Role of urgent contrast-enhanced multidetector computed tomography for acute lower gastrointestinal bleeding in patients undergoing early colonoscopy

Background The clinical significance of performing computed tomography (CT) for acute lower gastrointestinal bleeding (LGIB) remains unknown. This study aimed to evaluate the role of urgent CT in acute LGIB settings. Methods The cohort comprised 223 patients emergently hospitalized for LGIB who underwent early colonoscopy within 24 h of arriving at the hospital, including 126 who underwent CT within 3 h of arrival. We compared the bleeding source rate between two strategies: early colonoscopy following urgent CT or early colonoscopy alone. Results No significant differences in age, sex, comorbidities, vital signs, or laboratory data were observed between the strategies. The detection rate was higher with colonoscopy following CT for vascular lesions (35.7 vs. 20.6 %, p = 0.01), leading to more endoscopic therapies (34.9 vs. 13.4 %, p < 0.01). Of the 126 who underwent colonoscopy following CT, 26 (20.6 %) had extravasation and 34 (27.0 %) had nonvascular findings. The sensitivity and specificity of CT extravasation and nonvascular findings for predicting vascular lesions and inflammation or tumors were 37.8 and 88.9 and 81.3 and 80.9 %, respectively. A high kappa agreement (0.83, p < 0.01) for active bleeding locations was found between CT and subsequent colonoscopy. There were no cases of contrast-induced nephropathy after 1 week of CT. Conclusions Urgent CT before colonoscopy had about 15 % additional value for detecting vascular lesion compared to colonoscopy alone and thus enabled subsequent endoscopic therapies. Contrast-enhanced CT in acute LGIB settings was safe and correctly identified the presence and location of active bleeding, as well as severe inflammation or tumor stenosis, facilitating decision making.