S668 Clinical Predictors of a Positive CT Angiogram Study Used for the Evaluation of Acute Gastrointestinal Hemorrhage

Abstract

Introduction: Acute gastrointestinal (GI) bleeding is one of the leading causes of emergency department visits and hospital admissions. CT angiography (CTA) has had an expanding role in the evaluation of acute GI bleeding because it is rapidly performed, widely available, reasonably sensitive and provides precise localization when positive. We attempted to identify patient and clinical characteristics that predict CTA results in order to help guide the utilization of this modality in patients with acute GI bleeding. Methods: In this retrospective study, we analyzed all CTAs performed for the evaluation of GI bleeding in the Duke University healthcare system between October 2019 and March 2020. We captured patient characteristics including age, sex, vital signs, hemoglobin, platelets, PT/INR and anticoagulation status. We grouped study indication into three categories: upper GI bleeding (hematemesis or coffee ground emesis); small bowel bleeding (melena or dark stool); and lower GI bleeding (hematochezia or bright red blood per rectum) as indicated by the ordering provider. Chi-square, Wilcoxon, t-test, and multivariate logistic regression were used to describe and assess the relationship between patient characteristics and study outcomes (Table 1). Results: A total of 317 studies were performed between October 2019 and March 2020. Forty-three patients (13.6%) had a CTA positive for active bleeding. Multivariable logistic regression showed that after controlling for age, MAP and indication, only a hemoglobin drop from baseline was significantly associated with a positive CTA. For each 1 unit increase in hemoglobin drop, the odds of a positive CT increased by 1.17 (OR 1.17 95% CI 1.00 – 1.36, p = 0.04). Age (OR 1.02 95% CI 0.99 – 1.04, p = 0.06) and lower GI bleeding (OR 2.09 95% CI 0.94 - 4.64, p = 0.07) approached statistical significance. Conclusion: In patients who present to the hospital with GI bleeding, those with a drop in hemoglobin from baseline are most likely to have active bleeding found on CTA. Older age and suspected lower GI bleeding are also likely to be valuable predictors of a positive CTA. In the absence of these factors, CTA is less likely to be clinically useful.Table 1.: Mortality in post-bariatric surgery patients that had UGIB (OR).