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

Abstract

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 (p< 0.001) and Phi coefficient (p< 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.