Angiography
Discuss the braod indications for angiography?
Angiography is used for accurate localization as well as treatment of both upper and lower GI bleeding. Angiography is typically done in the setting of an acutely unstable patient, after a negative or failed endoscopic evaluation, or as a first-line examination for lower GI bleed.
Discuss the accuracy of angiography?
Bleeding rates as low as 0.5 mL/min can be detected with selective catheter angiography. Angiography has a sensitivity of 63%–90% and 40%–86% for upper and lower gastrointestinal bleeding, respectively, and a specificity of up to 100% for both.
How is GI bleed diagnosed at angiography?
Extravasation of contrast material into the bowel lumen is pathognomonic for active GI bleed. Indirect signs include detection of pseudoaneurysm, arteriovenous fistula, hyperaemia, neovascularity, and extravasation of contrast material into a confined space. Although the cause of a bleeding lesion can occasionally be determined, the angiographic appearance of gastrointestinal bleeding is often non-specific, and further diagnostic testing may be required following transcatheter localization and treatment.
What techniques are used to control bleeding at angiography?
Embolization of the bleeding vessel is the mainstay of transcatheter treatment for nonvariceal gastrointestinal bleeding, and high technical success rates (angiographic cessation of bleeding) of 91%–100% have been reported. Clinical success rates (cessation of bleeding for 30 days) of 68%–82.5% for upper gastrointestinal bleeding and 81%–91% for lower gastrointestinal bleeding have been reported.
Microcoil embolization is typically preferred within the lower gastrointestinal tract, whereas controversy exists regarding the optimal agent within the upper gastrointestinal tract. In fact, combinations of different embolic agents may be more effective than embolization with a single agent in the upper gastrointestinal tract. Common embolic agents include microcoils, polyvinyl alcohol particles, gelfoam, n-butyl cyanoacrylate glue, and enbucrylate tissue adhesive.
Ref: Laing CJ et al. RadioGraphics 2007
What are the specific indications of angiography?
- Upper GI bleed- rebleeding following endoscopic therapy. Optimum management is based upon clinical judgement, local expertise and is best undertaken following discussion between surgeons and physicians. Options include:
- Repeat endoscopic treatment- one trial randomised 100 patients who re bled following endoscopic therapy for ulcer bleed to operative surgery or repeat endoscopic treatment. 30 day mortality and transfusion requirements were low and similar in both groups
- Selective arterial embolization- a single retrospective comparison between surgery and embolization showed no difference in mortality or rebleeding. Embolisation in small cohort studies shows high rates (98%) of technical success and low (4-5%) complication rates (hepatic/splenic infarction, duodenal ischaemia)
- Surgery
- Lower GI bleed: A large majority (80-85%) of lower GI bleed will stop bleeding spontaneously without any specific treatment. In patients with massive lower GI haemorrhage, colonoscopic haemostasis is an effective means of controlling haemorrhage from active diverticular bleeding or post polypectomy bleeding.
- If colonoscopy fails to define site of bleeding and control haemorrhage, angiographic transarterial embolisation is recommended as an effective means of controlling haemorrhage.
- Localised segmental resection or subtotal colectomy is recommended for the management of colonic haemorrhage uncontrolled by other techniques.
