Table 7.

Frequent vascular and non-vascular causes of LGIB: clinical presentation and CT findings.

	Clinical Presentation	CT Findings
Diverticulosis (Figure 33)	Asymptomatic or bleeding.	Protruding sacs where the vessels pass through the muscularis layer, between the mesenteric and antimesenteric taenia.
Angiodysplasia (Figure 5 and Figure 34)	Asymptomatic or bleeding.	Small hyperdense nodules within the intestinal wall, best defined in the portal phase of the study.
Arterio-venous Malformation (Figure 17)	Haematochezia-rectorrhagia.	Vascular nidus with early opacification of the veins in the arterial phase.
Dieulafoy’s Lesion	Asymptomatic or bleeding.	Abnormally enlarged submucosal vessel, which may appear tortuous, linear or as a non-specific “blush” of contrast medium at the mucosal/submucosal level.
Rectal Varices and Haemorrhoids (Figure 35)	Pain and/or bleeding.	Dilated veins with possible bleeding visible in the portal phase; rectal varices are located proximal to the linea dentata while haemorrhoids are located in the anus.
Colorectal Cancer/Polyps (Figure 6, Figure 36, Figure 37 and Figure 38)	Bowel obstruction with or without bleeding.	Adenocarcinoma: irregular wall thickening with or without stenosis [25]; Polyps: mass-forming protrusions in the intestinal lumen with vascularised peduncle.
Inflammatory Bowel Disease (Figure 39 and Figure 40)	Haematochezia-rectorrhagia.	Acute: thickening of the walls, engorgement of the adjacent vasa recta, hyperaemia of the mucosa and infiltration of perirectal fat. Chronic: the colon and rectum are narrowed and shortened, without haustra, and with proliferation of the perirectal fat.
Colitis (Figure 41)	It depends on the aetiology.	Non-specific but associated with medical history, the clinical history and location of the lesions, it may be useful for diagnostic purposes.
[26,30]