[Gastrointestinal haemorrhage due to aorto-intestinal fistula. 3 cases (author's transl)].

Three types of aorto-intestinal fistula may be associated with gastrointestinal bleeding: primary fistulae from an aneurysm, secondary fistulae related to an aorto-prosthetic anastomosis and paraprosthetic fistulae by intraduodenal protrusion of a graft. The prevalence of secondary and paraprosthetic fistulae increases with more widespread vascular surgery. Only if the diagnosis is always borne in mind in a patient with an aneurysm or an aortic prosthesis makes it possible to recognise an aorto-intestinal fistula in time. Upper GI series and endoscopy are more useful in reaching a diagnosis than arteriography but signs must be sought in the third and fourth parts of the duodenum. The lesion may even be missed on surgical exploration, being concealed before separation of the aorta and duodenum. Infection and the underlying general medical condition are factors in the gravity of the operative prognosis. One of our three patients treated surgically was saved by the insertion of an extra-anatomic bypass. The prognosis in paraprosthetic fistulae, the possible precursor stage of a secondary aorto-digestive fistula, is more favourable.