1. Hemorrhoids Slideshow Pictures
2. Take the Hemorrhoids Quiz!
3. Inflammatory Bowel Disease (IBD) Slideshow

Medical Author:

Thomas P. Sokol, MD, FACS, FASCRS

Thomas P. Sokol, MD, FACS, FASCRS

Thomas P. Sokol, MD received his medical degree from the University of Health Sciences/The Chicago Medical School in 1980. He went on to his general surgical residency at Harbor/UCLA Medical Center and then to the Carle Clinic/ University of Illinois for Fellowship Training in Colon and Rectal Surgery.

View Full Profile

Medical Editor:

Jay W. Marks, MD

Jay W. Marks, MD

Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

View Full Profile

In this Article

• Hemorrhoid facts
• What are hemorrhoids?
• What causes hemorrhoids?
• What are the symptoms of hemorrhoids?
• How are hemorrhoids diagnosed?
• What is the treatment for hemorrhoids?
• Diet
• Over-the-counter medications for hemorrhoids
• Nonoperative procedures for internal hemorrhoids
• Surgery
• Pictures of Hemorrhoids - Slideshow
• Take the Hemorrhoids Quiz!
• Pictures of Inflammatory Bowel Disease (IBD) - Slideshow
• Hemorrhoids (Piles) FAQs
• Patient Comments: Hemorrhoids - Effective Treatments
• Patient Comments: Hemorrhoids - Causes
• Patient Comments: Hemorrhoids - Symptoms
• Find a local Gastroenterologist in your town
• Hemorrhoids Index

It is not known why hemorrhoids enlarge. There are several theories about the cause, including inadequate intake of fiber, prolonged sitting on the toilet, and chronic straining to have a bowel movement (constipation). None of these theories has strong experimental support. Pregnancy is a clear cause of enlarged hemorrhoids though, again, the reason is not clear. Tumors in the pelvis also cause enlargement of hemorrhoids by pressing on veins draining upwards from the anal canal.

One theory proposes that it is the shearing (pulling) force of stool, particularly hard stool, passing through the anal canal that drags the hemorrhoidal cushions downward. Another theory suggests that with age or an aggravating condition, the supporting tissue that is responsible for anchoring the hemorrhoids to the underlying muscle of the anal canal deteriorates. With time, the hemorrhoidal tissue loses its mooring and slides down into the anal canal.

One physiological fact that is known about enlarged hemorrhoids that may be relevant to understanding why they form is that the pressure is elevated in the anal sphincter, the muscle that surrounds the anal canal and the hemorrhoids. The anal sphincter is the muscle that allows us to control our bowel movements. It is not known, however, if this elevated pressure precedes the development of enlarged hemorrhoids or is the result of the hemorrhoids. Perhaps during bowel movements, increased force is required to force stool through the tighter sphincter. The increased shearing force applied to the hemorrhoids by the passing stool may drag the hemorrhoids downward and enlarge them.