Why order a stat CT (Computed Tomography) Angiography for Gastrointestinal (GI) bleed?

From the Guidelines

A stat CT angiography (CTA) should be ordered for a GI bleed when rapid identification of the bleeding source is needed, particularly in cases of active, severe hemorrhage or hemodynamic instability, as recommended by the most recent guidelines 1. This imaging modality is especially valuable for patients with hemodynamic instability or when endoscopy has failed to identify the bleeding source. The procedure involves intravenous contrast administration followed by rapid CT scanning, which can detect active extravasation of contrast into the bowel lumen at bleeding rates as low as 0.3 mL/min. Some key points to consider when ordering a stat CT angiography for GI bleed include:

• CTA offers several advantages including wide availability in most hospitals, rapid acquisition time (typically under 5 minutes), and the ability to visualize the entire GI tract without the need for bowel preparation 1.
• It can identify various causes of bleeding such as angiodysplasia, tumors, or vascular malformations, and helps guide subsequent interventions like endoscopic therapy or angiographic embolization 1.
• The main limitations include radiation exposure, potential contrast-induced nephropathy in patients with renal impairment, and decreased sensitivity for intermittent or slow bleeding 1.
• For optimal results, the study should be performed during active bleeding, making timing crucial for diagnostic accuracy 1.
• According to the British Society of Gastroenterology guidelines, if a patient is haemodynamically unstable or has a shock index (heart rate/systolic BP) of >1 after initial resuscitation and/or active bleeding is suspected, CT angiography provides the fastest and least invasive means to localise the site of blood loss before planning endoscopic or radiological therapy 1.

From the Research

Reasons for Ordering a Stat CT Angio for GI Bleed

• A stat CT angio can be ordered for GI bleed to rapidly diagnose active bleeding and nonbleeding bowel disease, as it can provide diagnostic information to guide management 2, 3.
• CT angiography (CTA) is a promising initial test for acute GI bleeding, as it is universally available and can be performed rapidly 2.
• CTA can aid in identifying the location and cause of bleeding, and is an important complementary tool to endoscopy, nuclear medicine, and angiography in evaluating patients with GI bleeding 4.
• In patients requiring conventional angiography for GI bleeding, CT angiography results in a faster time to angiography than tagged RBC scan, which can help reduce morbidity and mortality 5.
• The use of CT for evaluation of acute GI bleeding is gaining popularity due to its ability to rapidly diagnose active bleeding and nonbleeding bowel disease, and its potential to guide the choice of subsequent therapy 3.

Key Benefits of CT Angio for GI Bleed

• Rapid diagnosis of active bleeding and nonbleeding bowel disease
• Identification of the location and cause of bleeding
• Complementary tool to endoscopy, nuclear medicine, and angiography
• Faster time to angiography compared to tagged RBC scan
• Potential to guide the choice of subsequent therapy

Studies Supporting the Use of CT Angio for GI Bleed

• 2: CT angiography for acute gastrointestinal bleeding: what the radiologist needs to know
• 4: Gastrointestinal Bleeding at CT Angiography and CT Enterography: Imaging Atlas and Glossary of Terms
• 5: Time to conventional angiography in gastrointestinal bleeding: CT angiography compared to tagged RBC scan
• 3: CT for Evaluation of Acute Gastrointestinal Bleeding