Methylene Blue injection via superior mesenteric artery microcatheter for focused enterectomy in the treatment of a bleeding small intestinal arteriovenous malformation

Abstract

IntroductionObscure gastrointestinal bleeding from the small intestine may present the Acute Care Surgeon with a formidable diagnostic and therapeutic challenge. Despite the current array of diagnostic studies, localization of the causative pathology may be elusive, especially when the bleeding is intermittent. When a small intestinal arteriovenous malformation is the responsible lesion, a technique combining super-selective angiography with intra-operative methylene blue injection and focused enterectomy has been described in a number of case series. The current case report utilizes this same approach with emphasis on computed tomography angiography representing a key first step in the diagnostic algorithm.Case reportIn this case report, we describe the diagnosis and treatment of obscure gastrointestinal bleeding emanating from an arteriovenous malformation in the small intestine of a 52 year old male. After an extensive work-up including upper and lower endoscopy, double balloon enteroscopy and capsule endoscopy, he was referred for computed tomography angiography. Though he was not actively bleeding, a jejunal arteriovenous malformation was localized on imaging. This prompted directed transfemoral angiography, placement of a super-selective microcatheter in the 4th jejunal arterial branch, intra-operative methylene blue injection and focused enterectomy with pathological confirmation. The patient was found to be free of gastrointestinal bleeding on 6 month follow-up.ConclusionsA step-wise, rational diagnostic approach should be utilized in the evaluation of obscure gastrointestinal bleeding. In the non-actively bleeding patient, computed tomography angiogram may facilitate the diagnosis of a small intestinal arteriovenous malformation. Methylene blue injection via a super-selective angiographic microcatheter may then allow for focused enterectomy.

ACG Clinical Guideline: Diagnosis and Management of Small Bowel Bleeding

“…Diagnostic yields were 100% for patients with ongoing overt bleeding, 70% in overt previous bleeding, and 50% in occult bleeding with an overall mortality rate of 2%. An interesting combined radiological and surgical option has been recently re-reported involving angiographic localization of small bowel vascular lesions ( 227 ). Th e angiographic catheter is left in place and the patient is transferred to the operating room.…”

Bleeding from Small Intestine: No Man's Land

“…Injection of methylene blue through supraselective catheter enables selective resection of small bowel that contains bleeding lesion, if embolization is unsuccessful or severe bleeding recurs. 35 Once VCE identifies a bleeding lesion, the patient undergoes either push enteroscopy, if it is proximal lesion, or deep entoeroscopy. Once endoscopic treatment is successful, the patient is monitored for signs of rebleeding.…”

Management of Multiple Arteriovenous Malformations of the Small Bowel

“…However, it is exceedingly challenging to identify the location of lesions and determine the optimal surgical margin, especially in cases where there are multiple AVMs in the small bowel. A technique combining selective angiography with intraoperative methylene blue injection to aid the localization of obscure sources of GI bleeding, including AVMs, has been described in a number of case reports [9–11]. Although no reports described complications of this methylene blue injection technique, doses of 500 mg or greater of methylene blue can cause nausea, abdominal and chest pain, altered mental status, and methemoglobinemia [10, 12].…”