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Key Features

  • Typically develops during the fifth to seventh week of pregnancy

  • Occurs in 1 of 5000 live births

  • Slightly more common males

  • Almost 50% of babies have additional defects, often in association with a particular syndrome

  • Defects are generally classified as

    • Low (rectoperineal malformation) where the rectum may not connect to the anus, a membrane may be present over the anal opening, or the anal opening may be narrow or misplaced

    • A high lesion is classified where the rectum may connect to part of the urinary tract or the reproductive system through a fistula

Clinical Findings

  • Low imperforate anus

    • Infants do not pass meconium

    • Greenish bulging membrane obstructing the anal aperture may be present

    • A skin tag shaped like a "bucket handle" is seen on the perineum of some males below which a stenotic aperture can be seen

    • Aperture is sometimes surrounded by normal anal musculature

    • However, in many cases, the aperture is a rectoperineal fistula and the anal musculature is displaced posteriorly or is absent

  • High imperforate anus

    • Physical examination usually shows no anal musculature

    • Rectoperineal, rectovesicular, rectourethral, or rectovaginal fistula

    • Hypoplastic buttocks

    • Cloacal anomalies

    • Evidence of distal neurologic deficit (sometimes)


  • Clinical


  • Before attempting corrective surgery, the complex anatomy and neurologic function must be fully evaluated

  • Perforation of the anal membrane is a relatively simple surgical procedure

  • A diverting colostomy is usually performed to protect the urinary tract and relieve obstruction

  • After reparative surgery, only 30% of patients with high imperforate anus achieve fecal continence

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