Causes of Constipation

Acute constipation*

Bowel obstruction

Volvulus, hernia, adhesions, fecal impaction

Adynamic ileus

Peritonitis, major acute illness (eg, sepsis), head or spinal trauma, bed rest

Medications

Anticholinergics (eg, antihistamines, antipsychotics, antiparkinsonian medications, antispasmodics), cations (iron, aluminum, calcium, barium, bismuth), opioids, calcium channel blockers, general anesthetics

Constipation shortly after start of therapy with the medication

Chronic constipation*

Colonic tumor

Adenocarcinoma of sigmoid colon

Metabolic disorders

Diabetes mellitus, hypothyroidism, hypocalcemia or hypercalcemia, pregnancy, uremia, porphyria

Central nervous system disorders

Parkinson disease, multiple sclerosis, stroke, spinal cord lesions

Peripheral nervous system disorders

Hirschsprung disease, neurofibromatosis, autonomic neuropathy

Systemic disorders

Systemic sclerosis, amyloidosis, inflammatory myopathy, myotonic dystrophy

Functional disorders

Slow-transit constipation, irritable bowel syndrome, pelvic floor dysfunction (functional defecatory disorders)

Dietary factors

Low-fiber diet, sugar-restricted diet, chronic laxative abuse

Dyssynergic defecation

Asynchrony of anorectal muscles leading to difficult evacuation and constipation; typically, sensation of incomplete evacuation plus excessive straining and, particularly, digital disimpaction