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Anorectal Malformation

  • Incidence: Occurs in 1 in 5000 live births, with a male predominance (58%).
  • Spectrum of conditions: Ranges from simple anal stenosis to persistent cloaca.

Embryology

  • Developmental defect: Failure of the urorectal septum to fully separate the cloaca into the urogenital sinus (anterior) and anorectal canal (posterior).
    • In boys: Fistula between the bowel and urinary tract.
    • In girls: Fistula between the bowel and vagina.

Anatomic Classification

  • Low, Intermediate, or High lesions based on the level of the rectal pouch in relation to the levator ani musculature.
    • Low lesions: Typically have a better prognosis.

Associated Anomalies

  • VACTERL association: Vertebral, Anorectal, Cardiac, Tracheoesophageal, Renal, Limb defects.
  • Genitourinary abnormalities:
    • Occur in 25%-60% of cases.
    • More common in high lesions (e.g., rectovesical fistula, cloaca).
  • Sacral and spinal anomalies:
    • Occur in one third of patients.
    • Poor prognosis for continence if multiple vertebrae are absent.

Diagnosis

  • Perineal inspection:
    • Boys: Look for a perineal fistula.
    • Girls: Look for a vestibular fistula or cloaca.
  • Imaging:
    • Renal ultrasound, voiding cystourethrography for urinary tract assessment.
    • Echocardiogram if cardiac defect is suspected.
    • Cross-table lateral x-ray to determine rectal pouch location.

Surgical Management

Low Lesions

  • Primary single-stage repair:
    • Boys with perineal fistula: Anoplasty.
    • Girls with vestibular fistula: Colostomy or primary repair.

Intermediate or High Lesions

  • Three-stage reconstruction:
    1. Diverting colostomy with mucous fistula to prevent contamination.
    2. Posterior sagittal anorectoplasty (PSARP):
      • Fistula division.
      • Pull-through of the terminal rectum to a normal anal position.
    3. Colostomy reversal after healing.

  • Laparoscopically assisted PSARP:

    • Minimally invasive approach with the potential to improve outcomes.

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Complications

  • Continence issues:
    • 75% of patients achieve voluntary bowel movements.
    • 50% of these may still experience soilage.
    • Constipation is a common sequela.
  • Bowel management program:
    • Daily enemas to reduce soilage and improve quality of life.

Prognosis

  • Good prognosis if:
    • Low lesion.
    • Normal sacrum.
    • Adequate bowel management after surgery.

Key Terms Highlighted:

  • Anorectal malformation
  • Perineal fistula
  • Vestibular fistula
  • Cloaca
  • Posterior sagittal anorectoplasty (PSARP)
  • Laparoscopic PSARP
  • Bowel management

Let me know if you need more details on any specific part or further explanations!