Diarrhea (frequent or fluid bowel movements), occurs in about 5% of hospice patients.

Oral loperamide 2mg to 4mg every 6 hours acts locally on the gut and is usually more useful than the centrally acting opioids (morphine, codeine, diphenoxylate) because the patient is often already taking opioids. Loperamide should also be available if drugs that can cause diarrhea are prescribed.

The most common causes of diarrhea are:

  1. Fecal impaction

  2. Steatorrhea

  3. Malignant intestinal obstruction (dysfunction)

  4. Laxative imbalance or drugs

  5. Rectal tumor (discharge plus blood)

  6. Fecal incontinence

  7. Carcinoid tumor

1. Fecal impaction is commonly seen in patients on opioids who have been given laxatives either too late or in too low a dosage. It can often be diagnosed from the history. There are no bowel movements for several days, and then there is passage of small amounts of liquid feces, sometimes without control. Rectal examination reveals a large, clay-like lump of feces which usually has to be removed by manual evacuation under sedation. Occasionally the rectum is ballooned and empty, and the impaction has occurred higher up (palpable abdominally or visible on plain abdominal x-ray). The patient may require in-patient admission to clear this sort of constipation. (see Constipation)

2. Steatorrhea means loose, pale, foul-smelling feces. (Relatives sometimes fear they contain cancer.) Steatorrhea can be missed without a good history. The patient usually complains simply of diarrhea, but steatorrhea does not respond to anti-diarrheal drugs. It is due to malabsorption of fat, and is most commonly seen in patients with carcinoma of the pancreas. The patient usually has bowel movements four or five times a day, with large quantities of feces that tend to float, and are difficult to flush away in the toilet. Steatorrhea responds to pancreatic enzyme replacement tablets containing all major pancreatic enzymes: lipase, protease and amylase.

The enzymes are destroyed by gastric acid and therefore tablets are best taken immediately before a meal or a snack, or with milk. (The required dose may be 2 to 10 tablets or more, depending on the strength of the pancreatic replacement used.) The dosage is adjusted according to the frequency of bowel movements. Excessive dosage may irritate the skin around the anus. Resistant steatorrhea may further respond by giving cimetidine 200mg, 30 minutes before the meal, to reduce gastric acid secretion. Measurement of fecal fats by the laboratory is unnecessary: the clinical picture is usually obvious once considered.

3. Malignant intestinal obstruction is usually seen with carcinoma of the ovary (25% develop obstruction) or carcinoma of the colon or rectum. In reality, it is often malignant intestinal “dysfunction” rather than “obstruction” because bowel disturbances are often intermittent and can either cause constipation or diarrhea. (see Intestinal Obstruction)

Diarrhea in this situation is best treated with loperamide 2mg to 4mg every 6 hours (care being taken to stop it after the diarrhea has settled, to avoid constipation). Diarrhea due to malignant intestinal dysfunction can respond to high dose steroids (dexamethasone 8mg per day).

Occasionally a malignant ileo-colic fistula causes a short circuit of the bowel. Diarrhea can then be worsened by retrograde bacterial overgrowth in the small intestine (which is normally sterile) with deconjugation of bile salts and malabsorption of fat. This can respond to oral tetracycline 500mg every 6 hours.

4. Laxative imbalance – The incorrect use of laxatives can cause diarrhea. If the patient is on opioid analgesics it is essential to take laxatives daily. Usually there has been under-use of laxatives in a patient on opioids which has allowed constipation to develop. Excessive laxatives are then taken to clear the constipation and hard feces are finally passed, followed (sometimes explosively) by soft feces.

Other drugs that can cause diarrhea include antibiotics, antacids with magnesium salts, NSAIDs and antifibrinolytic drugs. Oral phosphate used to treat hypercalcemia causes severe diarrhea. Chemotherapy (especially with mitomycin or fluorouracil) can cause diarrhea.

5. Rectal tumor – Mucous discharge or bleeding from carcinoma of the rectum can be treated by radiotherapy. A palliative colostomy does not relieve these local symptoms. Hydrocortisone foam, one applicator-full 2 times a day, can be helpful, as can oral steroids (dexamethasone 8mg 2 times a day). Profuse mucous diarrhea can cause hypokalemia. Laser therapy via an endoscope can be very successful in reducing bleeding and discharge from carcinoma of the rectum, and it can also improve the patency of the lumen and prevent obstruction. It usually needs to be repeated. The discharge can be foul-smelling and metronidazole (500mg every 8 hours) usually reduces the smell. (see Lasers)

Bulk-forming drugs (methylcellulose tablets or granules) can help control diarrhea due to rectal tumors, by establishing a bowel routine. They take 2 or 3 days to take effect, and dose is tailored to effect.

6. Fecal incontinence due to loss of sphincter control – There may be perineal numbness, usually as part of spinal cord compression syndrome with paraplegia. It is usually best managed by reducing or stopping laxatives and giving daily or alternate-day manual evacuations. (see Spinal Cord Compression)

Fecal incontinence may be due to a recto-vaginal fistula, and the patient may be too embarrassed to complain that feces are leaking from her vagina. A palliative colostomy should always be considered for this distressing condition. (see Fistulas)

7. Carcinoid tumors are slow-growing tumors of the small intestine (less commonly bronchus, large bowel or pancreas) which can secrete 5HT (serotonin) causing:

  • Diarrhea

  • Wheeze

  • Flushing

These symptoms do not occur if blood from the tumor passes through a normal liver, so these tumors only produce symptoms once liver metastases have occurred. (Bronchial carcinoids are often metabolically inactive.) The primary tumor usually remains small but massive hepatomegaly eventually occurs. It is occasionally possible to block the metabolic effects with drugs, but treatment may fail because tumors can produce more than one active agent.

Diarrhea can be profuse (1 liter per day) and may not respond to anti-diarrheals. If the terminal ileum has been resected diarrhea may be due to excess bile salts, and cholestyramine can help. If it is due to 5HT, 5HT antagonists may help, either cyproheptadine 4mg to 8mg 4 times a day, or methysergide 1 mg at bedtime increasing to 1 mg to 2mg 3 times a day. Bulking of the feces (with methylcellulose) can reduce the frequency of diarrhea and establish a bowel routine.

The author and publisher have taken precautions to ensure that the information in this book is error-free. However, readers must be guided by their own personal and professional standards of good practice in evaluating and applying recommendations made herein. The contents of this book represent the views and experience of the author, and not necessarily those of the publisher.

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