Editor—We describe the use of the double catheter technique for umbilical venous catheterisation. Such a technique has been described before for the cannulation of the umbilical arteries,1 but to our knowledge has not been described for umbilical venous catheter (UVC) insertion.

One of the major problems with insertion of UVCs is failure of the catheter to negotiate the ductus venosus, thereby preventing it traversing the inferior vena cava (IVC).2 3 If this occurs the double catheter technique can be used as follows. After the UVC is inserted in the standard way and an x-ray picture shows the catheter tip has lodged either in the portal vein (or tributaries) or the left or right hepatic portal veins (or branches), then a second catheter is inserted in the UV whilst the first remains in situ. The first catheter is then withdrawn and the second fixed in place. An x-ray picture is then repeated.

We used the double catheter technique on two occasions in 1996: in a 4350 g term baby with group B streptococcus sepsis. The first UVC lodged in the liver. A second catheter placed down the side of the first resulted in successful negotiation of the ductus venosus and right atrium. The second occasion was in a shocked 31 week gestational age infant. The first UVC was seen lodged in the portal vein, and the second UVC passed through the ductus venosus and IVC to end up in the right atrium. There were no known complications of the procedure in either case.

Our explanation for the success of this technique is as follows. The UV ends in the left hepatic portal vein opposite the entrance to the ductus venosus.2 4 Failure of the catheter to enter the ductus venosus occurs because, firstly it is narrowest at its origin, and functional closure occurs here soon after birth, and secondly the ductus venosus inlet may not be aligned on the opposite side of the left hepatic portal vein.2 If the catheter fails to enter the ductus venosus it will then enter the left hepatic portal vein and either become lodged in the liver or in the portal vein (or its tributaries). The first catheter takes the course of least resistance and blocks this undesirable route. The second catheter inserted down the side of the first then has a far greater chance of entering the ductus venosus to continue on to its more desirable location.

We believe this technique is useful for those of us who provide neonatal intensive care. While the adverse effects of this technique remain largely unstudied, it would be prudent to use it only in those infants in whom an umbilical venous catheter is absolutely necessary.