IMPORTANCE Optimizing the nature and sequence of diagnostic imaging when managing lower gastrointestinal hemorrhage may reduce subsequent morbidity and mortality. OBJECTIVES To determine if preceding visceral arteriography with computed tomographic angiography (CTA) in acute lower gastrointestinal hemorrhage increases hemorrhage identification and localization and to determine if CTA was superior to nuclear scintigraphy when used as a pre-angiogram test. DESIGN, SETTING, AND PARTICIPANTS Analysiswas conducted of prospectively acquired data from an interventional radiology database and of individual electronic medical records from an academic tertiary medical center. On January 1, 2009, a new, evidence-based, institutional protocol that formally incorporated CTA to manage acute lower gastrointestinal hemorrhage was launched after multidisciplinary consultation. All records of patients who underwent visceral angiography (VA) for acute lower gastrointestinal hemorrhage from January 1, 2005, to December 31, 2012, were evaluated. EXPOSURES Imaging, procedural, and operative details were abstracted from the medical records of all patients who underwent VA for lower gastrointestinal hemorrhage. MAIN OUTCOMES AND MEASURES Visceral angiography results and efficacywere compared in patients before and after protocol implementation and compared based on which imaging method was used prior to angiography. RESULTS A total of 161 angiographic procedures were performed during the study period (78 before and 83 after protocol implementation). Use of CTA increased from 3.8% to 56.6%, and use of nuclear scintigraphy decreased from 83.3%to 50.6%following protocol implementation (P < .001). Preceding angiography with CTA resulted in similar angiography contrast administration (mean [SD] amount for CTA prior to VA, 135  vs 160  mL; P = .18) and fluoroscopy time (mean [SD], 26.3 [16.8] vs 32.2 [34.9] minutes; P = .34). Although nuclear scintigraphy and CTA had similar sensitivity and specificity, localization of hemorrhage site by CTA was more precise and consistent with angiography findings. As a pre-angiography test, compared with nuclear scintigraphy, CTA reduced overall the number of imaging studies required (mean [SD] number per patient admission, 2.1 [0.3] vs 2.5 [0.8]; P = .005) and resulted in administration of more overall contrast (mean [SD], 220  vs 130  mL; P < .001) without worsening renal function. CONCLUSIONS AND RELEVANCE Preceding VA with a diagnostic study improves positive localization of the site of lower gastrointestinal hemorrhage compared with VA alone. Increasing the use of CTA for pre-angiography imagingmay reduce overall imaging studies while appearing to increase positive yield at VA. Computed tomographic angiography can be used as part of a lower intestinal hemorrhage management algorithm and does not appear to worsen renal function despite the additional contrast load.
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