CT-angiography in acute bleeding: Is a non-enhanced scan necessary?

In clinical routine CT-angiography is frequently used to detect hemorrhage and to locate its source. Many centers use a triple phase protocol consisting of non-contrast, arterial and portal venous phase scan. The aim of this study was to clarify the added value of the non-contrast CT scan in detection of hemorrhage and to provide evidence for or against its usage.

We retrospectively included all patients between 2014 and 2020 who underwent triphasic CT angiography for suspected bleeding and interventional angiography within 6 h of CT confirming bleeding. Two experienced observers re-evaluated all CT scans and established consensus on whether the bleeding could confidently be detected without the non-enhanced CT scan. Additionally, we recorded data on radiation exposure.

We included 75 patients (44 male, 31 female, median age 64 years) in the final dataset. Of all bleedings 33 (43 %) were GI bleedings. After consensus reading, non-enhanced CT scan was deemed helpful in only 3 cases (5.2 %) with all of these being GI bleeding. Non-enhanced series contributed substantially to the overall radiation exposure (mean DLP_{non contrast} 927.9 mGy*cm, mean DLP_arterial 631.3 mGy*cm, mean DLP_{portal venous} 915.0 mGy*cm).

Our results suggest that in the vast majority of cases non-contrast CT is not necessary to detect hemorrhage. Omission of non-enhanced CT scans results in relevant dose reduction. However, in few cases non-contrast scan can be helpful to exclude false positive findings in particular in suspected gastrointestinal bleeding.