Unenhanced CT less accurate than contrast-enhanced CT for diagnosing acute abdominal pain in ED: JAMA

"This should be balanced with the risk of intravenous contrast medium administration to patients with risk factors for hypersensitivity reaction or kidney injury," the researchers wrote in their study published in JAMA Surgery.

IV contrast medium is sometimes withheld in patients undergoing computed tomography for abdominal pain due to the lack of availability or risk of complications. The risk from withholding contrast medium is not being studied well. Therefore, Hiram Shaish, Columbia University, New York, New York, and colleagues aimed to determine the diagnostic accuracy of unenhanced abdominopelvic CT using contemporaneous contrast-enhanced CT as the reference standard in ED patients with acute abdominal pain.

The study included 201 consecutive adult ED patients who underwent dual-energy contrast-enhanced CT to evaluate acute abdominal pain. Three blinded radiologists interpreted these scans to establish the reference standard by majority rule. Then, IV and oral contrast media were digitally subtracted using dual-energy techniques. Six blinded radiologists from 3 institutions interpreted the resulting unenhanced CT examination. Participants included a consecutive sample of ED patients with abdominal pain who underwent dual-energy CT.

The study's primary outcome was the diagnostic accuracy of unenhanced CT for primary (main cause[s] of pain) and actionable secondary diagnoses (incidental findings requiring management). The Gwet interrater agreement coefficient was calculated.

The authors reported the following findings:

• There were 201 included patients (female, 108; male, 93) with a mean age of 50.1 years and a mean BMI of 25.5.
• The overall accuracy of unenhanced CT was 70% (faculty, 68% to 74%; residents, 69% to 70%).
• Faculty had higher accuracy than residents for primary diagnoses (82% vs 76%; adjusted odds ratio [OR], 1.83) but lower accuracy for actionable secondary diagnoses (87% vs 90%; OR, 0.57).
• This was because faculty made fewer false-negative primary diagnoses (38% vs 62%; OR, 0.23) but more false-positive actionable secondary diagnoses (63% vs 37%; OR, 2.11).
• False-negative (19%) and false-positive (14%) results were common. Interrater agreement for overall accuracy was moderate (Gwet agreement coefficient, 0.58).

"The use of unenhanced CT In a general population of emergency department patients with abdominal pain to avoid risks of intravenous contrast medium administration was linked with a large diagnostic penalty," the researchers conclude.

Reference:

Shaish H, Ream J, Huang C, et al. Diagnostic Accuracy of Unenhanced Computed Tomography for Evaluation of Acute Abdominal Pain in the Emergency Department. JAMA Surg. Published online May 03, 2023. doi:10.1001/jamasurg.2023.1112