A fecal impaction is a large mass of dry, hard stool that can develop in the rectum due to chronic constipation. This mass may be so hard that it cannot come out of the body. Watery stool from higher in the bowel may move around the mass and leak out, causing soiling or diarrhea.
Impaction of the bowels
Causes, incidence, and risk factors
Certain people are at greater risk for developing chronic constipation, which can lead to fecal impaction.
Persons at risk for this condition include those who:
- Have limited ability to move such as bedridden patients, or persons with severe disease of the nervous system
- Take certain drugs, including:
- Anticholinergics, which affect the interaction between certain nerves and muscles
- Antidiarrhea medications
- Methadone maintenance treatment for drug addiction
- Narcotic pain medication
- Abdominal cramping
- Frequent straining with passage of liquid
- Rectal bleeding
- Small, semi-formed stools
- Sudden, watery diarrhea in someone who has chronic constipation
Signs and tests
The health care provider will examine your stomach area and rectum. The rectal exam will reveal a hard mass of dry stool in the rectum.
If there has been a recent change in your bowel habits, your doctor may recommend a colonoscopy to evaluate for colon or rectal cancer.
Treating a fecal impaction involves removing the impacted stool, and taking measures to prevent constipation and future fecal impactions.
Medications may be used to prevent another fecal impaction. Stool softeners such as docusate may be recommended to help pass soft, formed stools. Bulk fiber laxatives such as Metamucil may be used to add fluid and bulk to the stool.
Glycerin, bisacodyl suppositories, or other gentle laxatives may be used along with a bowel retraining program to establish a pattern of regular bowel movements. Food adjustments may be helpful in those with a limited diet.
Surgery is rarely needed to treat a fecal impaction. However, if the fecal impaction is not removed, the colon may become overly widened (megacolon) or the bowel can become completely blocked. Both of these conditions require emergency surgery to remove the impaction. Part of the injured bowel might have to be removed as well.
Dietary measures such as increasing fiber intake from whole-wheat grains, bran, and fresh fruits and vegetables may help add bulk to the stool and promote normal bowel movements. Make special efforts to increase daily fluid intake.
Regular exercise helps establish regular bowel movements. People who are confined to a wheelchair or bed should change position often and perform abdominal contraction exercises and leg raises. If possible, do these exercises several times a day. A physical therapist can recommend a program of exercises appropriate for your physical abilities.
The treatment of fecal impaction aims to remove the impaction and start a program to maintain normal bowel function. Often a warm mineral oil enema is used to soften and lubricate the fecal impaction. However, enemas alone are usually not enough to remove a large, hardened impaction.
The mass may have to be manually broken up. A health care provider will need to insert one or two fingers into the rectum and slowly break up the mass into smaller pieces so that it can be expelled.
Manual removal of a fecal impaction is usually performed in small steps to reduce the risk of injuring the rectal tissues. A series of suppositories may be given between manual removal attempts, to help clear the bowel.
With treatment, the outcome is good.
- Tear (ulceration) of the rectal tissue
- Tissue death (necrosis) or rectal tissue injury
Calling your health care provider
Tell your health care provider if you are experiencing chronic diarrhea or fecal incontinence after a long period of constipation. Also notify your health care provider if you are experiencing any of the following symptoms:
- Abdominal pain and bloating
- Blood in the stool
- Sudden constipation with abdominal cramps, and an inability to pass gas or stool. In this case, do not take any laxatives. Call your health care provider immediately.
- Very thin, pencil-like stools
Prevention of fecal impaction focuses on preventing constipation. Add fiber to the diet to promote normal stools. Also, get enough fluids and exercise to help in the formation of normal stool.
Always respond promptly when you have the urge to go to the bathroom (defecate).
Nelson H. Diseases of the rectum and anus. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 148.
David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; George F Longstreth, MD, Department of Gastroenterology, Kaiser Permanente Medical Care Program San Diego, California. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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