DEAR DOCTOR K:
I’m a healthy man in my 50s. I dread having a physical because of the digital rectal exam. What can the doctor even tell by doing this? Is it really necessary?
The digital rectal exam isn’t fun — I speak as both a doctor and patient. But it is a risk-free way to check for abnormalities of the anus, rectum and prostate gland.
Your rectum is the last few inches of your bowel, just above the anus. As you know, during the exam, your doctor inserts a gloved and lubricated finger into your rectum. You may lie on your side on an exam table with your knees pulled up toward your chest. If that position isn’t comfortable, you can have the exam performed while you stand, bent over the exam table.
As the doctor’s finger enters, you feel a pressure, but it is not painful unless you have an abnormality in the anus, such as an inflamed hemorrhoid. The exam takes about one to two minutes.
The exam allows your doctor to feel the wall of your rectum, checking for unusual lumps, swellings or tenderness. In men, the doctor will feel the prostate gland through the wall of the rectum. He or she will check for suspicious nodules, as well as for abnormalities in the gland’s size or shape. Here is an illustration of the procedure:
Doctors use the digital rectal exam both to evaluate symptoms and to screen for diseases even when you don’t have symptoms. The symptoms that prompt a rectal exam are those that affect the digestive system, genitals and urinary tract. For example, a doctor may do the exam to check the prostate in a man who complains of frequent urination.
The digital rectal exam is useful for both men and women. It screens for disease by identifying potentially cancerous masses in the rectum, prostate or female genital organs. Examination of the female organs also requires a second finger in the vagina and a hand gently pushing on the abdomen.
The other way the digital rectal exam screens for disease is to test a small stool sample for unsuspected blood. A person can have a small amount of bleeding in the digestive tract that doesn’t show up as visible blood in the bowel movement. Small amounts of bleeding are detected by chemical tests of the bowel movement.
Many different conditions in the digestive tract can cause bleeding. Some are very serious, such as cancer. Others are not serious, such as hemorrhoids. So finding signs of blood in the bowel movement doesn’t tell the doctor what’s wrong; it just signals that there’s a problem that needs to be diagnosed.
The digital rectal exam cannot feel most cancers of the intestine: They occur too far up in the large intestine for a finger to reach. Colonoscopy, sigmoidoscopy and barium enemas (performed less often these days) can see cancers that the finger cannot feel.