Predictors of positive CT mesenteric angiogram in patients with lower gastrointestinal bleeding.

Abstract

Purpose/Background: Lower gastrointestinal bleeding (LGIB) is a challenging presentation prevalent in a comorbid, elderly population. CT mesenteric angiography (CTMA) can localise the site of haemorrhage and provide a target for angioembolisation, although it may not reliably demonstrate extravasation, given the intermittent nature of LGIB. The aim of this study is to identify objective factors predicting positive CTMA. Methods/Interventions: We conducted a retrospective audit of patients undergoing CTMA for LGIB at Monash Health from 2011 to 2019. 849 CTMA scans were included. Baseline patient characteristics included age, recent bowel surgery/endoscopic intervention, known bowel malignancy, anticoagulant/antiplatelet use, duration of symptoms, vital signs, blood transfusions in the past 24 hours, recent haemoglobin levels, platelet count, coagulation studies, and creatinine levels. Significant factors from univariate analysis were then entered into a multivariate binary logistic regression model. Results/Outcomes: CTMA had a 20.7% positive rate for active extravasation (n = 176). The final multivariate model was statistically significant (p < 0.001) and consisted of: bowel surgery/endoscopic intervention within the past 14 days (OR = 2.15), use of antiplatelet agents (OR = 2.03), blood transfusion greater than 3 units per 24 hours (OR = 1.79), systolic blood pressure less than 100 mmHg (OR = 1.56), and heart rate greater than 100 beats per minute (OR = 1.52). Conclusion/Discussion: Our findings suggest that more judicious selection of patients with LGIB for CTMA may be possible. Prioritisation of patients with haemodynamic instability, significant blood transfusion requirement, recent intervention or surgery, or on antiplatelet agents, will likely improve yield of CTMA and limit unnecessary resource use, contrast load and radiation exposure.