Diseases of the Rectum and Anus

Abstract

Anorectal disorders represent some of the most common, yet poorly understood conditions in primary care. Any discussion of these conditions requires a thorough understanding of the anorectal anatomy (Figs. 11.1 and 11.2). The anal canal spans 2 to 3 cm from the lower border of the anal crypts at the dentate line to the anal verge (external skin). 1 The anal canal is lined with a specialized squamous epithelium called anoderm. 1 Sensory innervation from the external skin extends upward to the dentate line. Most patients have no sensation above the dentate line and are exquisitely sensitive below it.Internal and external hemorrhoids are discussed here in detail, as patients often attribute all anorectal complaints to "hemorrhoids." Other conditions that are reviewed include anal fissures, abscesses, fistulas, incontinence, rectal prolapse, pruritus ani, infectious proctitis, hidradenitis suppurativa, condyloma acuminatum, and anal carcinoma.