Constipation

Basics

Unsatisfactory defecation characterized by infrequent stools, difficult stool passage, or both
Characteristics include <3 bowel movements a week, hard stools, excessive straining, prolonged time spent in the restroom, a sense of incomplete evacuation, and abdominal discomfort/bloating.

Description

Geriatric Considerations
Consider new-onset constipation after age 50 years a “red flag” for colorectal neoplasms. Use warm water enemas (instead of sodium phosphate enemas) for impaction in geriatric patients. Sodium phosphate enemas in older adults have been associated with hypotension, volume depletion, EKG changes (prolonged QT interval), and severe electrolyte disturbances.

Pediatric Considerations
Consider Hirschsprung disease in cases of pediatric constipation. This accounts for 25% of all newborn intestinal obstructions and can present as milder cases diagnosed in older children with chronic constipation, abdominal distension, and decreased growth. Hirschsprung has a 5:1 male-to-female ratio and is associated with inherited conditions (e.g., Down syndrome).

Pregnancy Considerations
Constipation is common in pregnancy due to progesterone slowing GI motility, gravid pressure of uterus on colon, iron supplementation, and decreased physical activity.

Epidemiology

More pronounced in children and elderly
Predominant sex: female > male (2:1)
Nonwhites > whites

Incidence

5 million office visits annually
100,000 hospitalizations

Prevalence

16% of adults >18 years of age, rising to 33% of adults >60 years of age
3% of pediatric visits relate to constipation.

Etiology and Pathophysiology

Defecation reflex is a reflex that can be inhibited by voluntarily contracting the external sphincter or facilitated by straining to contract the abdominal muscles while voluntarily relaxing the anal sphincter. Rectal distention initiates the defecation reflex. The urge to defecate occurs with an increase in rectal pressure. Distention of the stomach also initiates rectal contractions and a desire to defecate (gastrocolic reflex).

Risk Factors

Extremes of age
Female sex
Polypharmacy
Sedentary lifestyle or condition
Low-fiber diet and inadequate fluid intake
Increased stress or history of abuse

General Prevention

High-fiber diet, adequate fluids, exercise, and training to “obey the urge” to defecate

Commonly Associated Conditions

General debilitation (disease or aging)
Dehydration
Hypothyroidism
Electrolyte abnormalities: hypokalemia, hypercalcemia

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