Experience with duplex sonographic evaluation of meso-rex bypass in extrahepatic portal vein obstruction

Meso-Rex bypass is a surgical procedure for managing extrahepatic portal vein obstruction in children. Although duplex sonography has been used for assessing the patency of the bypass graft and the changes in the intrahepatic portal venous system after the surgery, there was little sonographic description of functioning and dysfunctioning bypass grafts found in the literature. In this case series, we retrospectively evaluated duplex sonography of functioning and dysfunctioning bypass grafts in 5 pediatric patients who received meso-Rex bypass grafts. Sonography was performed preoperatively and postoperatively within 48 hours, 1 to 2 weeks later, and at follow-up 1 month and up to 3 years later. Changes in the direction and velocity of the flow in the intrahepatic portal veins and bypass grafts and diameters of the grafts and the left portal veins were analyzed. Preoperative sonography revealed varied extension of extrahepatic portal vein occlusion with cavernous transformation and diminished intrahepatic portal venous flow, whereas postoperative studies showed a rapid increase of the intrahepatic portal flow via the meso-Rex bypass graft in all cases. A patent graft with reversed flow in the left portal vein was a predominant feature of a functioning graft. In contrast, absent flow in the graft with diminished flow or an altered flow direction in the left portal vein indicated graft failure. It is believed that duplex sonography provides a valuable tool for monitoring the hemodynamic changes in the portal venous system and detecting graft malfunction.