Objective:To evaluate the safety and efficacy of using small and ultra-small sized grafts for in situ auxiliary liver transplantation in the treatment of portal hypertension.Methods:A prospective single-arm cohort study was conducted. Patients who underwent liver transplantation at Beijing Friendship Hospital from December 2014 to July 2025 were included. Intraoperative portal vein pressure was routinely monitored, with the target regulation for portal vein blood flow set at<15 mmHg (1 mmHg=0.133 kPa) and follow-up continued until September 2025. The primary endpoints were the patient's status and graft survival. The secondary endpoints were small-for-size syndrome and perioperative complications. The small-for-size syndrome was graded according to the 2023 International Liver Transplantation Society consensus statement.Results:A total of 33 cases were enrolled. Among them, 22 had ultra-small size grafts, 11 had small-size grafts, 28 had living donor grafts, and five had split grafts. The graft-to-recipient weight ratio in living donor liver transplantation was 0.31%～0.79%, while in split liver transplantation it was 0.45%～1.02%. Intraoperative portal vein pressure of ≥15 mmHg was observed in 11 cases, who underwent portal vein blood flow adjustment via splenic artery ligation (2 cases), partial splenectomy (8 cases), and/or restrictive portocaval shunting (1 case), after which all patients achieved the target portal vein pressure. All cases completed at least one month of follow-up, with 28 cases following for more than one year, and the median follow-up period was 36.5 months. Early-stage postoperative small-for-size syndrome occurred in eight cases (24.2%, 8/33), all classified as grade A, with improvements following supportive treatment. Severe complications (Clavien-Dindo≥Ⅲ) occurred in three cases (9.1%, 3/33). The one-year survival rate was 92.9% (26/28). The overall survival rate at the end of follow-up was 90.9% (30/33). No patients experienced graft loss or death due to small-for-size syndrome. Graft tissue tested negative for hepatitis B core antibody and covalently closed circular DNA, and hepatitis B surface antigen seroconversion was achieved following second-stage residual liver resection and under a combined strategy of potent nucleos(t)ide analogs and hepatitis B immunoglobulin in ten cases of hepatitis B-related disease.Conclusions:With standardized portal vein blood flow monitoring and individualized portal vein blood flow adjustment, in situ auxiliary liver transplantation can safely and effectively use small and even ultra-small sized grafts, thereby significantly expanding graft sources and ensuring donor and recipient safety. These findings warrant further validation and promotion in multicenter controlled studies.

Objective:To evaluate the safety and efficacy of using small and ultra-small sized grafts for in situ auxiliary liver transplantation in the treatment of portal hypertension.Methods:A prospective single-arm cohort study was conducted. Patients who underwent liver transplantation at Beijing Friendship Hospital from December 2014 to July 2025 were included. Intraoperative portal vein pressure was routinely monitored, with the target regulation for portal vein blood flow set at<15 mmHg (1 mmHg=0.133 kPa) and follow-up continued until September 2025. The primary endpoints were the patient's status and graft survival. The secondary endpoints were small-for-size syndrome and perioperative complications. The small-for-size syndrome was graded according to the 2023 International Liver Transplantation Society consensus statement.Results:A total of 33 cases were enrolled. Among them, 22 had ultra-small size grafts, 11 had small-size grafts, 28 had living donor grafts, and five had split grafts. The graft-to-recipient weight ratio in living donor liver transplantation was 0.31%～0.79%, while in split liver transplantation it was 0.45%～1.02%. Intraoperative portal vein pressure of ≥15 mmHg was observed in 11 cases, who underwent portal vein blood flow adjustment via splenic artery ligation (2 cases), partial splenectomy (8 cases), and/or restrictive portocaval shunting (1 case), after which all patients achieved the target portal vein pressure. All cases completed at least one month of follow-up, with 28 cases following for more than one year, and the median follow-up period was 36.5 months. Early-stage postoperative small-for-size syndrome occurred in eight cases (24.2%, 8/33), all classified as grade A, with improvements following supportive treatment. Severe complications (Clavien-Dindo≥Ⅲ) occurred in three cases (9.1%, 3/33). The one-year survival rate was 92.9% (26/28). The overall survival rate at the end of follow-up was 90.9% (30/33). No patients experienced graft loss or death due to small-for-size syndrome. Graft tissue tested negative for hepatitis B core antibody and covalently closed circular DNA, and hepatitis B surface antigen seroconversion was achieved following second-stage residual liver resection and under a combined strategy of potent nucleos(t)ide analogs and hepatitis B immunoglobulin in ten cases of hepatitis B-related disease.Conclusions:With standardized portal vein blood flow monitoring and individualized portal vein blood flow adjustment, in situ auxiliary liver transplantation can safely and effectively use small and even ultra-small sized grafts, thereby significantly expanding graft sources and ensuring donor and recipient safety. These findings warrant further validation and promotion in multicenter controlled studies.

Small-for-size syndrome is one of the most common and dangerous complications of partial liver transplantation. With the accumulation of clinical experiences and basic researches developed in recent years, new knowledge about the pathogenesis, pathophysiological process, prevention and treatment of small-for-size syndrome has been established. This article summarizes the progress of research on the small-for-size syndrome in recent years to help better diagnosis, prevention and treatment, thus improving the prognosis and long-term survival of patients.