Many gastrointestinal problems may involve the anus and rectum. The rectum is the end of the large intestine, between the sigmoid colon and the anus. The anus is located at the very end of the digestive tract, where stool exits the body. The anal sphincters are the rings of muscle that keep the anus closed between bowel movements. Changes in the frequency, consistency, composition or volume of bowel movements may signify a gastrointestinal problem.

Many anal and rectal problems involve abnormal structures and can be identified by a visual or manual examination. These include hemorrhoids, obstruction and congenital problems where there is no anal opening (imperforate anus) or the anal opening is abnormally small. Some problems occur due to malfunctioning muscles, nerves or other structures in the anus or rectum. Problems related to the function of the anus and rectum include fecal incontinence, proctalgia fugax or rectal pain, and painful bowel movements (dyschezia). Anal and rectal problems may also result from infectious or inflammatory causes such as anorectal abscesses and proctitis.

While the causes of anal and rectal problems are quite diverse, these problems may produce very similar symptoms. The most common of these are anal itching, constipation, pain and bleeding. The diagnosis of anal and rectal problems typically involves an evaluation of the patient's medical history, a physical examination and a series of diagnostic tests. While gathering the patient’s medical history, physicians and gastroenterologists generally ask about symptoms, bowel habits and changes in bowel patterns. The physical examination usually involves the examination of the anal area and a digital rectal exam. The most common diagnostic tests include anoscopy and sigmoidoscopy.