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Gastrointestinal Complications (Patient)

General Information

The gastrointestinal (GI) tract is part of the digestive system, which processes nutrients (vitamins, minerals, carbohydrates, fats, proteins, and water) in foods that are eaten and helps pass waste material out of the body. The GI tract includes the stomach and intestines (bowels). The stomach is a J-shaped organ in the upper abdomen. Food moves from the throat to the stomach through a hollow, muscular tube called the esophagus. After leaving the stomach, partly-digested food passes into the small intestine and then into the large intestine (colon). The last 6 inches of the large intestine are the rectum and the anal canal. The anal canal ends at the anus (the opening of the large intestine to the outside of the body).
Gastrointestinal (digestive) system anatomy; shows esophagus, liver, stomach, colon, small intestine, rectum, and anus.
Anatomy of the lower digestive system, showing the colon and other organs.

GI complications are common in cancer patients. Complications are medical problems that occur during a disease, or after a procedure or treatment. They may be caused by the disease, procedure, or treatment, or may have other causes. This summary describes the following GI complications and their causes and treatments:

  • Constipation.
  • Fecal impaction.
  • Bowel obstruction.
  • Diarrhea.
  • Radiation enteritis.

This summary is about GI complications in adults with cancer. Treatment of GI complications in children is different than treatment for adults.


With constipation, bowel movements are difficult or don't happen as often as usual.

Constipation is the slow movement of stool through the large intestine. The longer it takes for the stool to move through the large intestine, the more it loses fluid and the drier and harder it becomes. The patient may be unable to have a bowel movement, have to push harder to have a bowel movement, or have fewer than their usual number of bowel movements.

Certain medicines, changes in diet, not drinking enough fluids, and being less active are common causes of constipation.

Constipation is a common problem for cancer patients. Cancer patients may become constipated by any of the usual factors that cause constipation in healthy people. These include older age, changes in diet and fluid intake, and not getting enough exercise. In addition to these common causes of constipation, there are other causes in cancer patients.

Other causes of constipation include:

  • Opioids and other pain medicines. This is one of the main causes of constipation in cancer patients.
  • Chemotherapy.
  • Medicines for anxiety and depression.
  • Antacids.
  • Diuretics (drugs that increase the amount of urine made by the body).
  • Supplements such as iron and calcium.
  • Sleep medicines.
  • Drugs used for anesthesia (to cause loss of feeling for surgery or other procedures).
  • Not drinking enough water or other fluids. This is a common problem for cancer patients.
  • Not eating enough food, especially high-fiber food.
Bowel movement habits
  • Not going to the bathroom when the need for a bowel movement is felt.
  • Using laxatives and/or enemas too often.
Conditions that prevent activity and exercise
  • Spinal cord injury or pressure on the spinal cord from a tumor or other cause.
  • Broken bones.
  • Fatigue.
  • Weakness.
  • Long periods of bed rest or not being active.
  • Heart problems.
  • Breathing problems.
  • Anxiety.
  • Depression.
Intestinal disorders
  • Irritable colon.
  • Diverticulitis (inflammation of small pouches in the colon called diverticula).
  • Tumor in the intestine.
Muscle and nerve disorders
  • Brain tumors.
  • Spinal cord injury or pressure on the spinal cord from a tumor or other cause.
  • Paralysis (loss of ability to move) of both legs.
  • Stroke or other disorders that cause paralysis of part of the body.
  • Peripheral neuropathy (pain, numbness, tingling) of feet.
  • Weakness of the diaphragm (the breathing muscle below the lungs) or abdominal muscles. This makes it hard to push to have a bowel movement.
Changes in body metabolism
  • Having a low level of thyroid hormone, potassium, or sodium in the blood.
  • Having too much nitrogen or calcium in the blood.
  • Having to go farther to get to a bathroom.
  • Needing help to go to the bathroom.
  • Being in unfamiliar places.
  • Having little or no privacy.
  • Feeling rushed.
  • Living in extreme heat that causes dehydration.
  • Needing to use a bedpan or bedside commode.
Narrow colon
  • Scars from radiation therapy or surgery.
  • Pressure from a growing tumor.

An assessment is done to help plan treatment.

The assessment includes a physical exam and questions about the patient's usual bowel movements and how they have changed.

The following tests and procedures may be done to help find the cause of the constipation:

  • Physical exam: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. The doctor will check for bowel sounds and swollen, painful abdomen.
  • Digital rectal exam (DRE): An exam of the rectum. The doctor or nurse inserts a lubricated, gloved finger into the lower part of the rectum to feel for lumps or anything else that seems unusual. In women, the vagina may also be examined.
  • Fecal occult blood test: A test to check stool for blood that can only be seen with a microscope. Small samples of stool are placed on special cards and returned to the doctor or laboratory for testing.
    Fecal Occult Blood Test (FOBT) kit; shows card, applicator, and return envelope.
    Fecal Occult Blood Test (FOBT) kit to check for blood in stool.
  • Proctoscopy: An exam of the rectum using a proctoscope, inserted into the rectum. A proctoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove tissue to be checked under a microscope for signs of disease.
  • Colonoscopy: A procedure to look inside the rectum and colon for polyps, abnormal areas, or cancer. A colonoscope is inserted through the rectum into the colon. A colonoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove polyps or tissue samples, which are checked under a microscope for signs of cancer.
    Colonoscopy; shows colonoscope inserted through the anus and rectum and into the colon. Inset shows patient on table having a colonoscopy.
  • Abdominal x-ray: An x-ray of the organs inside the abdomen. An x-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body.

There is no "normal" number of bowel movements for a cancer patient. Each person is different. You will be asked about bowel routines, food, and medicines:

  • How often do you have a bowel movement? When and how much?
  • When was your last bowel movement? What was it like (how much, hard or soft, color)?
  • Was there any blood in your stool?
  • Has your stomach hurt or have you had any cramps, nausea, vomiting, gas, or feeling of fullness near the rectum?
  • Do you use laxatives or enemas regularly?
  • What do you usually do to relieve constipation? Does this usually work?
  • What kind of food do you eat?
  • How much and what type of fluids do you drink each day?
  • What medicines are you taking? How much and how often?
  • Is this constipation a recent change in your normal habits?
  • How many times a day do you pass gas?

For patients who have colostomies, care of the colostomy will be discussed.

Treating constipation is important to make the patient comfortable and to prevent more serious problems.

It's easier to prevent constipation than to relieve it. The health care team will work with the patient to prevent constipation. Patients who take opioids may need to start taking laxatives right away to prevent constipation.

Constipation can be very uncomfortable and cause distress. If left untreated, constipation may lead to fecal impaction. This is a serious condition in which stool will not pass out of the colon or rectum. It's important to treat constipation to prevent fecal impaction.

Prevention and treatment are not the same for every patient. Do the following to prevent and treat constipation:

  • Keep a record of all bowel movements.
  • Drink eight 8-ounce glasses of fluid each day. Patients who have certain conditions, such as kidney or heart disease, may need to drink less.
  • Get regular exercise. Patients who cannot walk may do abdominal exercises in bed or move from the bed to a chair.
  • Increase the amount of fiber in the diet by eating more of the following:
    • Fruits, such as raisins, prunes, peaches, and apples.
    • Vegetables, such as squash, broccoli, carrots, and celery.
    • Whole grain cereals, whole grain breads, and bran.
    It's important to drink more fluids when eating more high-fiber foods, to avoid making constipation worse. (See the Constipation section of the PDQ summary on Nutrition in Cancer Care for more information.) Patients who have had a small or large intestinal obstruction or have had intestinal surgery (for example, a colostomy) should not eat a high-fiber diet.
  • Drink a warm or hot drink about one half-hour before the usual time for a bowel movement.
  • Find privacy and quiet when it is time for a bowel movement.
  • Use the toilet or a bedside commode instead of a bedpan.
  • Take only medicines that are prescribed by the doctor. Medicines for constipation may include bulking agents, laxatives, stool softeners, and drugs that cause the intestine to empty.
  • Use suppositories or enemas only if ordered by the doctor. In some cancer patients, these treatments may lead to bleeding, infection, or other harmful side effects.

When constipation is caused by opioids, treatment may be drugs that stop the effects of the opioids or other medicines, stool softeners, enemas, and/or manual removal of stool.

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