Constipation

SOURCE

Source: Fabel PH, Shealy KM. Diarrhea, constipation, and irritable bowel syndrome. In: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM, eds. Pharmacotherapy: A Pathophysiologic Approach. 10th ed. New York, NY: McGraw-Hill; 2017. http://accesspharmacy.mhmedical.com/content.aspx?bookid=1861&sectionid=146059459. Accessed April 13, 2017.

DEFINITION

• Functional constipation is bowel disorder characterized by difficult, infrequent, or seemingly incomplete defecation that does not meet criteria for irritable bowel syndrome (IBS).¹

ETIOLOGY

• Constipation may be primary (occurs without underlying identifiable cause) or secondary (result of constipating drugs, lifestyle factors, or medical disorders).

PATHOPHYSIOLOGY

• Constipation is not a disease but symptom of underlying disease or problem.

• Drugs that inhibit neurologic or muscular function of gastrointestinal (GI) tract, particularly colon, may result in constipation (Table 1).

  • All opiate derivatives associated with constipation to varying degrees.

  • Orally administered opiates appear to have greater inhibitory effect than parenterally administered agents.

EPIDEMIOLOGY

• Prevalence depends on the definition used and whether the condition is self-reported or provider-diagnosed.

• Prevalence in North America ranges from 12% to 19%.

• More common in women and the elderly.

PREVENTION

• Increase dietary fiber.

• Initiate agents to soften stool when opiates are started.

• Increase activity level.

RISK FACTORS

• Lack of activity.

• Lower socioeconomic status.

• Lower income.

• Symptoms of depression.

• History of physical or sexual abuse.

CLINICAL PRESENTATION

SIGNS AND SYMPTOMS

• Infrequent bowel movements.

• Stools that are hard, small, or dry.

• Difficulty or pain on defecation.

• Feeling of abdominal discomfort or bloating.

• Incomplete evacuation.

DIAGNOSIS

MEANS OF CONFIRMATION AND DIAGNOSIS

• History and physical examination to clarify what patient means by constipation. Ask specifically about alarm signs and symptoms:

  • Hematochezia.

  • Melena.

  • Family history of colon cancer.

  • Family history of inflammatory bowel disease.

  • Anemia.

  • Weight loss.

  • Anorexia.

  • Nausea.

  • Vomiting.

  • Persistent constipation refractory to treatment.

  • New onset or worsening constipation in elderly patients without evidence of primary cause.

• Rectal examination should be performed for presence of anatomical abnormalities, stricture, rectal mass, or fecal impaction.

• Identify underlying secondary causes or conditions.