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Anorectal malformation

DA: 245

Developmental anomaly information

Definition: Anorectal malformations are a group of malformations that involve the distal anus and rectum as well as the urinary and genital tracts. Defects range from mild anal anomalies to complex cloacal malformations. Most anorectal malformations result from abnormal development of the urorectal septum, resulting in incomplete separation of the cloaca into urogenital and anorectal portions. A-The following are low malformations of the anorectal region: 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. B-The following are high malformations of the anorectal region: 1-Anorectal Agenesis, with or without fistula--The rectum ends well above the anal canal; this is the most common type of anorectal malformation. Although the rectum may end blindly, there is usually a fistula to the urethra in males or the vagina in females. Anorectal agenesis with a fistula results from incomplete separation of the cloaca by the urorectal septum. 2-Rectal Atresia---The anal canal and the rectum are present, but they are separated by an atretic segment of rectum. The cause of rectal atresia may be abnormal recanalization or defective blood supply, as discussed with atresia of the small intestine.

Developmental anomaly parent: (empty)

Topology: (empty)

System: (empty)

Developmental anomaly category: (empty)

Case records

Humpath: 4164

OMIM: 107100

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

Last modified: 2009-01-05 17:00:13 by farideh

Created: 2008-06-04 02:32:12 by jcfournet

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