Wow, that portal vein is small: preventing portal vein thrombosis in liver transplantation for small children.

Portal vein thrombosis after pediatric liver transplantation is a common and devastating complication. Occurring in up to 8% of pediatric liver transplant recipients who are less than 15 kg, it frequently leads to graft loss and the need for emergent retransplantation. Children with biliary atresia are at particularly high risk and often develop an atretic portal vein; this makes the portal vein anastomosis particularly difficult. Adding further complexity is the frequent use of left lateral segment allografts, which frequently introduce portal vein size mismatching and orientation issues. Several options exist for managing the technical challenges related to portal vein anastomoses. Although the traditional approach has been end-to-end portal vein anastomoses, size differences often make this approach impossible. When this is the case, a proximal mesenteric vein anastomosis, branch vein patch, or donor venoplasty may be necessary to complete the anastomosis. When angulation issues result in low portal flow after transplantation, augmentation can be achieved through the ligation of the left renal vein or other mesocentral venous collaterals. Portocaval and porto-arterial anastomoses have also been proposed to increase flow. Although these approaches may effectively lower the risk of portal vein thrombosis after liver transplantation, they are less than optimal solutions for pediatric recipients with diminutive portal veins or preoperative portal vein thrombosis. A potential answer to this issue may be the use of a renoportal anastomosis. This approach has been described in adult liver transplantation with promising results. In pediatric patients, we believe that this technique provides a unique solution to issues relating to flow, size, and orientation mismatch. In general, there are no specific criteria for using a renoportal anastomosis; however, we find that size mismatch and portal flow issues are the most frequent indications. If the recipient portal vein measures 2 to 3 mm in size or is less than half the diameter of the donor portal vein, we often consider this technique. Additionally, if the portal vein flow is inadequate despite clamping of the left renal vein, we will also consider this approach.