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Imperforate Anus

DA: 100

Developmental anomaly information

Definition: Imperforate Anus : Some form of imperforate anus occurs once in about 5000 births; it is more common in males. It results from low malformations of the anorectal region and classified as: 1-Anal Agenesis, with or without fistula—The anal canal may end blindly and there may be an ectopic opening (ectopic anus), or fistula, that commonly opens into the perineum. However, the fistula may open into the vulva in females or the urethra in males. Anal agenesis with fistula results from incomplete separation of the cloaca by the urorectal septum. It accounts for about 46 percent of cases. 2- Anal Stenosis--The anus is in the normal position, but there is a narrowing of the anal canal. This malformation is probably caused by a slight dorsal deviation of the urorectal septum as it grows caudally to fuse with the cloacal membrane. As a result, the anal membrane (and later the anus) is small. Sometimes, only a small probe can be inserted (the so-called microscopic anus). 3-Membranous Atresia (“Covered Anus”)--The anus is in the normal position, but a thin layer of tissue separates the anal canal from the exterior. The membrane is thin enough to bulge on straining and appears blue from the presence of meconium behind it. This malformation is very rare and results from failure of the anal membrane to perforate at the end of the eighth week.


  • Membranous Atresia (“Covered Anus”)
  • Anorectal Agenesis, with or without fistula
  • Rectal Atresia

Developmental anomaly parent: Anorectal malformation

Topology: Human body > Pelvis > Rectum

System: Human body > Digestive system > Anus

Developmental anomaly category: Malformation

Case records MDB1, MDB409, MDB115, MDB137, MDB141, MDB179, MDB208, MDB209, MDB246, MDB255, MDB262, MDB306, MDB325, MDB382, MDB402, MDB439, MDB462, MDB481, MDB492, MDB521, MDB150, MDB222

Humpath: 4134

Observed in MDB cases
Observed in combinaisons (MDB)
Observed in malformative diseases (MDB)
Associated genes in profile
Associated genes in malformative diseases
Associated chromosomal diseases
Associated signaling pathways
Associated developmental anomalies

Here is the list of developmental anomalies associated with this developmental anomaly, based on the cases' information :

Last modified: 2009-01-05 17:05:54 by farideh

Created: 2008-03-07 01:00:00 by phsaw

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