UNLABELLED: Umbilical venous catheterization is a common procedure performed in intensive care units. Point-of-care ultrasonography enables efficient vascular access and reliable assessment of catheter tip position. This prospective study aimed to determine whether the angle formed between the terminal segment of the umbilical vein (UV) and the initial segment of the ductus venosus (DV) can predict successful umbilical venous catheter (UVC) placement in the inferior vena cava, and to evaluate the effectiveness of ultrasound-guided navigation. Between 2021 and 2023, 78 neonates in a single-center study underwent umbilical venous catheterization. Ultrasonography, performed by an experienced ultrasonographer, was used to assess UVC tip position, DV caliber, and the UV-DV angle. After identifying catheter tip malposition, infants were classified into two groups: low and correct catheter positions. Ultrasound-guided maneuvers were applied to achieve optimal tip placement. The umbilical vein-ductus venosus (UV-DV) angle differed significantly between low and correctly positioned UVCs, median 136.9° (IQR 128.8-151.5°) vs. 157.4° (IQR 151.4-164.6°), p < 0.001. In multivariable analysis, both the UV-DV angle (p = 0.0032) and ductus venosus caliber (p = 0.0047) were independent predictors of correct catheter positioning. The catheter was correctly positioned on the first attempt in 73% of cases, increasing to 85% after adjustment maneuvers. CONCLUSION: These findings highlight the usefulness of ultrasound navigation for effective UVC placement and the UV-DV angle appears to be a promising ultrasound marker for predicting optimal catheter positioning. The study was approved by the Bioethics Committee of the Medical University of Warsaw No. KB/110/2020 and retrospectively registered at ClinicalTrials.gov (NCT07434102) on 25.02.2026. WHAT IS KNOWN: • Umbilical venous catheterization is associated with complications related to incorrect catheter positioning. • Thoracoabdominal radiography has traditionally been used to assess UVC tip position; however, point-of-care ultrasound provides the most accurate evaluation. WHAT IS NEW: • The umbililcal vein-ductus venosus angle may serve as a novel ultrasound marker of difficult UVC advancement and may support bedside procedural planning. • Point-of-care ultrasound emerged as an essential tool for guiding maneuvers to achieve correct catheter positioning.