Rectal Bleeding After Radiation for Prostate Cancer

Last Modified: January 11, 2009

Dear OncoLink "Ask The Experts,"

I had seed implants for prostate cancer 2 years ago. I have had rectal bleeding ever since. Sometimes it is with a bowel movement and sometimes I'll feel it running down my legs. It is bright red and it's enough to come through my pants. I had a colonoscopy and it did not reveal the cause. Have you had any patients with this, and what kind of doctor should I see?

Richard Whittington, MD, Associate Professor of Radiation Oncology at the University of Pennsylvania School of Medicine, responds:

There are several possibilities for the cause of the bleeding. The most likely cause is that there is something occurring in the mid sigmoid colon or below. The three things that leap to mind are:

1. A diverticulum, which should cause diarrhea with the bleeding, but colonoscopy would be negative since the diverticulum only appears abnormal when it is actively bleeding. In between bleeding episodes, the “problem” diverticulum looks like any other diverticulum, and thus is missed. This condition is called diverticulosis with bleeding. This is different from a condition called diverticulitis, which does not bleed and is associated with pain and fever.

2. Radiation proctitis, which can occasionally be missed at colonoscopy unless they are careful to look at the distal 5cm of the rectum. This frequently requires putting the scope in and having it make a U-turn back on itself to look at the rectal ampulla. This condition may or may not be associated with pain or tenesmus (constant feeling of the need to empty the bowels), whereas proctitis from other causes usually is associated with tenesmus and can be exacerbated by a hard or large bowel movement.

3. Hemorrhoids, which may be the most likely cause because of the fact that the blood runs down the leg to soak the pants without any sensation of bowel motion. This suggests that the bleeding is coming from below the sphincter, and this is usually caused by a hemorrhoid. If it is bleeding this badly, that is an indication for ligation or sclerosis to manage the bleeding, which can be done by a colorectal surgeon.

As for which doctor to see, a colorectal surgeon is a good choice since they look at the lower rectum.