Neonatal Vascular Access

Point of care ultrasound (POCUS) for central venous lines, umbilical venous lines/catheters (UVC) and umbilical arterial lines/catheters (UAC) can support the evaluation of tip placement while potentially reducing the number of necessary X-rays and physical manipulations. Traditional methods often result in scenarios where lines are found to be too high, too low, or malpositioned into the portal system, requiring repeated adjustments. By implementing real-time POCUS, clinicians can visualize the catheter's path and make immediate corrections before the line is secured.

The anatomical path of these catheters is a critical consideration for any clinician performing a scan. A UVC should ideally travel through the umbilical vein, the portal sinus, and the ductus venosus before entering the inferior vena cava (IVC) to rest at the junction of the IVC and the right atrium. In contrast, a UAC takes a different route, moving inferiorly and posteriorly from the umbilicus to join the descending aorta. Understanding these distinct paths allows the practitioner to correctly identify each catheter when the ultrasound probe is placed on the infant’s abdomen.

Technically, POCUS for umbilical lines is most effective when performed as a two-person procedure. While one individual handles the sterile insertion and manipulation of the catheter, a second person performs the ultrasound in real time. It is essential to use a linear probe, as it offers a superior, wider view of the liver, ductus venosus, and portal sinus compared to other probe types. Infection control is maintained by using a sterile cover on the probe, as the scanning occurs near the sterile insertion site with the professional obtaining the images also maintaining sterility.

Confirming the exact location of the catheter tip can sometimes be difficult because the heart is a three-dimensional structure and the tip may not always be clearly visible in a two-dimensional view. To overcome this, clinicians should use multiple views or, sometimes, consider a very small saline flush. By injecting a small amount of saline through the catheter, white dots become visible on the ultrasound screen, confirming the precise location where the fluid exits the tip. Colour mode can also be used to see the injected saline coming out of the tip of the line. These methods are effective for ensuring the catheter has reached the desired junction and has not moved too far into the right atrium. 2D cuts may be tricky as you may be cutting the the catheter proximal to the tip, possibly thinking it is actually the tip. As such, multiple visualization views are important. 

One of the most valuable aspects of real-time POCUS is the ability to troubleshoot malpositions, such as when a UVC enters the right or left portal veins. When a catheter deviates into these veins, it can be pulled back slightly, and gentle pressure can be applied to the right hypochondrium over the liver. This compression can straighten the anatomical path and make the angle into the portal veins more acute, which encourages the catheter to slide correctly into the ductus venosus upon re-insertion. If a catheter is found to be too deep in the heart, it can be pulled back under real-time guidance until the tip is at the optimal junction. From a governance perspective, it is vital to document the procedure by saving ultrasound images and clips. Documentation should include images of the final tip position and, if used, the saline flush to prove the line is intraluminal. Additionally, because umbilical lines are known to migrate during the first few days of life, many units find it beneficial to perform follow-up POCUS scans at 24 to 72 hours to ensure the line remains in a safe position.