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Anus and perianal area


Congenital defects

Reviewer: Nat Pernick, M.D. (see Reviewers page)
Revised: 13 April 2013, last major update April 2005
Copyright: (c) 2003-2013, PathologyOutlines.com, Inc.


● Occur in one per 5,000 births

High (supralevator) anomalies (40%):
● Also called anorectal agenesis
● No anal canal, rectum ends above levator ani muscle
● Causes severe obstruction
● Associated with anomalies in vertebrae and urinary tract, defective innervation of pelvic muscles, fistulas from rectum to bladder, urethra or vagina
● Complicated surgery is needed for reconstruction

Low (translevator) anomalies (40%):
● Includes ectopic (perineal, vestibular or vulvar) anus, anal stenosis and covered (imperforate) anus (failure of cloacal diaphragm to rupture)
● Simple surgery is curative
● No severe obstruction, no/rare associated anomalies, normal pelvic innervation

Intermediate anomalies (15%):
● Includes anal agenesis (may be associated with Larsenís syndrome, Hum Pathol 1991;22:1055), anorectal stenoses, anorectal membrane
● Need complicated surgery

Other (5%):
● Perineal groove, persistent anal membrane
● Also persistence of cloaca (bladder, genital tract and bowel empty into single narrow channel that opens onto perineum with small orifice)
● Exstrophy of cloacal membrane (Arch Pathol Lab Med 1987;111:157)

End of Anus and perianal area > General > Congenital defects

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