Nomogram for Predicting Postoperative Early Biliary Complication in Adult Patients Following Liver Transplantation: a Retrospective Study

Background： Liver transplantation (LT) is a critical therapeutic intervention for patients with end-stage liver disease or acute liver failure, offering favorable outcomes with survival rates of 76-90% at 1 year and approximately 70% at 5 years . Despite significant advancements in surgical techniques, immunosuppressive protocols, and organ preservation, biliary complications (BCs) remain a substantial cause of morbidity and mortality, frequently necessitating long-term interventions such as endoscopic, percutaneous, or surgical procedures. The incidence of BCs post-LT is estimated to range from 5% to 20%, with most occurring within the first three months postoperatively, although some may present years after LT . Among BCs, the most common are anastomotic strictures (AS), non-anastomotic strictures (NAS), and bile leaks. Treatment approaches include endoscopic techniques, percutaneous transhepatic biliary drainage, and surgical interventions. NAS and bile leaks typically manifest within the first year post-transplant but may arise later, with bile leaks occurring immediately or within weeks following surgery . Early postoperative monitoring and timely management are essential to preventing and addressing these complications.

In adult liver transplantation, several factors contribute to bile duct complications, including biliary ischemia, surgical techniques, infections, and donor characteristics . Among these, insufficient arterial blood supply to the bile ducts is recognized as a key factor likely contributing to the development of biliary complications. Unlike the liver parenchyma, which receives blood from both the portal vein and hepatic artery, the bile ducts depend solely on arterial blood flow. About 60% of the common bile duct's blood comes from the gastroduodenal artery, with the remaining 30-40% from hepatic artery branches. After liver transplantation, blood flow from the gastroduodenal artery is often disrupted, making the hepatic artery's role in supplying the distal bile duct even more critical. This reduced arterial support highlights the significance of maintaining adequate hepatic artery perfusion to prevent bile duct complications.

Ultrasound is essential for monitoring post-liver transplantation biliary complications, providing detailed imaging for early detection of issues like strictures and leaks. Parameters such as arterial resistive index (ARI) and flow velocity are critical for assessing hepatic artery condition and blood supply post-transplantation, offering insights into graft perfusion and viability. These non-invasive metrics are crucial for evaluating hepatic arterial circulation, may provide effective postoperative care and improving patient outcomes.

After liver transplantation, biliary complications most commonly occur during the early postoperative period, particularly within the first three months. More than half of all biliary complications are early complications occurring at the anastomotic site. Hence, early monitoring and intervention are crucial to promptly detect and manage these potential complications, thereby improving patient prognosis and survival rates in clinical settings. However, there is limited research on the risk factors and predict model for 90 days biliary complications after adult liver transplantation. Nomogram is a simple visual graph of statistical prediction model with an easy-to-use graphical interface. Importantly, it could generate personalized predictions, thereby, widely used in risk stratification and personally providing approach to disease management. This study aimed to establish a nomogram model to evaluate patients who underwent LT to help clinicians predict the risk of 90 days biliary complications and provide a more personalized treatment strategy.

Method Patients Data from patients who underwent OLT between 1 January 2016 to 31 December 2021 at the First Affiliated Hospital of Sun Yat-sen University were retrospectively extracted from the electronic medical record system. Exclusion criteria included age <18 years old, multiple organ transplantation, retransplantation, died intraoperatively or within 3 months after LT, and cases with missing important data or over 20% of data missing. Finally, a total of 757 patients were enrolled. This research study was reviewed and approved by the Ethics Committee at Hospital, waiving the requirement for informed consent in alignment with the Declaration of Helsinki. All operations were performed in accordance with the standard procedures by experienced surgical groups in our department.