From the Guidelines
For painless rectal bleeding, CT angiography (CTA) is the best CT option, as it can detect bleeding rates as slow as 0.3 mL/min and has a sensitivity and specificity of 85% and 92%, respectively, for the diagnosis of active gastrointestinal bleeding (GIB) 1.
Key Considerations
- CTA uses a triphasic approach, including non-contrast, arterial, and venous phases, to identify the bleeding source 1.
- The procedure involves IV contrast and can help detect potential sources of bleeding such as polyps, tumors, diverticular disease, or vascular abnormalities.
- CTA is particularly valuable when colonoscopy is contraindicated or incomplete, or when extraluminal causes of bleeding are suspected.
Comparison with Other Options
- Contrast-enhanced CT colonography (virtual colonoscopy) is also an option, but CTA is preferred when active bleeding is suspected 1.
- Conventional colonoscopy remains the gold standard diagnostic procedure, offering superior sensitivity for detecting mucosal abnormalities and allowing for immediate biopsy and potential treatment.
Clinical Application
- CTA can lead to faster triage of patients toward definitive treatment by angiography, and its use as the first test can lead to faster triage of patients in the emergency room compared with endoscopy for GI bleed 1.
- The choice of CT protocol, including the use of oral contrast and multiphasic acquisition, should be guided by the clinical suspicion of GIB and the availability of CT technology 1.
From the Research
CT Scan Options for Painless Rectal Bleeding
- The use of contrast-enhanced CT scans is supported by studies for the diagnosis of rectal bleeding, including painless rectal bleeding 2.
- A contrast-enhanced CT scan of the abdomen and pelvis can help confirm the diagnosis of certain conditions, such as cavernous hemangioma, which can cause rectal bleeding 2.
- The administration of intravenous (IV) contrast for CT abdomen and pelvis examinations has been shown to improve the detection of urgent and non-urgent pathology compared to non-contrast CT scans 3.
- The use of IV contrast-enhanced CT scans can also help avoid the need for repeat CT exams within a short period, such as 72 hours, by providing more accurate and detailed information on the first scan 3.
Key Findings
- Contrast-enhanced CT scans are associated with increased detection of urgent findings compared to non-contrast CT scans 3.
- The use of IV contrast can better characterize both urgent and non-urgent findings on CT scans 3.
- Adherence to American College of Radiology (ACR) appropriateness criteria for IV contrast administration can increase the detection of urgent pathology on the first CT scan 3.