Some Causes and Features of Constipation
Cause |
Examples/Common Features* |
Tests |
Acute constipation† |
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Acute intestinal obstruction |
Twisting of a loop of intestine (volvulus), hernia, adhesions, and fecal impaction Usually vomiting, crampy abdominal pain, and a distended abdomen |
Abdominal x-rays Sometimes CT |
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Ileus (temporary absence of the contractile movements of the intestine) |
Major acute illness, such as sepsis (a severe infection of the bloodstream) Immediately after abdominal surgery Recent head or spinal cord injury Prolonged bed rest |
Abdominal x-rays |
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Drugs |
Drugs with anticholinergic effects, such as antihistamines, some antidepressants, antipsychotic drugs, drugs used to treat Parkinson disease, and drugs that reduce or stop muscle spasms in the digestive tract (antispasmodic drugs) Drugs containing certain metals (iron, aluminum, calcium, barium, or bismuth) Opioids Calcium channel blockers Usually constipation that begins shortly after starting a new drug |
A doctor's examination to exclude other causes of constipation Sometimes stopping the drug to see whether constipation resolves |
Chronic constipation† |
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Often constipation that has recently developed, persists for weeks, and gradually worsens as the tumor grows Sometimes blood in stool (blood may be visible or detected during a doctor's examination) |
Colonoscopy with biopsy |
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Metabolic disorders |
Diabetes mellitus, an underactive thyroid gland (hypothyroidism), high levels of calcium in the blood (hypercalcemia), kidney failure, or pregnancy |
Blood tests |
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Central nervous system disorders (affecting the brain or spinal cord) |
MRI and/or CT |
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Peripheral nervous system disorders (affecting nerves outside the brain and spinal cord) |
A doctor’s examination Sometimes x-rays after barium is inserted in the rectum (barium enema) and/or biopsy |
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Systemic disorders |
Systemic sclerosis, amyloidosis, skin inflammation plus muscle inflammation and muscle degeneration (dermatomyositis), or weakness and stiff muscles (myotonic dystrophy) |
A doctor’s examination Sometimes biopsy and/or blood tests |
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Functional disorders |
Inactive colon (colonic inertia), irritable bowel syndrome, functional constipation, or disordered defecation Often a sense of a blockage in the anus and/or rectum, prolonged or difficult defecation, or excessive straining |
A doctor’s examination Sometimes sigmoidoscopy |
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Dietary factors |
Low-fiber diet or chronic laxative abuse |
A doctor’s examination |
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* Features include symptoms and the results of the doctor's examination. Features mentioned are typical but not always present. |
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† There is some overlap between causes of acute and chronic constipation. In particular, drugs are common causes of both. |
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CT = computed tomography; MRI = magnetic resonance imaging. |
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