CT Without Oral Contrast Saves Time, Maintains Quality

James Brice

July 06, 2012

July 6, 2012 — An emergency department (ED) strategy that eliminates the routine use of oral contrast for abdominal-pelvic (AP) computed tomography (CT) for undifferentiated abdominal pain can reduce ED length of stay (LOS) without compromising diagnostic accuracy.

Robin B. Levenson, MD, and colleagues from the Emergency Radiology Division of Beth Israel Deaconess Medical Center, Boston, Massachusetts, found the rescan rate with oral contrast was modest after the staff stopped routinely administering oral contrast for these procedures. Their findings were drawn from the clinical experience with a cohort of 1014 consecutive ED patients who underwent AP CT with oral contrast compared with that of a subsequent group of 987 patients who had AP CT without oral contrast.

The study found additional CT scans with oral contrast rarely affected the results of the initial reading in any case. In patients admitted to the hospital, additional abdominal pelvic imaging during their stay did not alter their diagnosis.

Dr. Levenson and colleagues found no statistically significant difference in the rate of return to the ED in the 72 hours after discharge for patients who underwent CT without oral contrast compared with those who had conventional AP CT with contrast.

Oral CT contrast administration adds time to ED visits, noted Dr. Levenson and colleagues in the study, published online June 29 in Emergency Radiology. Multidetector CT is delayed 60 to 90 minutes to allow oral contrast to opacify the bowel.

Several studies have demonstrated that AP CT without oral contrast leads to accurate evaluations of abdominal pain, especially for suspected acute appendicitis. The Beth Israel Deaconess group sought to assess the effect of AP CT without oral contrast on ED LOS.

The current researchers showed, as hypothesized, that the routine use of oral contrast for AP CT was not necessary for patients with nontraumatic, undifferentiated abdominal pain.

Oral contrast was still ordered, however, for patients with a known history of inflammatory bowel disease, gastrointestinal tract–altering surgery, or extremely lean body habitus, Dr. Levenson and colleagues write.

The study did not consider patients with symptoms that have not traditionally led to oral contrast before AP CT. Indications excluding patients from the study were trauma, a suspected genitourinary stone, hemodynamic instability, suspected mesenteric ischemia, retroperitoneal hematoma, aortic rupture/dissection, and suspected pulmonary embolism.

Before the protocol change, 95% of patients eligible for oral contrast received it before AP CT. Afterward, the proportion dropped to a statistically significant 42% (P < .001). ED LOS was cut by a mean of 97.7 minutes (P < .001), and the time between an order for CT and the actual procedure fell by 66.2 minutes (P < .001).

"As our study demonstrates, elimination of routine oral contrast used in the ED for patients eligible for oral contrast may lead to decrease in patient time from CT ordered to CT performed and in mean ED LOS," the authors write.

In terms of diagnostic quality, no patient had repeat CT with oral contrast during the initial ED episode or a 72-hour return visit to the ED that resulted in a change in CT diagnosis.

Study limitations include the retrospective design, lack of follow-up to verify accuracy of diagnoses, inability to assess whether discharged patients presented to a different hospital, and radiologic assessment by only 1 attending radiologist.

The authors note that Beth Israel Deaconess continues to administer oral contrast before AP CT for patients who have a history of gastrointestinal tract–altering surgery or inflammatory bowel disease or who are subjectively thin. More study and analysis are needed before CT without oral contrast can be justified for these patients, the authors write.

The published study did not include a statement that would have identified any potential conflicts of interests among the investigators.

Emerg Radiol. Published online June 29, 2012. Abstract