567 - Accuracy of Visualizing the Appendix using Non-Contrast Computer Tomography in the Pediatric Emergency Department

Publication Number: 567.3664

Tasnima Mohaimin, Albert Einstein College of Medicine, Wantagh, NY, United States; James Meltzer, Albert Einstein College of Medicine, Bronx, NY, United States; Bernard Goldwasser, Albert Einstein College of Medicine, Bronx, NY, United States; Sandra J. Cunningham, Jacobi Medical Center, New York, NY, United States

Background: Contrast-enhanced abdominopelvic computed tomography (CT) is often performed for the diagnosis of appendicitis. Studies have shown that CT without any enteric or intravenous contrast (IV) is accurate in detecting suspected appendicitis in older adults; however, this has not been well-studied in younger patients. Many issues arise when using contrast such as the difficulty in delivering a large volume of oral contrast, the recommended two-hour wait time to facilitate maximal visualization on CT, potential for allergic reactions, procedural aversion and discomfort of rectal contrast, and possible increase in radiation dose delivered from CT in children. Our institutions’ protocol uses both enteric and IV contrast when performing CT for suspected appendicitis. From May 2022 - December 2022, there was a national shortage of contrast material and clinicians were asked to limit its use. This provided a unique opportunity to study how well the appendix could be visualized in non-contrast CTs.

Objective: To determine whether the absence of contrast in CT scans affects the ability to identify the appendix in the pediatric population.

Design/Methods: This was a retrospective cohort study of patients < 21 years old who presented to the pediatric emergency department and underwent an abdominopelvic CT for any complaints during the period of contrast shortage. Patients with a prior appendectomy were excluded. For patients who underwent repeat CT scans, only the initial scan was included. Data abstracted from medical records included baseline characteristics (BMI, age, gender, hospital type, CT indication). A single pediatric radiologist reviewed all CT scans without knowledge of prior interpretation and determined whether the appendix could be visualized. We compared patients who had no contrast to those who had any type of contrast, and adjusted for baseline characteristics using multivariable logistic regression.

Results: A total of 196 patients had abdominopelvic CTs during the study period. The median age was 18(IQR 15,19) years, mean BMI 25(sd 7) kg/m2, and 105(54%) patients were female. Overall, 129(66%) patients were non-trauma, 153(78%) presented to the academic center, and 104(53%) did not receive any contrast. The appendix was visualized in 82(79%) patients in the non-contrast group versus 72(78%) in the contrast group (p=0.92). Moreover, the use of contrast was not associated with better visualization of the appendix after adjusting for baseline characteristics (aOR 1.0 [95% CI 0.5 -2.2]).

Conclusion(s): Among all patients undergoing abdominopelvic CTs, contrast did not enhance identification of the appendix.