The role of imaging in gastrointestinal bleed

● Upper GI bleeding UGIB: bleeding originating proximal to the Treitz ligament ● Lower GI bleeding LGIB: bleeding originating from the colon or rectum ● Suspected small-bowel bleeding: t

The Role of Imaging in Gastrointestinal

Bleeding

Introduction

Common causes of GI bleeding

● Upper gastrointestinal bleeding

○ esophageal, gastric and duodenal ulcers

○ esophagitis, gastritis, duodenitis, pancreatitis

● Small bowel bleeding

● Upper GI bleeding (UGIB): bleeding originating proximal to the Treitz ligament

● Lower GI bleeding (LGIB): bleeding originating from the colon or rectum

● Suspected small-bowel bleeding: the upper and lower GI tracts have been evaluated (typically with endoscopy) and no bleeding site has been identified

● Obscure GI bleeding: no bleeding source is found after the entire GI tract has been examined with advanced techniques

Radiologic imaging modalities of choice

Radiologic imaging modalities

● Technetium 99m scintigraphy

● Computed tomography angiography (CTA),

● Multiphase computed tomography enterography (CTE)

● Catheter angiography (CA)

● Advantage

○ Non-invasive

○ Detect slowest bleed

○ No bowel preparation required

○ Can detect intermittent bleed

● Recommendation

○ all hemodynamically stable actively bleeding LGIB

Computed tomography angiography (CTA)

● Protocols: without administration of oral contrast

○ initial non-contrast phase

■ identify pre-existing hyperdensities

○ arterial phase

■ hyperattenuating focus

○ portal venous phases

■ increase in size of hyperattenuating focus

■ slow or delayed bleed

Computed tomography angiography (CTA)

● Advantages

○ non-invasive, fast and readily available

○ identify cause even when not actively bleeding

○ can risk stratify patients

○ identify both arterial and venous bleeds and location

○ high sensitivity to detect active bleed

● Disadvantages

○ Ionizing radiation and radiation dose

○ contrast related side effects

○ intermittent bleeding may go undetected

○ non-therapeutic

○ not good for UGIB

Computed tomography angiography (CTA)

● Recommendation

○ choice of modality for all hemodynamically stable actively bleeding LGIB

○ UGIB with negative endoscopy, or endoscopy not able to identify source

Multiphase computed tomography enterography (CTE)

● Protocols

○ arterial phase (30 seconds)

○ enteric phase (50 seconds)

○ delayed phase (90–100 seconds)

○ small bowel lumen is distended with a bolus of a neutral oral contrast agent

■ allows optimal visualization of enhancement of the small bowel mucosa and wall => increase sensitivity

Multiphase computed tomography enterography (CTE)

● Advantages

○ detect source in obscure bleed

○ detect bowel pathologies even when not actively bleeding

○ evaluate bowel wall and abdominal vessels simultaneously

● Disadvantages

○ not good for acutely bleeding unstable patients

○ requires proper technique and good bowel distention

○ non-therapeutic

○ ionizating radiation

Multiphase computed tomography enterography (CTE)

● Recommendation

○ initial diagnostic modality for LGI small bowel bleed with pre-existing bowel pathology

○ In patients with negative capsule endoscopy to look for small or large bowel source

Catheter angiography (CA)

● Protocols

○ selective arterial catheterization

Catheter angiography (CA)

● Advantages

○ therapeutic interventions can also be performed

○ hemodynamically unstable patients

○ can localize exact site and cause

○ no bowel preparation required

● Disadvantages

○ embolization and vascular access site related side effects

○ ionizing radiation and contrast related side effects

○ cannot detect very slow bleed

○ poor performance in variable arterial anatomy

Catheter angiography (CA)

● Recommendation

○ LGIB: initial modality of choice for hemodynamically unstable patients or recurrent/continuous bleeding after post colonoscopic treatment

○ UGIB: acutely bleeding patients with negative endoscopy or where endoscopy could not find source

Dual-energy CT techniques

● Principles

○ acquiring both high- and low-energy datasets through a volume of tissue enables one to estimate the radiation attenuation => subtraction image

● Benefits

○ increased conspicuity of enhancing disease or extravasated contrast media

○ lower the radiation dose

ACR appropriateness criteria

Upper Gastrointestinal Bleeding

Endoscopy is the best initial modality and radiology does not play a significant role

Four situations/variants where radiologic management is useful when endoscopy:

● Reveals non-variceal arterial bleeding source: CTA and CA (hemodynamically unstable)

● Reveals non-variceal bleeding but does not identify a clear source: CTA and CA

● Negative: includes obscure UGIB CA, CTA, CTE

● Contraindicated: in CA, CTA and CT abdomen with IV contrast

Upper Gastrointestinal Bleeding

Four variant scenarios

● Active bleed and are hemodynamically stable: colonoscopy is the most appropriate In terms of radiological modalities, CTA and scintigraphy (CTA has many added advantages)

● Active bleed and are hemodynamically unstable: CA

● Rebleeding/ongoing bleeding post colonoscopic treatment for LGIB: CA

● Intermittent or obscure bleed: CTE