Helical CT in the diagnosis of acute lower gastrointestinal haemorrhage.

INTRODUCTION: A pilot study to evaluate helical computer tomography (CT) as a diagnostic tool for acute lower gastrointestinal tract (GIT) bleeding. CT was compared to conventional angiography (CA) and colonoscopy for the diagnosis and detection of bleeding site in suspected cases of acute lower GIT bleeding.

METHODS: Seven patients presenting with acute lower GIT bleeding, between June and November 2002, underwent CT examinations. All of these seven patients underwent CA following CT. Emergency colonoscopies were performed on five patients investigated with both CT and CA. Median delay from the most recent episode of hematochezia to CT was two and a half hours, to CA was 3h, and to colonoscopy was 4h. None of the patients underwent nuclear medicine (NM) bleeding studies.

RESULTS: Haemoglobin drop in all patients was greater than 15 g/L in the first 24h of presentation. The mean age was 68.86 years (range, 49-83 years). Comparing CT and CA, there were four concordant and three discordant results. Both modalities had concordant findings of two active bleeding sites, one non-bleeding rectal tumour, and one negative case result. In three patients, the source of bleeding was found on CT whereas CA was negative. Emergency colonoscopies performed in all of these three patients confirmed blood in the colon/ileum.

CONCLUSION: Early experience suggests that CT is a safe, convenient and accurate diagnostic tool for acute lower GIT haemorrhage. It raises questions regarding the sensitivity of CA. A new management algorithm for acute lower GIT haemorrhage using CT as the pre-CA screening tool is being proposed based on the preliminary findings. Positive CT will allow directed therapeutic angiography, while negative CT will triage patients into alternative management pathways.