Chapter 22: Constipation

INTRODUCTION

• Constipation has been defined as difficult or infrequent passage of stool, at times associated with straining or a feeling of incomplete defecation.

PATHOPHYSIOLOGY

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

• Constipation commonly results from a diet low in fiber, inadequate fluid intake, decreased physical activity, or from use of constipating drugs such as opiates. Constipation may sometimes be psychogenic in origin.

• Diseases or conditions that may cause constipation include the following:

  • ✓ Gastrointestinal (GI) disorders: Irritable bowel syndrome (IBS), diverticulitis, upper and lower GI tract diseases, hemorrhoids, anal fissures, ulcerative proctitis, tumors, hernia, volvulus of the bowel, syphilis, tuberculosis, lymphogranuloma venereum, and Hirschsprung disease

  • ✓ Metabolic and endocrine disorders: Diabetes mellitus with neuropathy, hypothyroidism, panhypopituitarism, pheochromocytoma, hypercalcemia, and enteric glucagon excess

  • ✓ Pregnancy

  • ✓ Cardiac disorders (eg, heart failure)

  • ✓ Neurogenic constipation: Head trauma, CNS tumors, spinal cord injury, cerebrospinal accidents, and Parkinson disease

  • ✓ Psychogenic causes

• Causes of drug-induced constipation are listed in Table 22–1. All opiate derivatives are associated with constipation, but the degree of intestinal inhibitory effects seems to differ among agents. Orally administered opiates appear to have greater inhibitory effect than parenterally administered agents; oral codeine is well known as a potent antimotility agent.

CLINICAL PRESENTATION

• Table 22–2 shows the general clinical presentation of constipation.

• The patient should also be carefully questioned about usual diet and laxative regimens.

• General health status, signs of underlying medical illness (ie, hypothyroidism), and psychological status (eg, depression or other psychological illness) should also be assessed.

• Patients with alarm symptoms, a family history of colon cancer, or those older than 50 years with new symptoms may need further diagnostic evaluation.