CT GI Bleed Protocol — Dictation, Appropriateness, and Dose for Residents
Stat from the ER. A patient with hematochezia is hemodynamically unstable, requiring multiple units of packed red blood cells. The GI team can’t get a scope down fast enough to find the source. Interventional Radiology is on the phone, asking you one question: “Where’s the bleed?” This is the exact scenario where the triple-phase CT Angiography (CTA) for GI bleed becomes the most important study on your list. Your job is to find that tiny jet of contrast extravasation and give the IR team a precise roadmap for embolization.
When I was a resident, the pressure on these reads was intense. You’re not just describing anatomy; you’re directing a potentially life-saving procedure. Getting the location right—and communicating it clearly—is everything. This guide will walk you through a structured approach to dictating these studies, ensuring you hit every key point your attending and the IR team need to see. For more guides and tools, check out our free residents and fellows resource hub.
What a CT Angiography for GI Bleed Covers and What Attendings Look For
The primary goal of a CTA for a GI bleed is to answer a few critical questions with speed and precision. It’s significantly faster and more anatomically specific than a tagged RBC scan, making it the workhorse for acute, brisk bleeding. Your attending isn’t just looking for a positive or negative read; they expect a comprehensive evaluation that guides the next step in management.
Your report should definitively answer:
- Is there active bleeding? The key finding is active contrast extravasation into the bowel lumen.
- Where is the source? Provide a precise location (e.g., “distal transverse colon, 10 cm proximal to the splenic flexure”). This is the roadmap for the interventionalist.
- Is the bleed arterial or venous? Arterial extravasation will be densest on the arterial phase and will pool or expand on the portal venous phase.
- What is the underlying cause? Look for diverticulosis, an enhancing mass, an arteriovenous malformation (AVM), angiodysplasia, or signs of vasculitis.
- Is the patient a candidate for embolization? Note the accessibility of the feeding vessel and any anatomic variants.
Radiology Report Template for CT Angiography for GI Bleed (Triple-Phase)
This template provides a solid foundation. Remember to tailor the findings to the specific case. The most critical mistake you can avoid is allowing the patient to receive positive oral contrast—it will completely obscure any potential bleed.
Technique
Multi-phase CT of the abdomen and pelvis was performed without oral contrast and with intravenous contrast. Non-contrast, arterial, and portal venous phase images were acquired through the abdomen and pelvis. IV contrast: [e.g., 120 mL of Isovue 370].
Findings
COMPARISON: [Date of prior study]
ACTIVE HEMORRHAGE: [Present/Absent]. If present, describe the location, phase of maximal conspicuity, and underlying cause. Example: “Active arterial contrast extravasation is identified within the lumen of the mid-transverse colon on the arterial phase, with subsequent pooling and expansion on the portal venous phase. This arises from a small diverticulum.”
BOWEL: No evidence of active hemorrhage. No bowel wall thickening, obstruction, or ischemia. Normal appendix. Diverticulosis is noted in the [e.g., sigmoid colon].
VASCULATURE: Patent celiac, superior mesenteric, and inferior mesenteric arteries. Patent aorta and IVC. Patent portal and hepatic veins.
LIVER, GALLBLADDER, BILIARY TREE: No focal hepatic lesion. No intra- or extrahepatic biliary ductal dilatation. Gallbladder is unremarkable.
SPLEEN, PANCREAS, ADRENAL GLANDS: Unremarkable.
KIDNEYS AND URETERS: No hydronephrosis or suspicious renal mass.
PELVIC ORGANS: Unremarkable.
LYMPH NODES: No pathologic lymphadenopathy.
BONES AND SOFT TISSUES: No acute osseous abnormality.
LUNG BASES: Clear.
Impression
1. [No evidence of / Evidence of] active arterial hemorrhage.
2. If positive: Active arterial extravasation within the [e.g., transverse colon] consistent with acute gastrointestinal hemorrhage, likely secondary to diverticular disease. The primary feeding vessel appears to be a branch of the [e.g., middle colic artery]. Please correlate clinically. Interventional Radiology consultation may be warranted.
Free Template Sources
Building a personal library of high-quality templates is a key part of residency. While the template above is a great starting point, two great free repositories exist for finding templates across every subspecialty. These are excellent resources maintained by the radiology community.
- RadReport.org: Curated by the RSNA, this is a comprehensive library of peer-reviewed, structured reporting templates.
- Radiology Templates (AU): An excellent, user-friendly site maintained by Australian radiologists with a wide variety of practical templates.
The Next-Level Move: AI-Assisted Structured Reporting
Dictating a complex positive finding, like a GI bleed, can be messy. You’re focused on describing the location, the vessel, the underlying cause—and then you have to clean it all up into a perfectly structured report with a clean impression. This is where modern tools can streamline your workflow without replacing your clinical judgment.
Instead of meticulously structuring every line, you can dictate the positive findings in free form—”active arterial extravasation in the mid transverse colon from a diverticulum, looks like it’s coming off a branch of the middle colic artery”—and let an AI tool handle the rest. The GigHz Precision AI reporting assistant is designed for this exact task. It takes your free-form dictation of positive findings and generates a clean, structured report based on pre-loaded ACR and SIR templates. It helps ensure your reports are consistent, complete, and ready for your attending to sign, letting you focus on the diagnosis, not the formatting.
When Should You Order a CT Angiography for GI Bleed? ACR Appropriateness Criteria
The decision to order a CTA for GI bleed is typically made in the setting of an acute, hemodynamically significant bleed. The American College of Radiology (ACR) provides guidance on this topic to ensure the right test is ordered for the right clinical scenario.
According to the ACR Appropriateness Criteria for Radiologic Management of Lower Gastrointestinal Tract Bleeding, a multiphase CT Angiography of the abdomen and pelvis is Usually Appropriate for the initial imaging of a patient with an active lower GI bleed. It provides the necessary anatomical detail to localize the source and plan for intervention.
Key alternatives and their roles include:
- Tagged RBC Scintigraphy: This nuclear medicine study is more sensitive for very slow or intermittent bleeding (down to ~0.1 mL/min), but it lacks the anatomic precision of CTA and takes much longer to perform. It’s a better choice when bleeding is slow and CTA is negative.
- Catheter Angiography: This is the gold standard for both diagnosis and treatment, as embolization can be performed in the same setting. However, it is invasive and typically reserved for cases where a bleeding source has been localized on CTA or when the patient is too unstable for the CT scanner.
- Endoscopy/Colonoscopy: These are first-line for stable upper and lower GI bleeds, respectively, as they offer direct visualization and therapeutic capability. CTA is typically used when endoscopy fails to localize a source or cannot be performed.
How Much Radiation Does a Triple-Phase CT for GI Bleed Deliver?
A triple-phase CTA for GI bleed is a higher-dose study due to the multiple acquisitions required to characterize the bleed. The estimated effective dose is typically in the range of 15-30 mSv. This is a significant dose, equivalent to several years of natural background radiation, and its use should be justified by the clinical urgency.
To put this in perspective:
| Imaging Study | Typical Effective Dose (mSv) |
|---|---|
| Chest X-ray (PA view) | 0.02 mSv |
| Annual Background Radiation (US) | ~3 mSv |
| CT Abdomen/Pelvis (single phase) | ~10 mSv |
| CTA GI Bleed (3-4 phases) | 15-30 mSv |
The protocol is optimized to answer a life-threatening question, and the benefit of localizing a massive bleed far outweighs the radiation risk in this acute setting. Dose reduction techniques like automated tube current modulation are standard, but the fundamental need for multiple phases dictates the overall dose. This study is not used for screening or for low-suspicion cases.
CT Angiography for GI Bleed Imaging Protocol — Phases, Contrast, and Reconstructions
A successful GI bleed protocol hinges on precise timing and the complete omission of oral contrast. The goal is to create a high-contrast environment where extravasated iodinated contrast in the bowel lumen is the only bright thing that appears after the non-contrast phase. The protocol uses a non-contrast baseline, a fast arterial phase to catch the bleed, and a portal venous phase to confirm pooling and evaluate underlying pathology.
Below is a typical protocol structure:
| Phase | Contrast | Scan Timing | Key Parameters |
|---|---|---|---|
| Non-contrast | None | N/A | 120 kVp, 5mm axial / 3mm coronal slices. Establishes baseline density. |
| Arterial | 100-130 mL @ 4-5 mL/s | Bolus tracking on aorta (150 HU threshold + 5s delay) | 100 kVp, 1mm thin slices for high-res reconstructions. Catches the active bleed. |
| Portal Venous | Same bolus | ~70 seconds post-injection | 120 kVp, 5mm axial / 3mm coronal slices. Shows pooling of extravasated blood and characterizes underlying lesions. |
| Delayed (Optional) | Same bolus | 3-5 minutes post-injection | 120 kVp. Used when arterial phase is equivocal. Continued pooling confirms extravasation. |
Common protocol pitfalls: The single most common error is the administration of positive oral contrast, which renders the study non-diagnostic. The second is improper bolus timing, which can miss the peak arterial enhancement of a small bleed. An optional delayed phase can be a lifesaver when the arterial phase is ambiguous; if a focus of enhancement pools and expands, it’s a bleed. If it washes out, it was likely just a vessel or enhancing mucosa.
The 3-Months-Free Offer for Residents and Fellows
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We built GigHz Precision AI to help you look like a rockstar on your reports. You can dictate your positive findings in free form, and the AI will generate a perfectly structured report using ACR and SIR templates, with the appropriate clinical decision support firing automatically. This lets you focus on the medicine, not the clerical work of formatting reports.
All we ask in return is your feedback so we can keep improving the product for trainees. The signup process is simple, with no credit card and no long forms. To get started, just provide three items:
- Your PGY year (e.g., PGY-2, PGY-4)
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- Your training program / hospital name
Ready to give it a try? Apply for the residents free-access program and we’ll get you set up.
Free GigHz Tools That Pair With This Article
Three free tools that complement the material above:
- ACR Appropriateness Criteria Lookup — Type an indication or clinical scenario in plain language and get the imaging studies the ACR rates for it, with adult and pediatric radiation levels. Built directly from 297 ACR topics, 1,336 clinical variants, and 15,823 procedure ratings.
- GigHz Imaging Protocol Library — A searchable library of 131 imaging protocols with the physics specs surfaced and the matching ACR Appropriateness Criteria alongside. Plain-English narratives readable in 60 seconds, organized by modality.
- GigHz Radiation Dose Calculator — Pick the imaging studies a patient has had and see total dose in millisieverts (mSv) with comparisons to natural background radiation, transatlantic flights, and chest X-rays. Useful for shared decision-making.
Frequently Asked Questions
Is GigHz Precision AI HIPAA-compliant?
Yes. The platform is designed for de-identified workflows by default. It does not require or store Patient Health Information (PHI) to function. All processing is done in a secure, HIPAA-compliant environment.
Do I need my hospital’s IT department to set it up?
No. GigHz Precision AI is a secure, browser-based tool. There is no software to install. It works on any computer, including the call-room PC or your personal iPad, without needing IT approval or integration.
How does this work with PowerScribe or other dictation systems?
It works alongside your existing dictation system. You can dictate your findings as you normally would, then use the AI assistant to structure the report. The final, clean text can be easily copied and pasted into your PACS/RIS.
Can I use this on my phone or iPad?
Yes, the platform is fully responsive and works on modern web browsers across desktops, tablets, and mobile devices, making it accessible whether you’re at a workstation or on the go.
Can I customize the templates?
Yes. While the system comes pre-loaded with standard templates from societies like the ACR and SIR, you can create, modify, and save your own templates to match your personal or institutional preferences.
What happens after my residency or fellowship ends?
We offer continuity plans for graduating trainees who want to continue using the platform in their practice. Your free access runs for the specified period, after which you can choose to transition to a paid plan or discontinue use.
Reviewed by Pouyan Golshani, MD, Interventional Radiologist — May 7, 2026
