Changes in venous hemodynamics after renal transplantation.

To explain an occasionally observed transient swelling of the ipsilateral leg in renal transplant recipients in the absence of deep vein thrombosis, we took serial measurements of venous outflow resistance and duplex examinations of both legs. Fourteen recipients of a living related donor kidney graft were submitted to strain gauge plethysmography and duplex examination before transplantation and 1 and 6 weeks thereafter. Venous outflow resistance and venous flow were measured and the veins were assessed for thrombosis. Strain gauge plethysmography showed a significant increase in venous outflow resistance in the leg on the side of the renal transplant 1 week after transplantation [0.28 +/- 0.13 vs 0.40 +/- 0.15 mmHg.s (ml/100 ml)-1; P < 0.05]. Six weeks later, the venous outflow resistance had returned to preoperative values [0.30 +/- 0.11 mmHg.s (ml/100 ml)-1; P = NS]. On the contralateral side, no significant differences were found. Duplex examinations showed no signs of thrombosis. Venous flow measurements in the common femoral vein showed no significant differences. We conclude that the additional blood supply to the iliac veins results in an increase in venous outflow resistance in the ipsilateral leg, which can explain the observed swelling of this leg and may have implications for the preferred method of diagnosis of venous thrombosis after renal transplantation.