Gastrointestinal Imaging

Diverticular haemorrhage, colon

bleeding originating in a diverticulum of the colon. It may cause severe and life-threatening haemorrhage. It is the most common cause of lower gastrointestinal bleeding in elderly people and will occur in 35% of patients with diverticulosis.

Haemorrhage occurs more frequently from a diverticulum of the right colon (Fig.1). The mechanism for the haemorrhage is presumed to be focal mucosal ulceration at the dome of the diverticulum by some traumatic factor, possibly inspissated faeces, causing erosion of the vasa recta. The wider neck and dome of the diverticula of the right colon may expose the vasa recta over a greater length and explains the higher frequency of bleeding from the right colon.

Although scintigraphy with Technetium 99m sulphur colloid or with Technetium 99m labelled red blood cell may identify a suspected area of bleeding, angiography is the preferred method. It will in most instances allow a distinct visualization of the bleeding site (Fig. 1).

Subselective catheterization of branches of the superior mesenteric artery, which is technically more difficult in elderly patients, is not required in most instances in order to demonstrate the extravasation of the contrast medium. Selective vasopressin infusion will stop the bleeding in most patients. Failures may be due to atherosclerotic vessels that respond less well to vasopressin. It is advisable to complete the infusion of vasopressin by embolization. This approach will allow performing of subsequent selective surgery when the general condition of the patient has stabilized.

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Fig.1

Diverticular haemorrhage in the ascending colon. Selective superior mesenteric arteriography. a. Arterial phase and b. capillary phase. Note the extravasation of contrast medium (arrow) from the bleeding diverticulum in the ascending colon.
Diverticular haemorrhage, colon, Fig.1 (a)
Diverticular haemorrhage, colon, Fig.1 (b)