While an anal abscess is an infection within one or more of the anal spaces, an anal fistula (Choice B) is a
tunneling between the anus or rectum and another epithelial lined space (eg, the skin overlying the drainage
site). Fifty percent of patients with anal abscesses will go on to develop a chronic fistula from the involved
anal gland to the overlying skin. Patients with fistulas typically present with an anal abscess that persists after
incision and drainage, or with a pustule-like lesion in the perianal or ischiorectal area that continually drains.
Surgical repair is usually necessary to eliminate the fistula while preserving fecal continence.