What causes hemorrhoids?

Hemorrhoids are swollen veins in the anal canal. This common problem can be painful, but it's usually not serious.

Veins can swell inside the anal canal to form internal hemorrhoids. Or they can swell near the opening of the anusto form external hemorrhoids. You can have both types at the same time. The symptoms and treatment depend on which type you have.

Many people have hemorrhoids  at some time.

Too much pressure on the veins in the pelvic and rectal area causes hemorrhoids.

Normally, tissue inside the anus fills with blood to help control bowel movements. If you strain or sit on the toilet a long time to move stool, the increased pressure causes the veins in this tissue to swell and stretch. This can cause hemorrhoids.

Diarrhea or constipation also may lead to straining and can increase pressure on veins in the anal canal.

Pregnant women can get hemorrhoids during the last 6 months of pregnancy. This is because of increased pressure on the blood vessels in the pelvic area. Straining to push the baby out during labor can make hemorrhoids worse.

Being overweight can also lead to hemorrhoids.

The most common symptoms of both internal and external hemorrhoids include:

• Bleeding during bowel movements. You might see streaks of bright red blood on toilet paper after you strain to have a bowel movement.
• Itching.
• Rectal pain. It may be painful to clean the anal area.

With internal hemorrhoids, you may see bright red streaks of blood on toilet paper or bright red blood in the toilet bowl after you have a normal bowel movement. You may see blood on the surface of the stool.

Internal hemorrhoids often are small, swollen veins in the wall of the anal canal. But they can be large, sagging veins that bulge out of the anus all the time. They can be painful if they bulge out and are squeezed by the anal muscles. They may be very painful if the blood supply to the hemorrhoid is cut off. If hemorrhoids bulge out, you also may see mucus on the toilet paper or stool.

External hemorrhoids can get irritated and clot under the skin, causing a hard painful lump. This is called a thrombosed, or clotted, hemorrhoid.

Your doctor can tell if you have hemorrhoids by asking about your past health and doing a physical exam.

You may not need many tests at first, especially if you are younger than 50 and your doctor thinks that your rectal bleeding is caused by hemorrhoids. Your doctor may just examine your rectum  with a gloved finger. Or your doctor may use a short, lighted scope to look inside the rectum.

Rectal bleeding can be a sign of a more serious problem, such as colon, rectal, oranal cancer. So if the first exam does not show a clear cause of your problems, your doctor may use a lighted scope (sigmoidoscope) to look at the lower third of your colon. Or your doctor may use another kind of scope (colonoscope) to look at the entire colon to check for other causes of bleeding.