Anus DiseasesAnus, Imperforate: A congenital abnormality characterized by the persistence of the anal membrane, resulting in a thin membrane covering the normal ANAL CANAL. Imperforation is not always complete and is treated by surgery in infancy. This defect is often associated with NEURAL TUBE DEFECTS; MENTAL RETARDATION; and DOWN SYNDROME.Anus Neoplasms: Tumors or cancer of the ANAL CANAL.Anal Canal: The terminal segment of the LARGE INTESTINE, beginning from the ampulla of the RECTUM and ending at the anus.Rectovaginal Fistula: An abnormal anatomical passage between the RECTUM and the VAGINA.Perineum: The body region lying between the genital area and the ANUS on the surface of the trunk, and to the shallow compartment lying deep to this area that is inferior to the PELVIC DIAPHRAGM. The surface area is between the VULVA and the anus in the female, and between the SCROTUM and the anus in the male.Rectal Fistula: An abnormal anatomical passage connecting the RECTUM to the outside, with an orifice at the site of drainage.Abortion, Eugenic: Abortion performed because of possible fetal defects.Urogenital Abnormalities: Congenital structural abnormalities of the UROGENITAL SYSTEM in either the male or the female.Rectum: The distal segment of the LARGE INTESTINE, between the SIGMOID COLON and the ANAL CANAL.Rectal Prolapse: Protrusion of the rectal mucous membrane through the anus. There are various degrees: incomplete with no displacement of the anal sphincter muscle; complete with displacement of the anal sphincter muscle; complete with no displacement of the anal sphincter muscle but with herniation of the bowel; and internal complete with rectosigmoid or upper rectum intussusception into the lower rectum.Abnormalities, MultipleCloaca: A dilated cavity extended caudally from the hindgut. In adult birds, reptiles, amphibians, and many fishes but few mammals, cloaca is a common chamber into which the digestive, urinary and reproductive tracts discharge their contents. In most mammals, cloaca gives rise to LARGE INTESTINE; URINARY BLADDER; and GENITALIA.Rectal Diseases: Pathological developments in the RECTUM region of the large intestine (INTESTINE, LARGE).Hemorrhoids: Swollen veins in the lower part of the RECTUM or ANUS. Hemorrhoids can be inside the anus (internal), under the skin around the anus (external), or protruding from inside to outside of the anus. People with hemorrhoids may or may not exhibit symptoms which include bleeding, itching, and pain.Propanidid: An intravenous anesthetic that has been used for rapid induction of anesthesia and for maintenance of anesthesia of short duration. (From Martindale, The Extra Pharmacopoeia, 30th ed, p918)Surgically-Created Structures: Organs or parts of organs surgically formed from nearby tissue to function as substitutes for diseased or surgically removed tissue.Dilatation: The act of dilating.Digestive System Abnormalities: Congenital structural abnormalities of the DIGESTIVE SYSTEM.Urinary Fistula: An abnormal passage in any part of the URINARY TRACT between itself or with other organs.Bladder Exstrophy: A birth defect in which the URINARY BLADDER is malformed and exposed, inside out, and protruded through the ABDOMINAL WALL. It is caused by closure defects involving the top front surface of the bladder, as well as the lower abdominal wall; SKIN; MUSCLES; and the pubic bone.Colostomy: The surgical construction of an opening between the colon and the surface of the body.