Duplex Sonography after Living Donor Kidney Transplantation: New Insights in the Early Postoperative Phase

Abstract

Vascular complications of kidney transplantation, including transplant vein thrombosis, are relevant causes for graft loss in the early postoperative phase. However, duplex flow characteristics after living renal transplantation are widely unknown. Aim of the study was to assess renal perfusion in the postoperative period with special emphasis on the renal vein. 22 consecutive kidney graft recipients and their donors were included and prospectively followed up for three months. The following Doppler parameters were collected: in the donor before operation: the intrarenal resistive index (RI), in the recipient after transplantation and at one and three months: the intrarenal RI, peak flow velocities and area under the curve in the renal vein, as well as peak systolic velocities of the iliac and renal artery. None of the 22 transplants failed due to vascular complications. Highest median venous (92 cm/s [range 22-211]) and arterial peak velocities (271.5 cm/s [141.5-458]) were observed close to the anastomosis immediately after transplantation. During follow-up, flow parameters significantly decreased at three months (44.3 cm/s [13.3-156.9] and 186.8 cm/s [105.5-267.5]). The RI decreased from donor to recipient at the day of operation due to tachycardia (0.65 to 0.60; P = 0.06). After correction for heart rate, the RI was stable during follow-up. Initial high peak velocities in conjunction with stable resistive indices in a cohort, free of vascular graft complications, suggest a postoperative physiologic adaptation process rather than a relevant stenosis requiring medical intervention.