Concepts in Surgery of the Anus, Rectum, and Pilonidal Region

Abstract

Successful management of anorectal disease depends on a clear understanding of what symptoms can be attributed to various conditions.1,2 In addition, consideration must be given to the impact of other aspects of colorectal physiology on function and healing. The perianal skin and lower aspect of the anal canal is richly innervated by sensory fibers. External hemorrhoids are venous plexuses located below the dentate line and covered with squamous epithelium. Internal hemorrhoids are submucosal vascular tissue containing blood vessels, smooth muscle, and connective tissue that are normally located above the dentate line. They are covered with transitional epithelium. Chronic straining is thought to cause excessive engorgement of the vascular cushions and disruption of the smooth muscle and connective tissue. This disruption allows the vascular cushions and the overlying muscosa to slide down the anal canal and prolapse during straining. Repetitive straining promotes further prolapse.