prompt and efficient decompression of obstructive hydro is essential </li></ul><ul><li>Similar risk for latex allergies </li></ul><ul><li>Combination of NV dysfunction of urethral stricture and RU fistula predispose to sepsis and hyperchloremic metabolic acidosis </li></ul><ul><li>A low, fully diverting colostomy is most protective </li></ul><ul><li>Patients with cloaca should never have their ARM and UGSM corrected separately </li></ul>
  19. 19. Renal transplantation <ul><li>Peritoneal dialysis is more difficult and may be impossible </li></ul><ul><li>Renal transplanation is extremely challenging and bladder pathology must be dealt with initially; vascular anomalies are also common </li></ul>