Optimizing Indications and Diagnostic Performance of Computed Tomography Angiography in Acute Gastrointestinal Bleeding: A Large Cohort Study.

BACKGROUND AND AIMS: The diagnostic accuracy of computed tomography angiography (CTA) and its appropriate clinical indications remain unclear. We aimed to assess the diagnostic performance of CTA and identify clinical predictors to determine the optimal clinical indications for its use in patients with acute gastrointestinal (GI) bleeding. METHODS: This large cohort study included patients who underwent CTA for suspected acute GI bleeding in Korea between October 2011 and December 2023. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of CTA were assessed. Multivariate analysis was conducted to identify the predictors of positive CTA findings, and a predictive nomogram was developed and validated. RESULTS: Of the 5,525 patients identified, 1,770 were included in the final analysis. CTA demonstrated low sensitivity (44.9%) and PPV (52.4%), with relatively high specificity (88.3%) and NPV (84.9%). Multivariate analysis identified male sex, use of antithrombotic agents, low hemoglobin level (<9.6 g/dL), elevated blood urea nitrogen level (≥29.9 mg/dL), hemodynamic instability, and presentation with hematemesis or hematochezia as independent predictors of positive CTA findings. A nomogram incorporating these variables showed good discrimination. The selective application of CTA based on clinical risk factors improved diagnostic sensitivity (47.3% at predicted probability ≥0.1, 56.5% at ≥0.2, and 69.5% at ≥0.3; all P < 0.001). CONCLUSIONS: Although CTA may be unsuitable as an initial diagnostic modality for acute GI bleeding, its selective use-guided by a clinical prediction model-can help identify patients most likely to benefit, thereby reducing inappropriate use and improving the diagnostic yield of CTA.