Constipation is a decrease in the frequency of bowel movements or difficulty in the formation or passing of stool, the body's solid waste.
What feels like constipation to one person may be normal for another.
The colon (large intestine) controls the formation and passage of stool from the body. The colon absorbs water out of the solid waste and moves the waste to the rectum and anus. Anything that changes the colon's ability to regulate the amount of water in stool or that affects the muscles and nerves of the colon that are responsible for moving waste toward the rectum and anus can lead to constipation.
Common Causes of Constipation
The three most common underlying causes of constipation are:
- Too much water is absorbed from the waste as it passes through the colon, resulting in hard, dry stools.
- There are changes in the colon's ability to coordinate the muscle contractions needed to pass the stool to the rectum and anus, causing stool to become "stuck."
- The colon is blocked by something, such as a tumor.
There are a variety of reasons why one of these three things can occur and lead to constipation. Common causes of occasional, "garden-variety" constipation that many people experience from time to time, include:
- Not eating enough dietary fiber
- Not drinking enough water and other liquids
- Lack of exercise
- Ignoring the urge to defecate until a more convenient time
- Stopping a laxative after using one frequently
- Using certain medications, particularly some chemotherapy drugs and those used for pain (opiates), nausea and depression
Constipation As a Symptom of Cancer
When stool enters the colon, it is a thick liquid that can flow around partial blockages or through narrow areas. As it progresses through the colon and more water is removed, it becomes thicker. This inhibits its ability to get around blockages and narrow areas. A tumor in the middle to lower portions of the colon, or in the rectum, can make it difficult for stool to pass by, leading to constipation.
If you suffer from chronic or intermittent constipation, the sooner you get a diagnosis the better. With colon cancer, for example, if it is diagnosed in the earliest stages, survival rates are well over 90%. If the cancer is more advanced, and has spread beyond the colon, survival rates drop dramatically.
If you notice changes in your bowel habits, talk to your doctor. In many cases, you will find out that you do not have colon cancer and that something less serious is causing your constipation. But it is better to err on the side of caution and get it checked out.
Finding the Cause of Your Symptoms
A screening exam, such as a colonoscopy or flexible sigmoidoscopy, may be scheduled to help your doctor find the cause of your symptoms. If you are nervous about getting screened, you can educate yourself so you know what to expect and don't have to dread your screening test.
See Your Doctor If...
- Three or more days have passed since your last bowel movement; two days if you have used a laxative
- You see blood in or on your stool
- You have persistent cramps or severe abdominal or rectal pain
- You are vomiting in association with severe constipation
- You are frequently or regularly constipated
American Cancer Society. Do I Have Colon Cancer? Accessed July 20, 2009. http://www.cancer.org/docroot/CRI/content/CRI_2_8_Do_I_Have_Colon_and_Rectum_Cancer.asp