(proctatresia) partial or complete obstruction of the anus: a congenital malformation in which the anal canal fails to develop correctly and the rectum ends blindly above the muscles of the perineum. Many types exist, including developmental anal stenosis, persistent anal membrane, and covered anus (due to fused genital folds). Most mild cases of imperforate anus can be treated by a simple operation. If the defect is extensive a temporary opening is made in the colon (see colostomy), with later surgical reconstruction of the rectum and anus.... imperforate anus
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