MedicineNet.com

About Us | Privacy Policy | Site Map
February 9, 2012

Hemorrhoids (cont.)

Medical Author:
Medical Editor:

What causes hemorrhoids?

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.


Patient Discussions

Viewers share their comments

Hemorrhoids - Symptoms Question: What symptoms and signs did you experience with hemorrhoids?
Hemorrhoids - Effective Treatments Question: What kinds of treatments have been effective for your hemorrhoids?

MedicineNet Doctors

Suggested Reading on Hemorrhoids by Our Doctors

  • Related Diseases & Conditions

    • Rectal Bleeding
      • Rectal bleeding (hematochezia) refers to the passage of bright red blood from the anus. Rectal bleeding may be moderate to severe and most bleeding comes from the colon, rectum, or anus. Common causes include anal fissures, hemorrhoids, diverticulitis, and more.
    • Diarrhea
      • Diarrhea is a change is the frequency and looseness of bowel movements. Cramping, abdominal pain, and the sensation of rectal urgency are all symptoms of diarrhea. Absorbents and anti-motility medications are used to treat diarrhea.
    • Pregnancy (Stages - Trimesters of Pregnancy)
      • There are many symptoms involved in the 1st, 2nd and 3rd trimesters of pregnancy. The first early pregnancy symptom is typically a missed period, but others include breast swelling and tenderness, nausea and sometimes vomiting, fatigue and bloating. Second trimester symptoms include backache, weight gain, itching, and possible stretch marks. Third trimester symptoms are additional weight gain, heartburn, hemorrhoids, swelling of the ankles, fingers, and face, breast tenderness, and trouble sleeping. Read more to learn about recommended procedures and tests for each stage of a healthy pregnancy.
    • Constipation
      • Constipation is defined medically as fewer than three stools per week and severe constipation as less than one stool per week. Constipation usually is caused by the slow movement of stool through the colon. There are many causes of constipation including medications, poor bowel habits, low fiber diets, abuse of laxatives, hormonal disorders, and diseases primarily of other parts of the body that also affect the colon.
    • Skin Tag
      • A skin tag is a small benign growth of skin that projects from the surrounding skin. Skin tags can vary in appearance (smooth, irregular, flesh colored, dark pigment, raised). Skin tags generally do not cause symptoms unless repeatedly irritated. Treatment for skin tag varies depending on the location on the body.
    • Anal Itching
      • Anal itching is the irritation of the skin at the exit of the rectum, known as the anus, accompanied by the desire to scratch. Causes include everything from irritating foods we eat, to certain disease and infections. Treatment options include local anesthetics, vasoconstrictors, protectants, astringents, antiseptics, keratolytics, analgesics, and corticosteroids. If condition persists, a doctor examination may be needed to identify an underlying cause.
    • Anal Fissure
      • An anal fissure is a small tear or cut in the skin lining of the anus. Pain and/or rectal bleeding during bowel movements are common symptoms of anal fissures. Treatment involves increasing liquid intake, using stool softeners and avoiding foods that may not be well-digested.
    • Laxatives for Constipation
      • Laxatives for treatment of constipation include over-the-counter preparations such as bulk-forming laxatives, stool softeners, lubricant laxatives, stimulant laxatives, saline laxatives, enemas and suppositories. Some over-the-counter laxatives are not recommended for patients with specific diseases or conditions. Some laxatives may have negative adverse effects if taken over long periods of time.
    • Portal Hypertension
      • Portal hypertension is most commonly caused by cirrhosis, a disease in which results from scarring of a liver injury. Other causes of portal hypertension include blood clots in the portal vein, blockages of the veins that carry the blood from teh liver to the heart, and a parasitic infection called schistosomiasis.
    • Pregnancy: Your Guide to Eating Right
    • Pregnancy Basics
      • Pregnancy can bring challenges like weight gain, stretch marks, varicose veins, heartburn, constipation, hemorrhoids, problems sleeping, and wondering if it is safe to have sex while pregnant. Learn how to manage and move through these challenges during pregnancy.
  • Medications

  • Procedures & Tests

  • Pictures, Images & Illustrations

  • Doctor's & Expert's Views

  • Health News

  • Health Features

Women's Health

Find out what women really need.



Symptom Checker: Your Guide to Symptoms & Signs: Pinpoint Your Pain









Use Pill Finder Find it Now

Pill Identifier on RxList

  • quick,
    easy,
    pill identification

Find a Local Pharmacy

  • including
    24 hour
    pharmacies