Background and purpose: Congenital portosystemic shunts (CPSS) are associated with multisystem complications, with the most common being liver tumors. The purpose of this study is to investigate the incidence of complications of CPSS, and to determine the natural history of liver tumors and their relationship with shunt closure.

Methods: Single-center retrospective cohort study of patients with CPSS referred from 1990 to 2020. Data on demographics, laboratory, radiological and histological investigations, clinical evolution, and surgery were reviewed. Mann-Whitney for continuous data and Fisher's exact test for categorical data were used. A p value of 0.05 was considered significant.

Results: 54 patients were investigated for CPSS with a median age of 1.1 years (IQR 0.2-11.8 years) at presentation-7 intrahepatic shunts resolved spontaneously and were excluded. Type 1 (without intrahepatic portal flow) had a higher rate of all hepatic tumors than Type 2 (partial intrahepatic portal flow) [18/22(82%) vs. 9/25(36%); p = 0.003); and malignant tumors (6/22(27%) vs 1/25(4%); (p = 0.04). Following shunt closure, 4/11(36%) of patients experienced partial and 3/11(27%) complete tumor regression. Pulmonary hypertension and hepatopulmonary syndrome affected 4(9%), and 3(6%) patients, respectively. Pulmonary complications affected 1 patient with Type 1 and 6 with Type 2 shunts (p = 0.1). Neurocognitive anomalies were identified in 16/47(34%) patients, 8/22(35%) with Type 1 shunts and 8/25(32%) with Type 2 shunts (p = 0.76). 9/47 (19%) required special needs schooling.

Conclusions: Severity of portal venous deprivation (Type 1 CPSS) increases the risk of hepatic tumors and surgical closure is associated with a reduction in size or complete resolution of benign tumors.