Anastomotic femoral pseudoaneurysm: an investigation of occult infection as an etiologic factor.

Occult infection was investigated as an etiologic factor in the formation of femoral anastomotic pseudoaneurysms associated with prosthetic vascular grafts. Forty-five femoral pseudoaneurysms with no clinical evidence of infection 10 to 173 months after prosthetic graft placement were consecutively studied. The explanted Dacron or explanted polytetrafluoroethylene graft material was cultured in trypticase soy broth and ultrasonically oscillated to remove adherent bacteria. All patients were treated by excision of the pseudoaneurysm and surrounding perigraft capsule and in situ replacement with an interposition prosthetic graft. Thirty-two bacterial isolates were recovered from 27 (60%) of the specimens, with coagulase negative staphylococci (Staphylococcus epidermidis S. warneri, S. hominis, S. capitis) accounting for 24 of the recovered species. No infection of the replacement graft developed in any patient and no recurrent pseudoaneurysms were observed. Bacterial colonization may occur at implantation or during subsequent procedures when the prosthetic graft is exposed. This chronic infection can be diagnosed by means of sensitive culture techniques that dislodge adherent bacteria from the graft surface. On grounds of the observations reported in this study, there appears to be suggestive evidence that an occult infectious process may be one of the factors that play a role in the development of some femoral anastomotic pseudoaneurysms.