CT Angiography For Overt Lower Gastrointestinal Bleeding: Is Time The Missing Link

Background: CT angiography (CTA) and interventional radiology angiogram (IRA) are used in work-up of acute lower gastrointestinal bleed (LGIB). Method: Retrospective study of patients with active LGIB who underwent CTA. Divided into CTA(+) and CTA(-) groups. CTA(+) was divided into IRA(+) or IRA(-). Results: 24.1% (49/203) had CTA(+) and 75.9% (154/203) had CTA(-). No statistical significant difference was noted for hemodynamic parameters, anti-platelets and anti-coagulants, thrombocytopenia, elevated INR or blood transfusion across CTA(+) and CTA(-) groups. Median decision to test (DTT) time for CTA(+) was 98 compared to 124.5 min for CTA(-)(p= 0.039). Univariate analysis revealed DTT time as the only factor with statistically significant effect on CTA outcome. LR (pu003c 0.001) and Phi coefficient (pu003c 0.001) suggested significant difference in distribution and association between number of positive risk factors and CTA(+) respectively. In CTA(+), 81.6% (40/49) had a follow-up IRA with 32.5% (13/40) being IRA(+) while 67.5% (27/40) were IRA(-). Overall, 6.4% (13/203) patients had positive IRA. Majority of CTA were ordered by ER- 39.9% (81/203) and IM- 42.9% (87/203). For emergency department(ER)- 23.5% had CTA(+) and 3.7% had IRA(+) compared to Internal Medicine(IM) category- 25.3% had CTA(+)(p=0.78) and 5.7% had IRA(+)(p=0.53). 57.9% patients in CTA(+) had a follow-up IRA in ER category in contrast to 95.5% in IM (p=0.0038). Conclusion: One in sixteen patient benefits from CTA. IM did better than ER in selecting patients for CTA. Number of positive risk factors correlates with probability of CTA(+). Decreasing DTT time may be the key to improve diagnostic yield.