Constipation
W. Robert Kiser
Approach
Constipation, defined as the passage of two or fewer stools per week (1), is the most frequently reported gastrointestinal (GI) complaint in primary care, responsible for as many as 1.25 million patient visits annually (2).
A. The potential causes are legion, but can be generally classified by the acrostic MADE-O-FUN:
1. M: medications (anticholinergics, antispasmotics, antacids containing aluminum or calcium, diuretics, clonidine, calcium channel blockers, overuse of laxatives, narcotics, and others)
2. A: activity—general inactivity or debility
3. D: dietary—inadequate fluid and food intake
4. E: electrolytes and endocrine—hypokalemia, hypercalcemia, hypothyroidism, uremia, diabetes mellitus
5. O: obstruction—tumor, stricture, rectocoele, foreign body
6. F: functional—depression or irritable bowel syndrome
7. U: unusual things—thankfully, rare!
8. N: neurologic disorders—parkinsonism, multiple sclerosis, autonomic insufficiency associated with diabetes mellitus
History
The assessment and evaluation of the constipated patient begins with the history.
A. What is the patient’s description of the onset, duration, and frequency of constipation? Constipation of recent onset is suggestive of tumor.
B. Is rectal bleeding, melena, or narrowing of the stool caliber (all suggesting neoplasia) present (Chapter 9.11)?
C. What over-the-counter (OTC) medications are being used? (Is this patient potentially abusing OTC laxatives or taking OTC “cold” medicine containing an antihistamine?) Does the onset of constipation coincide with the taking of any of the medications listed in the MADE-O-FUN acrostic?
D. Does the past medical history, past surgical history, systems review, or chart review suggest any of the associated systemic illness listed in MADE-O-FUN? Is the patient known to have parkinsonism, renal failure, diabetes mellitus, hypertension (possibly treated with medications such as clonidine, calcium channel blockers, or potassium depleting diuretics, or other medications potentially causing decreased colonic tone), or hypothyroidism? Is there a history of cancer (potentially associated with hypercalcemia)?
Physical examination
Undertake a general physical examination looking for the stigmata of the associated constitutional illnesses mentioned in the MADE-O-FUN acrostic. Target the abdominal examination specifically for masses or abdominal tenderness and the rectal examination for fecal occult blood, rectal tone, rectal masses, rectal foreign body, impaction, anal fissure, hemorrhoids, or rectocoele—essential parts of the evaluation.
Diagnostic testing
Laboratory evaluation should consist of fecal occult blood testing (FOBT) looking for rectal bleeding; serum potassium and calcium to rule out hypokalemia and hypercalcemia (both associated with decreased colonic tone); serum glucose to evaluate possible diabetes; complete blood count looking for anemia (possibly related to chronic GI blood loss from tumor); blood urea nitrogen, serum creatinine, or both to rule out renal failure; and thyroid stimulating hormone to evaluate for hypothyroidism.
Visualize the lower colon via flexible sigmoidoscopy in patients aged more than 40 years whose constipation is of recent origin. Flexible sigmoidoscopy alone is insufficient for patients whose findings could suggest colonic neoplasia (melena, positive FOBT, hematochezia, abdominal mass, unexplained weight loss, or unexplained anemia). These patients should be offered either (a) colonoscopy or (b) barium enema plus flexible sigmoidoscopy.
Diagnostic assessment
The key diagnostic task in adults presenting with constipation is identifying those occasional patients whose constipation is caused by colorectal cancer. Because survival from colon cancer is directly related to the stage of the disease at time of diagnosis (3), patients whose history, examination, or laboratory findings are more suggestive of this diagnosis merit prompt investigation, including referral if necessary.
For patients whose constipation can be related to a particular systemic disease (e.g., hypercalcemia or hypothyroidism) or the use of particular medications (e.g., clonidine or an aluminum-containing antacid), identifying that link can be instrumental in ensuring that inciting issues are appropriately addressed in the management of the patient as a whole entity and not just as “a colon.”
In that greater host of patients whose initial evaluation suggests a more benign cause of constipation, or for whom constipation seems to be an incidental feature in an otherwise well individual, the decision to proceed with colonic visualization, or to begin a search for more unusual causes (the “U” in the MADE-O-FUN acrostic) will depend on the degree to which the constipation subjectively has an impact on the patient’s ability to live a fulfilling, happy, and rewarding life.
References
1. Drossman DA, McKee DC, Sandler RS, et al. Bowel patterns among subjects not seeking health care. Use of a questionnaire to identify a population with bowel dysfunction. Gastroenterology 1982;83:529–534.
2. Sonnenberg A, Koch TR. Physician visits in the United States for constipation: 1958–1986. Dig Dis Sci 1989;34:606–611.
3. Steele G. Colorectal cancer. In: Murphy GP, Lawrence W, Lenhad RE, eds. American Cancer Society textbook of clinical oncology, 2nd ed. Atlanta: The American Cancer Society, 1995:Chap 14.
Book Source Details
- Book Title: The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter
- Author(s): Robert B. Taylor (editor)
- Year of Publication: 2000
- Copyright Details: The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter, Copyright © 2000 Lippincott Williams & Wilkins.
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Copyright Details: The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter, Copyright © 2008 Williams & Wilkins.
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