Jonathan A. Maisel
EPIDEMIOLOGY
Constipation is the most common digestive complaint in the United States.
Criteria for the diagnosis of constipation include the following:
Less than three bowel movements per week
Hard stools, straining at defecation, and/or incomplete evacuation at least 25% of the time
PATHOPHYSIOLOGY
Fluid intake, fiber intake, exercise, medications, toxins, anatomic lesions, gut flora, hormone levels, and a host of medical and psychiatric conditions can affect gut motility.
CLINICAL FEATURES
Several historical features may be helpful in eliciting the cause, including new medications or dietary supplements, a decrease in fluid or fiber intake, or a change in activity level.
Acute onset implies obstruction until proven otherwise. Associated symptoms, such as vomiting, abdominal distention, and inability to pass flatus, further suggest obstruction.
A history of unexplained weight loss, rectal bleeding, change in stool caliber, or unexplained iron deficiency anemia suggests colon cancer. A family history of colon cancer would escalate one’s suspicion.
Associated illnesses can help disclose the underlying diagnosis: cold intolerance (hypothyroidism), diver-ticulitis (inflammatory stricture), or nephrolithiasis (hyperparathyroidism).
Diarrhea alone does not rule out constipation/obstruction, as liquid stool can pass around an obstructive source.
Physical examination should focus on detection of hernias or abdominal masses.
Bowel sounds will be decreased in the setting of slow gut transit, but increased in the setting of obstruction.
Rectal examination will detect masses, foreign bodies, hemorrhoids, abscesses, fecal impaction, anal fissures, or fecal blood. The latter, accompanied by weight loss or decreasing stool caliber, may confirm the presence of colon cancer.
Fecal impaction itself can cause rectal bleeding from stercoral ulcers.
The presence of ascites in postmenopausal women raises suspicion of ovarian or uterine carcinoma.
DIAGNOSIS AND DIFFERENTIAL DIAGNOSIS
The differential diagnosis of constipation is extensive, as noted in Table 40-1.
Directed testing in acute constipation, based on level of suspicion, can include a complete blood count (to rule out anemia), thyroid panel (to rule out hypothy-roidism), and electrolyte determinations (to rule out hypokalemia or hypercalcemia).
Flat and erect abdominal radiographs may be useful in confirming obstruction or assessing stool burden.
CT scan of the abdomen and pelvis with IV and PO contrast may be necessary to identify bowel obstruction or other organic causes of constipation
Chronic constipation is usually a functional disorder that can be worked up on an outpatient basis. However, complications of chronic constipation, such as fecal impaction and intestinal pseudo-obstruction, will require either manual, colonoscopic, or surgical intervention.
TABLE 40-1 Differential Diagnosis of Constipation.
EMERGENCY DEPARTMENT CARE AND DISPOSITION
Treatment of functional constipation is directed at symptomatic relief, as well as addressing lifestyle issues.
Occasionally, specific treatment is required for complications of constipation, or for underlying disorders that can lead to organic constipation.
The most important prescription for functional constipation is a dietary and exercise regimen that includes fluids (1.5 L daily), fiber (10 grams daily), and exercise. Fiber in the form of bran (one cup daily) or psyllium (Metamucilat one teaspoon three times a day) increases stool volume and gut motility.
Medications can provide temporary relief.
Stimulants can be either given PO, as with anthraquinones (eg, Peri-Colace 1–2 tablets PO daily or twice daily), or PR, as with bisacodyl (eg, Dulcolax 10 mg PR three times daily in adults or children).
In the absence of renal failure, saline laxatives such as milk of magnesia 15 to 30 mL PO once or twice a day, or magnesium citrate 240 mL PO once a day, are useful.
Hyperosmolar agents, such as lactulose or sorbitol 15 to 30 mL PO once or twice a day may be helpful, as is polyethylene glycol (eg, MiraLAX 17 grams PO).
In children, glycerine rectal suppositories, or mineral oil (age 5–11 years : 5–15 mL PO daily; age >12 years : 15–45 mL PO daily) have been advocated.
Enemas of soapsuds (1500 mL PR) or phosphate (eg, Fleets 1 unit PR, 1 oz/10 kg in children) are generally reserved for severe cases or after fecal dis-impaction. Use care to avoid rectal perforation.
Fecal impaction should be removed manually using local anesthetic lubricant and parenteral analgesia or sedation as required. In female patients, transvaginal pressure with the other hand may be helpful. An enema or suppositories to complete evacuation can follow. Following disimpaction, a regimen of medication should be prescribed to reestablish fecal flow.
All patients with apparent functional constipation can be managed as outpatients. Early follow-up is indicated in patients with recent severe constipation; chronic constipation associated with systemic symptoms, such as weight loss, anemia, or change in stool caliber; refractory constipation; and constipation requiring chronic laxative use.
Patients with organic constipation from obstruction require hospitalization and surgical evaluation. Intestinal pseudo-obstruction and sigmoid volvulus can sometimes be corrected colonoscopically.
For further reading in Tintinalli’s; Emergency Medicine: A Comprehensive Study Guide, 7th ed., see Chapter 77, “Acute and Chronic Constipation,” by Vito Rocco and Paul Krivickas.