Aorto-enteric fistula as clinical entity.

A 19 year experience (1958-1977) with aortoenteric fistulas is presented. An aorto-enteric fistula is a direct communication between the aortic lumen and the gastro-intestinal tract producing a gastro-intestinal bleeding. The commonest cause of a primary or spontaneous aorto-enteric fistula is aneurysm formation. If there has been an operation on the aorta then the aorto-enteric fistula is called secondary. No primary aorto-enteric fistulas were encountered but thirteen secondary aorto-enteric fistulas are reported on a total of 841 aorto-femoral by-pass operations reviewed. Six hundred and sixty-one of these had an acceptable follow-up: this gives a 2% incidence. Our survival rate is 40%. Four different possible mechanisms are proposed for the formation of the secondary aorto-enteric fistula: anastomotic aneurysm formation, fibrous reaction, intra- or postoperative contamination or a combination of these possibilities. Some etiological factors as type of anastomosis, suture material, prosthesis material, hypertension, end-arterectomy and preoperative aneurysmatic tendency are analysed. A study is made of the different available diagnostic tools and the different possible therapies are discussed.