Hemorrhoids occur when the veins in the wall of the anus and rectum become swollen and stretched. Hemorrhoids that occur in the rectum are called internal hemorrhoids. They cannot usually be seen, but may droop down outside the anus. Those that form in the anus are called external hemorrhoids. They often appear as a small bulge under the skin.

Hemorrhoids are very common. They occur when an increase of pressure in the veins around the anus and rectum cause the veins to enlarge. This may occur due to many factors, including straining during a bowel movement, pregnancy and childbirth. Although hemorrhoids often cause bleeding, pain and a feeling of fullness in the rectum, they may not cause any problems in some people.

The diagnosis of hemorrhoids follows an evaluation of the patient’s medical history, including bowel habits and symptoms, and a physical examination by a gastroenterologist or other physician. A variety of tools (e.g., anoscope, sigmoidoscope) may be used to visually examine the anus and rectum.

Hemorrhoids that do not cause symptoms typically require no treatment. If symptoms are present, they often go away in a few days and can usually be treated with measures that patients can perform at home. These include eating more fiber, avoiding irritation to the area and soaking the anus in warm water. Surgery is very rarely needed for hemorrhoids, but may be performed to relieve excessive bleeding or pain. Most surgeries can be performed in a physician's office.