Neonatal portal vein thrombosis (PVT) is an uncommon but clinically important vascular complication, often associated with umbilical venous catheter (UVC) use. The optimal management strategy, including the role of anticoagulation, remains uncertain. This retrospective case series included 13 neonates with PVT diagnosed in a level III NICU between January 2021 and December 2024. Clinical and imaging data were compared between infants with spontaneous thrombus resolution and those with persistent thrombosis. The median gestational age was 30.1 weeks, and the median birth weight was 875 g. All infants had UVC placement; every thrombus involved the left portal vein with intrahepatic extension, and all extended into the IVC. Two neonates (15.4%) received anticoagulation; the remainder were managed conservatively. Spontaneous resolution occurred in 6 of 13 cases (46.2%). Earlier diagnosis and higher birth weight were more frequent in the resolution group, although not statistically significant. No thrombus-related acute complications occurred during a median follow-up of 6 months. In this case series, nearly half of neonates with non-occlusive PVT showed spontaneous resolution without anticoagulation. These findings suggest that conservative management can be considered in clinically stable infants, but the short follow-up precludes firm conclusions regarding long-term safety. Ongoing surveillance is essential to detect late complications such as portal hypertension or portosystemic shunting.