Table 6.

Frequent vascular and non-vascular causes of SBB/MGIB: clinical presentation and CT findings.

NON-VASCULAR CAUSES
	Clinical Presentation	CT Findings
Tumour (Figure 29)	Asymptomatic or bleeding.	Irregular wall thickening with foci of active bleeding.
GIST	Asymptomatic or bleeding.	Soft tissue density mass with variable areas of necrosis. They are usually highly vascularised and the enhancement of the lesion may vary from homogeneous to peripheral and irregular depending on the lesion dimension and grade of malignancy.
Ulcer	Obscure bleeding.	Thickening of the walls and fluid collections, extravasation of contrast medium. CT is poorly sensitive in the detection of superficial lesions.
Meckel’s Diverticulum (Figure 30)	Asymptomatic or, rarely, massive gastrointestinal bleeding.	A diverticulum with fluid or air content originating from the antimesenteric side of the distal ileum.
Jejunal-Ileal Diverticulum	Asymptomatic or, rarely, massive gastrointestinal bleeding.	Similar to Meckel’s diverticulum.
Aorto-Enteric Fistula (Figure 31)	Bleeding in a patient with a history of surgery for aortic aneurysm.	A connection between the aorta and the intestinal lumen. Absence of adipose cleavage planes.
Haemobilia (Figure 32)	Melaena, haematemesis, biliary colic, jaundice, or massive bleeding in a patient with a history of blunt or iatrogenic abdominal trauma.	Presence of blood in the gallbladder and biliary tree.
Pancreatic Haemorrhage	Intermittent epigastric pain in the abdomen, gastrointestinal bleeding (melaena, haematemesis, haematochezia) and raised serum amylase.	Pseudoaneurysm or pseudocyst with signs of active bleeding, associated with the finding of hyperdense material in the pancreatic ducts.
VASCULAR CAUSES
Angiodysplasia (Figure 11)	Obscure bleeding.	Abnormally dilated, tortuous, thin-walled vessels involving small capillaries, veins and arteries.
Telangiectasia (Figure 18)	Iron deficiency anaemia with recurrent gastrointestinal bleeding.	Punctate area of enhancement with direct connections between arteries and veins.
Dieulafoy’s Lesion	Obscure bleeding.	Abnormal arteries typically protruding through a small mucosal defect ranging in size from 2 to 5 mm.
Venous Lesion	Obscure bleeding.	Varices may be visible in the enteric phase and become more intense in the late phase, with progressive filling of the mesenteric-systemic collateral veins.
Venous Angioma	Obscure bleeding.	Globular enhancement. Sometimes, phleboliths within the lesions, which are more visible in the arterial phase.
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