Pediatric Surgery: Anorectal Malformation

Anorectal Malformation (ARM)

Types

  • Imperforate Anus: Complete Obstruction
    • High – Above Levators (Rectal Gas Seen Above the Coccyx)
    • Low – Below Levator (Rectal Gas Seen Below the Coccyx)
  • Male Fistula:
    • Perineum
    • Urethra (Bulbar or Prostatic)
    • Vesicular/Bladder Neck
  • Female Fistula:
    • Perineum
    • Vestibula
    • Persistent Cloaca

Associated Anomalies

  • Most (50-60%) Have ≥ 1 Associated Anomaly
  • Genitourinary Anomalies Most Common (40-50%)
  • Cardiovascular Anomalies Second Most Common (30-35%)
  • VACTERL Syndrome
    • Vertebrae
    • Anorectal
    • Cardiac
    • TA/TEF
    • Renal
    • Limb Anomalies
  • Currarino Triad: Imperforate Anus, Sacral Defect (Hemisacrum) & Presacral Mass
    • Strong Familial Trend

Imperforate Anus 1

Perineal Fistula 2

Rectobladder Neck Fistula 2

Rectovestibular Fistula 2

Persistent Cloaca 2

Diagnosis

  • Initial Evaluation is a Thorough Perineal Inspection
  • Wait 20-24 Hours for Adequate Evaluation (Exam & Imaging)
    • Intraluminal Pressure Must Build for Meconium to Push Through a Fistula
      • High Imperforate Anus – No Meconium Seen
      • Perineal Fistula – Meconium in Perineum
      • Urethral/Vesicular Fistula – Meconium in Urine
    • Rectum is Collapsed Prior to 24 Hours Due to Muscle Tone
  • Evaluate with Lateral Colostogram
    • Distal Rectum Must Be Fully Distended for Adequate Image
  • Sacral Ratio:
    • Quantifies the Degree of Sacral Hypo-Development Based on XRay
    • Distances:
      • AB: Iliac Crest (A) to SI Joint (B)
      • BC: SI Joint (B) to Tip of Coccyx (C)
    • Ratio = AB/BC
    • Ratio > 0.7 Indicate a Low Risk of Fecal Incontinence
  • Use First 24 Hours to Evaluate for Associated Anomalies: Renal US, Spinal US, Echocardiogram, etc.

Treatment

  • Imperforate Anus:
    • High: Colostomy & Delayed Repair in 2-3 Months
    • Low: Posterior Sagittal Anorectoplasty (PSARP)
  • Fistula:
    • Perineal Fistula: Anoplasty
    • Other Fistulas: Colostomy & Delayed Repair in 3-6 Months
  • Persistent Cloaca: Colostomy & Consider Urinary Drainage

References

  1. Gupta MD, M P G, Mukhopadhyay S, Yusuf J, Tyagi S. Baller-gerold syndrome a rare cause of heart-hand syndrome. ISRN Cardiol. 2011;2011:962084. (License: CC BY-3.0)
  2. Levitt MA, Peña A. Anorectal malformations. Orphanet J Rare Dis. 2007 Jul 26;2:33. (License: CC BY-2.0)