Diagnostic value of ultrasonography for post-liver transplant hepatic vein complications

Liver transplantation (LT) is the most effective treatment for patients with end-stage liver disease, and maintaining vascular patency of the transplanted liver is one of the crucial prerequisites for surgical success. Despite hepatic vein complications following LT occurring at a relatively low frequency, ranging between 2% to 11%, delayed diagnosis and treatment may lead to graft dysfunction and even patient mortality. Clinical manifestations of hepatic vein complications are often subtle and nonspecific, posing challenges for early diagnosis. Signs may initially present as mild abnormalities in liver function, delayed recovery of liver function, unexplained ascites, lower limb edema, and perineal edema. Prolonged duration of these complications can lead to hepatic sinusoidal dilatation and eventual liver failure due to prolonged hepatic congestion. Ultrasonography has become the preferred imaging modality for post-liver transplant evaluation due to its convenience and non-invasiveness. Although hepatic vein complications may manifest as disappearance or flattening of the hepatic vein spectrum on routine ultrasound imaging, these findings lack specificity. Contrast-enhanced ultrasound that visualizes the filling of contrast agent in the hepatic veins and dynamically displays blood flow perfusion information in the drainage area can, however, significantly improve diagnostic confidence and provide additional information beyond routine ultrasound examination.