Best Imaging Study for Evaluating Constipation

Initial Assessment Approach

The American Gastroenterological Association recommends a thorough digital rectal examination that includes assessment of pelvic floor motion during simulated evacuation before ordering imaging studies 3, 4
Laboratory testing should be limited to a complete blood count in the absence of other symptoms and signs, as recommended by the American Gastroenterological Association 1, 2
The American Gastroenterological Association suggests that metabolic tests, such as glucose, calcium, and thyroid-stimulating hormone, are not routinely recommended unless clinical features warrant them, with a strength of evidence rated as moderate 2, 3

The American Gastroenterological Association indicates that structural imaging is necessary in the presence of alarm symptoms, such as blood in stools, anemia, or weight loss, with a high strength of evidence 1, 3
Abrupt onset of constipation is another indication for structural imaging, as recommended by the American Gastroenterological Association, with a moderate strength of evidence 2, 4
Age over 50 years without previous colorectal cancer screening also warrants structural evaluation, according to the American Gastroenterological Association, with a high strength of evidence 1, 2

The American Gastroenterological Association recommends colonoscopy as a first-line option for structural imaging, due to its ability to provide direct visualization and biopsy capability, with a high strength of evidence 1, 2
CT colonography is an excellent alternative when colonoscopy is contraindicated, as suggested by the American Gastroenterological Association, with a moderate strength of evidence 2, 3
Flexible sigmoidoscopy with barium enema is an effective combination for structural imaging, according to the American Gastroenterological Association, with a moderate strength of evidence 1, 2

The American Gastroenterological Association recommends colonic transit studies using radiopaque markers to assess for slow transit constipation in patients with persistent symptoms, with a moderate strength of evidence 1, 3
Defecography, either fluoroscopic or MR, is recommended for suspected defecatory disorders, as suggested by the American College of Radiology, with a moderate strength of evidence 5, 6

The American College of Radiology recommends fluoroscopic cystocolpoproctography as one of the initial tests of choice, with a high strength of evidence 5
MR defecography provides high soft-tissue contrast resolution for direct visualization of pelvic organs and floor muscles, as recommended by the American College of Radiology, with a moderate strength of evidence 5, 6

The American Gastroenterological Association advises against relying solely on plain abdominal radiographs for diagnosis of constipation, due to their limited utility, with a low strength of evidence 5
Failing to consider functional disorders when structural imaging is normal is a common pitfall, as warned by the American College of Radiology, with a moderate strength of evidence 5
Overlooking the need for structural evaluation in high-risk patients, such as those with alarm symptoms or age over 50 without previous colorectal cancer screening, is a critical mistake, as emphasized by the American Gastroenterological Association, with a high strength of evidence 1, 2
Ordering excessive testing without clinical indication is not recommended, as cautioned by the American Gastroenterological Association, with a moderate strength of evidence 1, 3