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 [a´nus] (pl. a´nus)
the opening of the rectum on the body surface.
 The anus. Left, Endoanal magnetic resonance image of the sphincter muscles. High-definition images can be obtained by using an endoanal MRI coil. Right, Explanatory diagram (coronal view in a normal patient). From Aspinall and Taylor Robinson, 2001.
imperforate anus congenital absence of the normal opening of the rectum. Called also anal atresia and atresia ani.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

a·nal a·tre·si·a

, atresia ani
congenital absence of an anal opening due to the persistence of epithelial plug (persistence of the anal membrane) or to complete absence of the anal canal.
Farlex Partner Medical Dictionary © Farlex 2012

a·nal a·tre·si·a

, atresia ani (ā'năl ă-trē'zē-ă, ă-trē'zē-ă' ā'nī)
Congenital absence of an anal opening due to the presence of a membranous septum (persistence of the cloacal membrane) or a complete absence of the anal canal.
Synonym(s): imperforate anus (1) , proctatresia.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012