A physical examination in patients with constipation reveals abdominal tenderness and the presence or absence of bowel sounds. A rectal examination helps determine whether an anatomical or physiologic cause of obstruction is present. Several diagnostic tests are helpful, including abdominal radiography to look for signs of obstruction. CT is used to check for masses or areas of obstruction. Direct visualization with anoscopy or colonoscopy is often helpful in determining an anatomical etiology for constipation. Laboratory evaluation does not play a large role in the initial assessment of a patient with constipation.
Various imaging studies are used to investigate for acute processes that may be causing colonic ileus, and to evaluate for causes of chronic constipation. In patients with acute abdominal pain, fever, leukocytosis, or other symptoms that suggest systemic or intra-abdominal processes, imaging studies are used to rule out sources of sepsis or other intra-abdominal concerns.
Colonic transit study, defecography, lower gastrointestinal endoscopy, surface anal electromyography, anorectal manometry, and balloon expulsion may also be used in the evaluation of constipation. In an acute situation with a patient who is usually not constipated and who is not at high risk for a serious condition, sometimes no further evaluation is necessary. Sigmoidoscopy, barium enema, or colonoscopy may be considered for colorectal cancer screening in patients older than 50 years. The current criterion standard is colonoscopy.
Diabetic gastroparesis can present with fecal impaction. This may be seen in patients with diabetic neuropathy. Scleroderma and other connective-tissue diseases may be complicated by motor disturbances that mimic colonic obstruction on plain films. Myxedema ileus is a result of hypothyroidism.
If no anatomical lesion is noted on rectal examination, abnormal physiology should be suspected. Anorectal manometry documents several parameters, including external anal sphincter and puborectalis function, reflex relaxation of the internal sphincter when the rectum is distended, coordination of these muscles during the bear-down phase of defecation, anorectal pressures during these events, and the threshold at which rectal distention is perceived.
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Cite this: Winston Tan, Matthew Tan. A 61-Year-Old Woman With Painful Constipation - Medscape - Oct 12, 2017.