What causes and how to diagnose hemorrhoids?

By age 50, about half the population has experienced one or more of the classic symptoms, which include rectal pain, itching, bleeding, and possibly prolapse (hemorrhoids that protrude through the anal canal). Although hemorrhoids are rarely dangerous, they can be a recurrent and painful intrusion. Fortunately, there’s a lot we can do about them.

What causes hemorrhoids?

Experts are divided on exactly what causes hemorrhoids, but probably several mechanisms are at work. Traditionally, hemorrhoids are associated with chronic constipation, straining during bowel movements, and prolonged sitting on the toilet — all of which interfere with blood flow to and from the area, causing it to pool and enlarge the vessels. This also explains why hemorrhoids are common during pregnancy, when the enlarging uterus presses on the veins.

More recent studies show that patients with hemorrhoids tend to have a higher resting anal canal tone — that is, the smooth muscle of the anal canal tends to be tighter than average (even when not straining). Constipation adds to these troubles, because straining during a bowel movement increases pressure in the anal canal and pushes the hemorrhoids against the sphincter muscle. Finally, the connective tissues that support and hold hemorrhoids in place can weaken with age, causing hemorrhoids to bulge and prolapse.
 

Diagnosing hemorrhoids

Hemorrhoids can usually be diagnosed from a simple medical history and physical exam. External hemorrhoids are generally apparent, especially if a blood clot has formed. Your clinician may perform a digital rectal exam to check for blood in the stool. She or he may also examine the anal canal with an anoscope, a short plastic tube inserted into the rectum with illumination. If there’s evidence of rectal bleeding or microscopic blood in the stool, flexible sigmoidoscopy or colonoscopy may be performed to rule out other causes of bleeding, such as colorectal polyps or cancer, especially in women over age 50.