The role of imaging in gastrointestinal bleed

The Role of Imaging in Gastrointestinal
Bleeding


Introduction


Common causes of GI bleeding

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Upper gastrointestinal bleeding

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Lower gastrointestinal bleeding

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esophageal, gastric and duodenal ulcers
esophagitis, gastritis, duodenitis, pancreatitis
neoplasms
vascular malformations
varices

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diverticulosis
post-polypectomy bleeding
ischemic colitis
colorectal polyps/neoplasms
inflammatory bowel disease
anorectal conditions


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Small bowel bleeding

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neoplasia
meckel’s diverticulum
polyposis syndromes
Angioectasia
NSAID ulcers

Nomenclature

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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

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Technetium 99m scintigraphy
Computed tomography angiography (CTA),
Multiphase computed tomography enterography (CTE)
Catheter angiography (CA)

Scintigraphy

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Protocol

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labeling the RBCs
intravascular injection
dynamic acquisition



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Advantage

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Disadvantages

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Non-invasive

Detect slowest bleed
No bowel preparation required
Can detect intermittent bleed

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Ionizing radiation and radiation dose
Non-therapeut
Not good for UGIB


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Recommendation

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all hemodynamically stable actively bleeding LGIB


Computed tomography angiography (CTA)

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Protocols: without administration of oral contrast

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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

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Computed tomography angiography (CTA)

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Advantages

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Disadvantages

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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

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Ionizing radiation and radiation dose
contrast related side effects
intermittent bleeding may go undetected
non-therapeutic
not good for UGIB


Computed tomography angiography (CTA)

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Recommendation

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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)

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Protocols

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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

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Multiphase computed tomography enterography (CTE)

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Advantages

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Disadvantages

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detect source in obscure bleed
detect bowel pathologies even when not actively bleeding
evaluate bowel wall and abdominal vessels simultaneously

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not good for acutely bleeding unstable patients
requires proper technique and good bowel distention
non-therapeutic
ionizating radiation


Multiphase computed tomography enterography (CTE)

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Recommendation

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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)

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Protocols

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selective arterial catheterization




Catheter angiography (CA)

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Advantages

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Disadvantages

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therapeutic interventions can also be performed
hemodynamically unstable patients
can localize exact site and cause
no bowel preparation required

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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)

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Recommendation

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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