Objectives To evaluate the umbilical venous catheter (UVC) tip position by ultrasound and compare it with standard radiograph findings and to examine the catheter tip migration rates during the first week of life.

Design Prospective observational study of inborn preterm infants who had an UVC placed and its position radiographically confirmed. The first ultrasound was done on UVC placement at median (IQR) age of 2 hours (1–4) and follow-up scans at a median (IQR) age of 34 hours (27–44 hours), 77 hours (70–94 hours) and 6 days (5–7 days) after insertion. Catheter tip was considered in optimum position if tip was lying in the inferior vena cava up to the right atrium opening.

Results We studied 65 infants at a mean (±SD) gestational age and birth weight of 26.4 (±2.1) weeks and 808 (±289) g, respectively. Ultrasound confirmed optimum position of UVC tip in 25/65 (38.5%) infants. Majority (38/40) of the malpositioned catheters were located inside the heart with 15 reaching the left atrium. Catheter tip migration occurred in 29 of 58 infants (50%) at any time during the first week. The proportions of UVC migration were found to be 17%, 31% and 29% on subsequent ultrasound with a trend to outward movement over time.

Conclusion UVC tip localisation by standard radiography is very imprecise, and catheter tip migration occurs in a significant proportion of infants during first weeks of age. We suggest ultrasound as the best modality to assist localisation and follow-up of UVC tip in preterm infants.