A 42-year old woman complains of the intermittent passage of bright red blood per rectum for the last two weeks. There is no associated abdominal pain, nausea, or vomiting.
She underwent a subtotal colectomy with an ileostomy six months ago, due to fulminant attacks of ulcerative colitis that were refractory to medical treatment.
She also tested positive for human immunodeficiency virus (HIV) six years ago and has been on regular anti-retroviral therapy ever since. Her last CD4 count, performed two weeks ago, was within normal limits.
The remainder of the history is unremarkable. A complete blood count (CBC) shows no abnormalities.