Unenhanced CT provides value for older patients with acute abdominal pain

Unenhanced CT is effective for treating older patients presenting in the emergency department (ED) with acute abdominal pain (AAP), according to new findings published in Diagnostic and Interventional Imaging.

“Recent studies report a high accuracy for unenhanced CT in the early diagnosis of acute abdominal pain in ED and advocate its systematic use in the elderly in order to expedite treatment and thus reduce morbidity and mortality, even before obtaining the serum creatinine,” wrote lead author M. Barat, department of radiology at University Hospitals Paris Nord Val-de-Seine in France, and colleagues. “This strategy could be performed to allow early ED triage in order to improve patient care. Yet, if such a strategy were to be adopted, the question of its diagnostic performance, and the added value of subsequent contrast-enhanced CT, remains unanswered.”

The authors explored data from 208 consecutive patients receiving CT imaging with both unenhanced and contrast-enhanced images from January 2012 to May 2016. All patients were 75 years old or older, and their mean age was 85.4 years old. Unenhanced imaging results were reviewed by three specialists before unenhanced and contrast-enhanced images were reviewed together.

Overall, the team found that the enhanced images “did not significantly improve the diagnostic accuracy.” Accuracy ranged from 64% to 68% for unenhanced CT and from 68% to 71% for both unenhanced and contrast-enhanced CT together. In addition, the CT scans “corrected” the ED physician’s original diagnosis 59.1% of the time before contrast and 61.2% of the time after contrast. And intra-observer agreement and inter-reader agreement were not significantly changed by including contrast-enhanced CT images in the treatment process.

“This suggests that unenhanced CT images alone could be a valuable triage modality for elderly patients admitted to ED for non-traumatic abdominal pain,” the authors wrote.

Benefits of treating patients 75 years old and older without contrast-enhanced images include a drop in total radiation dose (from 50% to 20%) and decreased chance of iodine-related renal toxicity, “which is potentially severe in the elderly, even if it has never even proven to be an independent factor of increased mortality.”  

Barat and colleagues emphasized that acquiring contrast-enhanced images can still prove helpful.

“Our results suggest a more extensive analysis of unenhanced CT images in elder patients,” they wrote. “Intravenous administration of iodinated contrast material remains of utmost importance and should not been delayed when needed. We do not advocate the use of unenhanced CT only. This is especially true when vascular anomalies need to be detected, or when bowel wall enhancement needs to be analyzed.”