Study of movement of umbilical venous catheters over time.

AIM: To quantify, in well-positioned umbilical venous catheters (UVC), the direction and magnitude of catheter tip migration.

METHODS: In this prospective, single-centre, observational, cohort study, infants with a UVC inserted that reached the target zone - inferior vena cava, from ductus venosus to cavoatrial junction (CAJ) - were included. Ultrasound was used to position the catheter tip as near to the CAJ as possible at insertion and to guide any subsequent withdrawals of the catheter. Radiographs and ultrasound were repeated the day following the insertion of the UVC and on any day following adjustment. A final scan was performed on the day of catheter removal. The anatomical position of the catheter and its distance from the CAJ was recorded with each scan.

RESULTS: The study ran from May 2015 to August 2016 in the neonatal unit at the Royal Brisbane and Women's Hospital. Thirty-eight patients were recruited, but 18 failed to negotiate the ductus venosus. For the remaining 20, the initial UVC position was within 3 mm of the CAJ on ultrasound. Subsequently, on day 2, 25% of catheters were well positioned, 65% were high and 10% were below the target zone. On the late scan prior to UVC removal, 90% of catheters had migrated from their position on the preceding scan: outward migration in 80% of cases ranging from 2 to 23 mm (median 8.5 mm). Only 35% of catheters remained well positioned.

CONCLUSION: The majority of UVCs migrate over time, usually inwards initially and then outwards to a low position.