For radiograph and ultrasound scans performed within an hour of each other, the cardiac silhouette method more accurately predicts umbilical venous catheter tip than vertebral body level and methods described in previous studies. Catheters are frequently malpositioned. The length of the target zone for optimal umbilical venous catheter tip position is short. Ultrasound assessment of umbilical venous catheter tip position is quick.

Both OS and CS produced transient variable reductions in heart rate and Spo(2). During SIMV there was no difference between OS and CS in DeltaV(L) or t(rec). During HFOV there was no difference in DeltaV(L) but a slightly longer t(rec) after OS.

Differences of opinion in the literature are reflected by the heterogeneity in clinical practice across regions and within units. Crucial questions undergoing evaluation are whether data extrapolated from a previous area are relevant to PDA in modern neonatology and whether targeting treatment early can translate to improved clinical outcome.

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