Constipation is one of the most frequent gastrointestinal complaints in the USA and Western countries. There are at least 2.5 million doctor visits for constipation in the USA each year, and hundreds of millions of dollars are spent on laxatives yearly.
- How is constipation defined?
Constipation is often thought of as a decrease in the number of bowel movements/day, and many people think that they need to have a bowel movement every day. But this is not correct. If you have three bowel movements each week, and feel well, you are healthy. Constipation also means too much straining with bowel movements, or passage of small hard stools or a sense that they have not completely emptied their bowels. The American College of Gastroenterology defines constipation based upon symptoms including unsatisfactory defecation with either infrequent stools, difficulty in passing stool or both. But if there is a new change in bowel habits, people should consult with their doctor.
- What causes constipation?
Constipation most commonly occurs when the stool (waste formed after eating and digestion) moves slowly through the digestive tract. Less water consumption, changes in diet, decrease in activity, and certain medicines may cause this to happen. When stool moves slowly, too much water is absorbed from the stool, and it becomes hard and dry. Another cause, bowel obstruction (blockage), is serious but uncommon.
- What kind of evaluation should constipated patients undergo?
A doctor usually depends on the patients’ history while making a diagnosis. The doctor also examines the rectum with a gloved finger and, if stool is present, determines the amount and consistency. The stool is tested for occult (hidden) blood. A good history and physical examination is all that is needed to confirm a diagnosis of constipation and to determine the likely cause.
When the cause remains unclear, tests may be done. The doctor may advise an examination with a flexible viewing tube, either of just the lower part of the large intestine (sigmoidoscopy) or of the entire large intestine (colonoscopy). This examination is important if the constipation developed suddenly or if there is hidden blood in the stool.
Occasionally, other tests are needed to determine the cause. An abdominal x-ray may show evidence of bowel obstruction or suggest another cause. Other tests measure transit through the colon over several days by swallowing capsules containing tiny rings that can be seen on x-rays or by swallowing a telemetry capsule. Rectal sensation and muscle coordination can be assessed by placing a thin catheter into the rectum (anorectal manometry). Finally, emptying of the rectum can be tested in the laboratory or with special x-rays (defecography)..
- What are the treatments for constipation?
When stool is hard, tap water enemas are used. The patient is asked to lay on their left side, with knees flexed. About 5 to 10 ounces of water, at body temperature, is gently introduced into the rectum and sigmoid colon. The hard stool gets softened and comes out with the water. Non-prescription prepackaged enemas can be used in place of tap water. If enemas fail to work, a health care worker may need to remove the stool manually using a gloved finger. The person is then sometimes asked to drink a solution containing dissolved salts and polyethylene glycol, which cleanses the digestive tract.
After the hard stool has been removed, the patient is told to add fiber to the diet or to use laxatives to prevent constipation. Laxatives may be used every two to three days or even regularly.
If the stool is not impacted, there are several ways of treating constipation. Increasing the intake of water and fiber is often the first step. Vegetables, fruit (especially prunes), whole-grain breads, and high-fiber cereals are excellent sources of fiber. Bran is an alternative source, although it may cause excessive gas and bloating. To prevent gas, fiber should be eaten with plenty of fluids.
Laxatives and stool softeners are sometimes needed if changes in diet are insufficient. Most laxatives are safe for long-term uses, if used appropriately.
Bulking agents, such as psyllium and methylcellulose, are laxatives that help hold water in the stool and add bulk to it. The increased bulk causes movements of the large intestines, making the stool easy to pass. Bulkier stools are softer and easier to pass. Bulking agents act slowly and gently. These agents generally are taken in small amounts at first. The dose is increased gradually until the patient’s bowel movements become regular.
Osmotic agents are laxatives that keep large amounts of water in the large intestine, making the stool soft and loose. These laxatives consist of salts or sugars that are poorly absorbed. Some contain magnesium and phosphate, which can be partially absorbed resulting in harm to people with kidney failure.
Stimulant laxatives contain substances that directly stimulate the walls of the large intestine (such as senna and bisacodyl), causing them to contract. Taken by mouth, stimulant laxatives generally cause a bowel movement in six to eight hours. Some are available as suppositories. When taken as suppositories, these laxatives often work in 15 to 60 minutes. Stimulant laxatives are best used for brief periods. If longer use is needed, they may be used daily or every other day, and optimally under a doctor's supervision.
Newer medications, which increase secretion of fluids into the intestine, are available only by prescription. They should be considered if constipation does not respond well to over-the-counter laxatives. When constipation is due to opiate drugs used to treat severe pain, new agents that block the effects of opiates on the gut sometimes can help. Occasionally, a problem with coordination of pelvic floor and anorectal muscles may be identified. This can be treated with biofeedback or muscle retraining exercises; such treatments are performed only in centers which specialize in this area and upon referral by a doctor.
- Can constipation be prevented?
A combination of an adequate intake of fluids, adequate exercise, and a high-fiber diet may prevent constipation. Laxatives are sometimes a helpful addition to these measures. For example, when a person needs to take a potentially constipating drug, a stimulant laxative along with increased intake of dietary fiber and fluids helps prevent constipation.
Author(s) and Publication Date(s)
Cuckoo Choudhary, Thomas Jefferson University, Philadelphia, PA – Updated August 2022.
Arnold Wald, MD, MACG, University of Wisconsin School of Medicine and Public Health, Madison, WI – Published June 2004. Updated January 2010. Updated March 2016.