Not all patients with undifferentiated abdominal pain in the emergency department require this treatment. Fine tuning our usage of oral contrast will decrease wait times and improve patient care.
Abdominal pain is a common chief complaint in the emergency department setting representing approximately 7% of all annual ED visits . A significant number of these patients receive an abdominopelvic CT scan to further assess their complaint. Over the last twenty-five years, the dependence upon and utilization of CT scans with both oral and IV contrast for undifferentiated abdominal pain has increased dramatically . This has led to extended wait times in the emergency department, delays in diagnosis, and patient exposure to potentially dangerous contrast material.
Traditionally both oral and intravenous (IV) contrast have been administered to patients undergoing CT scan imaging for undifferentiated abdominal pain. Oral contrast has several disadvantages. It requires time to administer (1-2 hours) and may contribute to delays in diagnosis. Oral contrast is difficult to tolerate in patients experiencing severe nausea and vomiting. Additionally, oral contrast does not reach the appendix in as many as 30% of patients and creates increased hydrostatic pressure in the colon that may lead to intestinal perforation [3-5].
It is important to also consider that advances in CT scan technology have significantly improved over the last twenty-five years. The utilization of multi-detector computer tomography and isotropic multi-planar reconstruction have led to higher-quality diagnostic images . Given the advances in imaging technology and interpretation, several studies have recently been published suggesting that oral contrast is not always necessary to achieve diagnostic accuracy.
A 2014 prospective multi-centered comparative effectiveness study looked at over 9,000 patients that underwent CT scan for suspected appendicitis. Roughly half of the study participants underwent CT scan with IV contrast alone. The remainder underwent CT scan with both IV and oral contrast. The study found that there was no difference in concordance between IV-alone and IV + oral contrast, thus concluding that oral contrast does not improve the evaluation of appendicitis. The study also found statistically significant data demonstrating that including oral contrast delays the time it takes to get to the operating room by nearly one full hour .
A 2005 meta-analysis looked at 23 studies, 19 of which were prospective and included 3,400 patients undergoing CT scan for suspected appendicitis with and without oral contrast material. The review demonstrated that non-contrast CTs are faster, less burdensome, and may have better diagnostic accuracy when compared to studies that include oral contrast. Collective data demonstrated contrast vs. no oral contrast sensitivities were 92% vs. 95%, specificities were 94% vs. 97%, and diagnostic accuracy was 92% vs. 96% (all statistically significant with p values < 0.1). This meta-analysis clearly demonstrates that CT scan without contrast is to superior contrast-enhanced CT scans for suspected appendicitis .
A 2012 study published in Emergency Radiology looked at eliminating routine oral contrast use for CT scanning in the emergency department as it pertains to patient throughput and diagnosis. The study enrolled over 2,000 patients undergoing CT scan at a high volume, tertiary urban emergency department and found that eliminating oral contrast decreased emergency department length of stay by 97 minutes and mean time to CT scan by 66 minutes. All patients that received a CT scan negative for acute findings received no additional subsequent imaging that led to a change in diagnosis and the study showed no statistically significant difference in outcomes between the two groups during return ED visits .
Regarding outcomes the results were limited. The study looked at return ED visits for those that were discharged with and without OC and found no statistically significant outcomes between the two groups. So it demonstrated equivalence but not superiority.
In addition to these studies, both ACR and ACEP advocate for a more responsible utilization of oral contrast. The current American College of Radiology Guidelines recommends: “Considering the increased examination time, problems with patient tolerance, and potential increased radiation exposure in patients from CT scan in patients with high-density enteric contrast, evidence is trending against the routine use of oral contrast for CT scan when IV contrast is used .” Similarly, the American College of Emergency Physicians published a clinical policy regarding the evaluation and management of emergency department patients with suspected appendicitis. The policy recommends that adult patients with suspected appendicitis may undergo CT scan with or without contrast .
It is important to note that oral contrast may improve the diagnostic accuracy of abdominal CT scans in some circumstances. Both IV and oral contrast may be beneficial in individuals with low body mass index who lack sufficient mesenteric fat to demonstrate periappendiceal fat stranding associated with appendicitis [12,13]. Two studies suggest that oral contrast may be beneficial in individuals with a BMI≤25 due to their lack of mesenteric fat [14,15]. Oral contrast may also prove useful in individuals with inflammatory bowel disease, gastric perforation, and in those with a history of bowel altering surgery with a clinical suspicion of intestinal obstruction. ACEP clinical policy currently states that diagnostic imaging with oral contrast is not required in the evaluation of blunt abdominal trauma (Level B Recommendation).
Who Should Receive Oral Contrast
- BMI ≤ 25
- Suspect Bowel Obstruction
- Suspect Gastric Perforation
- History of Inflammatory Bowel Disease
- History of Bowel Altering Surgery
In summary, the concept of eliminating the routine use of oral contrast is not new. Advances in imaging technology and interpretation have led to improved radiographic diagnostic accuracy. Several well-designed clinical studies have demonstrated similar specificity, sensitivity, and diagnostic accuracy when comparing CT scan with and without oral contrast. Additionally, both the American College of Radiology and the American College of Emergency Medicine advocate for a more appropriate utilization of oral contrast. This evidence-based approach to limiting oral contrast with abdominal CT scans will decrease wait times in the emergency department and help us provide better care to our patients.
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