Click on Images for Enlarged View

Findings: The first two images are selective inferior mesenteric artery catheterization and injection which show pooling of contrast from sigmoid branches in the center of the image. Images 3 and 4 show selective IMA catheterization and injection after embolization was performed with metallic coils. These images show that the puddling of contrast no longer occurs.

Diagnosis: Lower GI bleeding represented by the puddling of contrast, which was treated successfully with coil embolization.

Discussion: Common causes of lower GI bleeding include diverticulosis, angiodysplasia, colonic polyps, or colonic cancers. Hemorrhoids are also common causes of lower GI bleeding. In this patient with a known history of sigmoid diverticulae, diverticulosis is the likely cause of this patient's bleeding. Lower GI bleeding can be localized using angiographic methods or nuclear scintigraphy. Nuclear scintigraphy is performed with Technetium 99m sulfur colloid or labeled red blood cells. A bleeding rate of .1 ml per minute is required to visualize GI bleeding. Nuclear scintigraphy also has the added benefit of serial imaging if the patient is not actively bleeding during the initial time the scans were obtained. Angiography requires a bleeding rate of approximately 1 ml per minute to visualize GI bleeding. GI bleeding can often be managed with conservative medical therapy. If this is not successful, percutaneous interventions can be performed. Selective vasopressin injection can be performed which causes vasoconstriction. However, subselective infusion should be avoided to minimize intestinal infarction. Complications of this therapy would include myocardial ischemia and cardiac arrhythmias. Embolization can be used with temporary materials such as gelfoam which only temporizes the patient through acute hemorrhage, and allow vessel recanalization to minimize tissue loss or ischemia. Permanent embolic materials such as polyvinyl alcohol and metallic coils are indicated if bleeding is the result of tumors, AV malformations, or large areas of hemorrhage. Complications would include embolization of nontarget vessels leading to ischemia and infarction. Infarction of the embolized tissue, in this case the sigmoid colon, is also a know complication. However, collateral vascular supply from the SMA or from rectal arteries occur to minimize this complication. If bowel ischemia or infarction does occur, surgery would be necessary to resect the infarcted section of colon.

References:
Gore L. Textbook of Gastrointestinal Radiology, 1994.

Baum, Pentecost. Abrams' Angiography, 1997.

Return to Interventional Imaging Page