Prevalence of Constipation in Terminal Illness

Constipation is a decrease in the frequency of passage of well-formed stools and is characterized by stools that are hard and small and difficult to expel. It's a subjective condition, differing for individuals based upon their normal pattern of bowel movements and their symptoms of discomfort. It can be caused by anything that slows down the motility of the gut or obstructs the intestines.

Constipation occurs frequently in patients near the end of life. Cancer patients may have the highest prevalence, with as many as 70 percent to 100 percent of patients experiencing constipation at some point during their disease. This condition affects a patient's quality of life substantially. It causes physical, social, and psychological distress for patients, which can impact their caregivers as well.

The first sign of constipation is a decrease in the frequency and amount of bowel movements. Patients and their caregivers will sometimes attribute this decrease to a reduced intake of food or fluids. Because constipation is subjective, what it means for one patient may be different for another. For example, if a patient usually has a bowel movement every day and suddenly starts having them three times a week, constipation should be considered. If, however, a patient normally has a bowel movement every other day, going two or three days without one might not be a problem.

Other signs of constipation include bloating, abdominal distention, a change in the amount of gas passed, oozing liquid stool, rectal pain or pressure, rectal pain with bowel movements, and the inability to pass stool. If constipation has been untreated for some time, nausea and vomiting may also occur.

Constipation may be caused by the disease. Cancer-related constipation can be caused by tumors in or near digestive organs, the spine, or the pelvic region. The tumors may compress or obstruct the bowel or slow the motility of the intestines.

Neurological diseases, such as Parkinson's, MS, and ALS, sometimes interfere with gastric motility. Diabetes can cause neuropathy leading to decreased movement in the colon. Other conditions, such as hypothyroidism, can also cause constipation.

Lifestyle changes such as decreased appetite and fluid intake may lead to hypercalcemia, or an increase in calcium in the blood, which can, in turn, lead to decreased water absorption in the bowel, causing constipation. Weakness and decreased activity affect the ability to use abdominal wall muscles and to relax the pelvic floor muscles, which are essential for proper elimination.

Medications may also be to blame for constipation. Opioid analgesics, such as morphine and oxycodone, slow down the motility of the gut by suppressing forward peristalsis and increase the tone of the anal sphincter. Opioids also increase the absorption of water and electrolytes in the large and small intestine, leading to hard, dry stools.

Other medications that may contribute to constipation include:

• Vinka alkaloid chemotherapy such as Velban (vinblastine)
• Anticholinergic drugs like Phenergan (promethazine)
• Tricyclic antidepressants such as Paxil (paroxetine)
• Antiparkinsonian drugs including levodopa
• Iron supplements
• Antihypertensives (high blood pressure medication)
• Antihistamines like Benadryl (diphenhydramine)
• Antacids
• Diuretics including Lasix (furosemide)

Effective constipation prevention is based on adequate fluid intake, a proper diet, and physical activity (being active motivates the bowels).