Imaging of the nontraumatic acute abdomen.

Plain-film radiography of the abdomen is often the first-line imaging modality used for the patient in the ED. It is capable of demonstrating abnormal locations of gas, abnormal viscera, calcifications and foreign material, and skeletal and lower lung pathology. PFR findings may aid in the decision to proceed to other modalities. Contrast studies have a limited role in the ED but may be necessary to diagnose disease inadequately visualized by PFR, as in the case of perforated duodenal ulcer, missed on PFR in approximately 15 per cent of cases. Ultrasound is most useful in the ED for obstetric and gynecologic illness, as well as disorders of the hepatobiliary system. Nuclear medicine studies can be very useful for GI bleeding and inflammatory conditions but may not always be as available or convenient as other modalities. CT has very broad usefulness. Angiography is very useful for locating bleeding sites, especially in the large bowel, and for determination of mesenteric arterial patency in suspected mesenteric ischemia. Finally, MRI, which has enormous potential, is not funded by many third-party payment plans for use in emergencies, and must overcome certain obstacles before it assumes common usage in the ED.