Diagnostic imaging in the evaluation of constipation in adults.

Acute and chronic constipation are common conditions. In most instances, a thorough history and digital rectal examination provide sufficient information to begin treatment. Occasionally, imaging studies can be useful to confirm the presence of a suspected abnormality. The acute onset of constipation suggests colonic obstruction. Plain abdominal radiographs may be sufficient to determine the level and cause of the obstruction, such as sigmoid or cecal volvulus. Barium enema radiographic examination or colonoscopy may also be useful to detect the cause of obstruction. In patients with chronic constipation, plain abdominal radiographs can be used to show the extent of fecal impaction. Colonic transit time can be assessed on serial abdominal radiographs after the patient has ingested radiopaque markers. Evacuation proctography can be used to diagnose a variety of functional disorders of the rectum and anus, such as rectocele, intussusception and abnormal perineum floor descent.