What condition is associated with foul smelling anal discharge?

Fistula in ano is the condition associated with foul-smelling anal discharge because it involves an abnormal connection between the anal canal or rectum and the skin outside the anus. This abnormal passage can become infected, leading to the accumulation of pus and a discharge that can have a distinct, unpleasant odor.

In contrast, while anal abscesses can also lead to discharge, they typically present with pain, swelling, and often a more acute infection without the chronicity that characterizes a fistula in ano. Hemorrhoids primarily present with blood rather than a foul-smelling discharge, and anal fissures usually cause pain and bleeding during bowel movements but do not typically result in such discharge. Therefore, the characteristics of a fistula in ano make it the most fitting choice regarding foul-smelling anal discharge.