Congenital portosystemic shunt (CPSS) is a rare vascular anomaly in which portal vein blood flows into the systemic circulation without passing through the liver. They occur in approximately 1 in 30,000-50,000 live births. We present an 11-year-old patient with an extrahepatic CPSS managed with long-term follow-up. The initial clinical presentation showed no significant abnormalities. Subsequent assessments revealed slightly elevated ammonia (NH) and total bile acids (TBAs). Two times angiography at the ages of 2 and 11 years confirmed a shunt between the portal vein and left renal vein, with a gradual shift in blood flow dominance from the celiac artery-splenic vein system to the superior mesenteric artery-superior mesenteric vein system as the patient aged. Due to the risk of complications, transcatheter shunt embolization was performed, utilizing 12 coils to achieve complete shunt embolization. Post-embolization, NH3, and TBA levels normalized, and the patient remained asymptomatic. This case highlights the importance of timing in CPSS intervention, particularly with shifting hemodynamics and underscores the need for further studies on optimal intervention timing in pediatric CPSS.
