IS Case 61: Bleeding Diverticulosis
Imaging Sciences URMC 2008
Publication Date: 2009-05-19
A 76-year-old male presented to the emergency department with frank bright red blood per rectum. Emergent angiography revealed bleeding from a branch of the right middle colic artery of the superior mesenteric artery at the right hepatic flexure (Figs. 1-3). After super-selection of the bleeding branch, coil embolization was performed (Figs. 4-5). Gastrointestinal (GI) bleeding resolved and patient was discharged 4 days later. Three hours after discharge patient returned with second GI bleed, at which time nuclear medicine tagged red-blood-cell scan revealed bleeding at the hepatic flexure (Fig. 6). Angiography showed new hemorrhage in a branch of the middle colic artery of the superior mesenteric artery, near the site of previous hemorrhage. A larger branch of the middle colic artery was then coil embolization. This procedure was technically successful. However, the patient went on to develop peritonitis and elevated white-blood-cell count. Surgical exploration revealed diverticulosis (Fig. 7) and ischemic colitis.
See figure legends.
Acute lower gastrointestinal (GI) hemorrhage accounts for approximately 20% of all cases of GI hemorrhage. The annual incidence is about 20-30 cases per 100,000 population in westernized countries . Mortality rates are reportedly 10-20% and are dependent on age (>60 years), multiorgan system disease, transfusion requirements in excess of 5 units, need for operation, and recent stress (e.g., surgery, trauma, sepsis) . Lower intestinal hemorrhage is one fifth as common as upper gastrointestinal hemorrhage . Localization of hemorrhage relative to the Treitz ligamentum directs the initial evaluation and resuscitation. The passage of maroon stools or bright red blood from the rectum is usually indicative of lower intestinal bleeding.
In 1996, Vernava and colleagues studied the common causes of lower GI bleeding in adults by serving 4410 patients . They found that 60% of patients had diverticular disease (large or small bowel), 13% had IBD, 11% had benign anorectal diseases (hemorrhoids, anal fissure, fistulo-in-ano), 9% had a neoplasia (small or large intestine, rectum or anus), 4% had colagulopathy and 3% had an arteriovenous malformation. Smaller studies have shown variation in these numbers, but diverticulosis is usually the most common cause.
Although some what debated in the literature, evaluation of lower intestinal bleeding commonly begins with a Tc99m-labeled red blood cell scan. Radionuclide scintigraphy is advocated for two primary purposes: as a guide for surgical resection and as a screening test prior to angiography. Among the advantages of radionuclide scanning are its sensitivity for bleeding as low as 0.05 to 0.1 ml/min  and its noninvasive nature. In addition, no bowel preparation is required, venous and arterial bleeding can both be detected, and repeat scans can be easily performed in the event of recurrent bleeding.
Selective mesenteric angiography may permit the identification of vascular abnormalities, the precise bleeding point, and using superselective embolization of the mesenteric vessels, treat massive lower GI bleeding. Angiography is less sensitive than radionuclide scanning with the ability to detect bleeding of more than 0.5 ml/min . Autologous clot, Gelfoam, polyvinyl alcohol, microcoils, ethanolamine, and oxidized cellulose can be used as embolic agents. Embolization involves superselective catheterization of the bleeding vessel to minimize necrosis, the most feared complication of ischemic colitis. Ischemic necrosis and failed embolization is typically treated with bowel resection.
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