Edema after femoropopliteal bypass surgery: lymphatic and venous theories of causation.

Edema of a lower extremity after femoropopliteal bypass surgery is a common problem. To study the causes of this phenomenon we evaluated 72 patients before and after surgery with noninvasive venous testing and venography. We also obtained postoperative lymphangiograms of a sample of 16 patients, eight with and eight without postoperative edema. Patients were sequentially assigned to one of four treatment groups: group A, a lymphatic-preserving inguinal dissection with conventional popliteal dissection; group B, a lymphatic-preserving popliteal dissection with conventional inguinal dissection; group C, lymphatic-preserving inguinal and popliteal dissections; group D, conventional inguinal and popliteal dissections. Twenty-nine (40%) of the 72 patients had postoperative edema. A similar proportion of patients with edema had deep venous thrombosis as patients without edema (3/29 [10%] vs 3/43 [7%], respectively). Patients in group D showed the highest incidence of edema, 17/20 or 85%, a rate significantly higher than the rates in the other three groups (p less than 0.001). Results of lymphangiograms were normal in six of the eight patients without edema (the other two had slight disruption), whereas they showed severe lymphatic disruption in all eight patients with edema. No association was found between edema and type of graft used or severity of preoperative symptoms. This study indicates that deep venous thrombosis is not an important cause of edema that occurs after bypass surgery and that intraoperative lymphatic disruption probably causes most cases of this complication.