Anorectal Malformation

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What is an anorectal malformation?

Anorectal malformation is a term used to designate a series of congenital defects characterized by the absence of an anal opening. However, most of the time, the rectum is abnormally connected to the perineum or to the urogenital tract. Actually, only 5% of all cases suffer from a real blind rectum and half of that particular group suffers from Down syndrome.

Fifty percent of the cases have a urologic abnormality, 30% a vertebral one, 25% a spinal cord anomaly, 10% a cardiac condition that requires treatment, and 8% esophageal atresia.

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How do you determine the severity of the defects?

The malformation occurs in the form of a spectrum. On the good side of the spectrum are malformations relatively easy to repair, with an excellent functional prognosis. On the bad side of the spectrum, we see complex defects, such as cloacas and cloacal exstrophies, that require a specialized team of surgeons to repair; and the patients suffer from very serious functional sequelae, mainly related to bowel and urinary control as well as sexual and fertility problems.

Important prognostic factors include (1) characteristics of the sacrum, (2) presence or absence of tethered cord, and (3) specific type of malformation.

The functional prognosis in patients who receive an adequate repair and have normal sacrum and no tethered cord is:

In males:

• Perineal fistula: 100% chances of bowel control

• Anorectal malformation without fistula: 90%

• Rectourethral bulbar fistula: 85%

• Rectourethral prostatic fistula: 60%

• Rectobladder neck fistula: 15%

In females:

• Perineal fistula: 100% chances of bowel control

• Vestibular fistula: 93%

• Cloaca with short common channel (<3 cm common channel)

  • 70% chances of bowel control

  • 80% chances of urinary control

• Cloaca with a long common channel (>3 cm common channel)

  • 50% chances of bowel control

  • 20% chances of urinary control

(Real rectovaginal fistulae cases are extremely rare.)

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