Introduction An anal fistula is an abnormal communication between the inside of the anus and epithelium outside the anus. The most common anal fistula is an anocutaneous fistula, which is the subject of this chapter. Etiology Anal glands have an…
Abscesses in the anorectal region occur in all age groups and are a common, distressing problem. Predisposing factors include diabetes, Crohn disease, previous perianal surgery, and impairment of immunity, including human immunodeficiency virus (HIV); however, most abscesses occur spontaneously in…
Introduction An anal fissure is a linear tear in the lining of the anal canal that usually becomes symptomatic because it exposes the internal anal sphincter and causes painful spasms in that muscle. An anal fissure is a common condition…
Hemorrhoids are vascular cushions that lie close to the anus and are subject to the stresses and strains of defecation. They are normal structures that become symptomatic when thrombosis or prolapse develops as a result of either a congenital weakness…
Anatomy of the Colon and Rectum Colon The colon can be divided embryologically into the midgut (the transverse colon and portions proximal to it) and the hindgut (the distal half of the colon). The length of the colon is approximately…