The chief, and perhaps the sole, reason for contemplating invasive investigation of constipated elderly patients is the detection of treatable carcinoma of the colon or rectum. Colorectal carcinoma has a reasonably good prognosis with early treatment. Even when spread has occurred, subsequent quality of life may be substantially enhanced by treatment. In light of this knowledge, many authors advocate a work-up of every constipated patient, to include a sigmoidoscopy and barium enema or colonoscopy. While this approach may make some sense for consultant gastroenterologists, it is absurd advice to offer primary care physicians.
Based on United States incidence figures, an Ontario family physician who had a 3,000 patient practice with an age distribution corresponding to the provincial population could expect to encounter a new case of colorectal carcinoma once every 16 months among his geriatric patients. Given the fact that one in four elderly regards himself as constipated, investigation must clearly be done selectively.
Aggressive investigation should be considered under the following circumstances:
1. Constipation of recent onset without obvious cause
2. Aggravation of existing constipation without obvious cause
3. Constipation with unexplained abdominal mass
4. Constipation with recent onset of unexplained abdominal pain
5. Constipation with melena
6. Constipation with rectal bleeding not obviously due to anal pathology such as fissure or hemorrhoids. (Dark blood, blood with clots, blood well mixed with mucous or blood mixed with or adherent to stools should not be attributed to anal lesions).
Even when one of the above conditions applies, a decision not to investigate may be appropriate in patients with terminal or severely debilitating illness. Most demented patients will not cooperate sufficiently to permit a satisfactory sigmoidoscopy or barium enema to be carried out.
Sigmoidscopy is generally less traumatic for the elderly than a barium enema. Some 50-75% of all colorectal neoplasms occur within sigmoidoscopic range. Hodkinson, a British geriatrician who advocates fairly liberal recourse to sigmoidoscopy, makes the following comment:
“Barium enema should not be undertaken without careful consideration as the diagnostic yield is very low for cancer of the colon unless an abdominal mass is palpable, and many enemas in old people are technically unsatisfactory because of the difficulties of bowel preparation. The examination is often taxing as well as unpleasant for the elderly patient”.
Newly identified constipated patients who do not meet the criteria for intensive investigation should certainly have a rectal examination and probably a series of three consecutive stools for occult blood while on a meat-free diet. The meat-free diet is essential in order to avoid subjecting large numbers of patients with false positive results to the unpleasantness of a sigmoidoscopy and barium enema. Those with positive stools should be considered for sigmoidoscopy and barium enema.
All patients should be reassessed after a period of whatever treatment is decided upon. Those who respond poorly to apparently appropriate treatment may need to be investigated.