When evaluating a patient for suspected acute bowel perforation, what is the MOST appropriate initial imaging modality?
Computed tomography (CT) of the abdomen with contrast
Magnetic resonance imaging (MRI) of the abdomen
Plain abdominal films
Ultrasonography of the abdomen
It is important to recognize that surgical consultation should not be delayed awaiting the results of imaging in the acute abdomen. If imaging is obtained in cases of suspected acute bowel perforation, then the most appropriate initial imaging modality is plain abdominal films as they are relatively easy to obtain, and free air visible on a plain abdominal film mandates immediate surgical evaluation without the need for additional imaging. However, abdominal plain films cannot rule out perforation. Up to 20% of patients with perforation will not demonstrate free air. Ultrasonography is the preferred modality for the evaluation of the biliary tract. It may be a more sensitive test than abdominal plain films for the detection of free air, but it is highly operator dependent, requires specialized equipment, and is limited by obesity and overlying gas. While CT scan of the abdomen is superior in identifying free air when compared with plain abdominal films, it is associated with significant delays due to the administration of contrast and radiologist interpretation. Cholescintigraphy and MRI of the abdomen do not have a role in the initial evaluation of suspected acute bowel perforation.