Saturday, November 17, 2018

True or False #8 Lower GI Bleed

1. Angiodysplasia is a high volume arterial bleed. T or F

2. Diverticulosis is a low volume arterial bleed. T or F



Angiodysplasia  more often than not involves low volume venous bleeding.

Angiodysplasias are composed of ectatic, dilated, thin-walled vessels that are lined by endothelium alone or endothelium along with small amounts of smooth muscle. Studies in which casts of angiodysplasias were made by injecting a silicone material demonstrated that the most prominent feature in angiodysplasias is the presence of dilated, tortuous submucosal veins.
Small arteriovenous communications are also present and are due to incompetence of the precapillary sphincter. Enlarged arteries may be seen in larger angiodysplasias and may be associated with arteriovenous fistulas, which explains why bleeding can be brisk in some patients.
Histologic confirmation is often difficult. When obtained, it shows dilated vessels in the mucosa and submucosa, sometimes covered by only a single layer of surface epithelium.


Diverticular bleeding involves high volume arterial bleed

Diverticular bleeding — As a diverticulum herniates, the penetrating vessel responsible for the wall weakness at that point becomes draped over the dome of the diverticulum, separated from the bowel lumen only by mucosa. Over time, the vasa recta is exposed to injury along its luminal aspect, leading to eccentric intimal thickening and thinning of the media. These changes may result in segmental weakness of the artery, predisposing to rupture into the lumen. Diverticular bleeding typically occurs in the absence of diverticulitis

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