Constipation

Diagnosis Table 4. Evidence-based Summary of the Utility of the Diagnostic Tests for Chronic Constipation Test Blood tests (thyroid function tests, serum calcium, glucose, electrolytes) Imaging Tests Plain abdominal radiograph Barium enema Defecography Magnetic resonance imaging defecography Flexible sigmoidoscopy and colonoscopy Physiological testing Colonic transit study with radiopaque markers Colonic transit study with scintigraphy Colonic transit with wireless motility capsule (WMC) Anorectal manometry Balloon expulsion test (BET) Evaluate presence of slow, normal, or rapid colonic transit; inexpensive and widely available Evaluate presence of slow, normal, or rapid colonic transit; provide evaluation of whole gut transit Standardized, no radiation, validated technique; provides regional and whole gut transit time Identify dyssynergic defecation, rectal hyposensitivity, rectal hypersensitivity, impaired compliance, Hirschsprung's disease Simple, inexpensive, bedside assessment of the ability to expel a simulated stool; identify dyssynergic defecation Colonic manometry Identify colonic motor dysfunction, facilitating selection of patients for surgery Inconsistent methodology; validity has been questioned. Radiation exposure increased with multiple x-rays Expensive, time consuming, availability, lack of standardization, radiation exposure Availability, expensive Lack of standardization Identify excessive amount of stool in the colon; simple, inexpensive, widely available Lack of standardization on how to review the image, lack of controlled studies, radiation exposure Identify megacolon, megarectum, stenosis, diverticulosis, extrinsic compression, and intraluminal masses Identify dyssynergia, rectocele, prolapse, excessive perineal descent, megarectum, Hirschsprung's disease Simultaneously evaluate global pelvic floor anatomy, sphincter morphology, and dynamic motion Direct visualization of the colon to exclude mucosal lesions such as solitary rectal ulcer syndrome, inflammation, or malignancy Lack of standardization, embarrassing for patients, radiation exposure, lack of controlled studies Radiation exposure, embarrassment, availability, interobserver bias, inconsistent methodology Expensive, lack of standardization, availability (particularly if dynamic MRI) Invasive, risks related to the procedure (perforation, bleeding) and sedation Clinical Utility Rule out systemic or metabolic disorder Weakness Is not a cost-effective strategy Lack of standardization Invasive, not widely available, lack of standardization 4 Remes-Troche JM, Rao SS. Diagnostic testing in patients with chronic constipation. Curr Gastroenterol Rep. 2006;8(5):416-424. Sackett DL. Rules of evidence and clinical recommendations on use of antithrombotic agents. Chest. 1986;89(2 Suppl):2S-3S.

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