Umbilical vein catheterisation is a unique form of central venous access in neonates up to 14 days old.^1,2 The umbilical venous access route is employed in clinical situations where access through the peripheral veins is unobtainable or inappropriate. It is useful in preterm and critically ill neonates who require frequent blood sampling, continuous monitoring of central venous pressure, venous oxygen saturation, administration of intravenous fluids, medications and parenteral nutrition.

Healthcare providers managing neonates should be skilled in multiple techniques of venous access as inaccessibility through the preferred routes may not always be possible in vulnerable neonates.

The umbilical cord develops from the yolk sac and allantois during the fifth week of development within which lies two umbilical arteries and one umbilical vein. The umbilical cord provides a pathway for blood transport from the placenta to the foetus and vice versa.

The average umbilical cord at birth is 2 cm in diameter and 50 cm long. The arteries have a smaller lumen with thick walls and usually do not bleed because of vasospasm.³ The umbilical vein is thin walled with a larger gaping lumen and is usually located at the 12 o’clock position in a cross-section of the umbilical cord (Figure 1).⁴

A catheter inserted and advanced in the umbilical vein should normally move from the umbilical vein into the ductus venosus providing direct access to the inferior vena cava (Figure 2 and Figure 3).^3,5 The relevant anatomic relationships used in the placement of an umbilical catheter is shown in Figure 2b.^6,7

The umbilical veins arise from a convergence of venules that drain the extra- embryonic allantois.

At the end of 6 weeks, the right umbilical vein is obliterated resulting in a single persisting left umbilical vein allowing for the establishment of two pathways through the liver and heart for transport of oxygenated blood from the placenta to the foetus. At birth the intrabdominal umbilical vein is obliterated producing the ligamentum teres.

The indications for umbilical venous catheterisation are:

In a quality improvement study, Shahid et al. developed consensus guidelines for the placement of umbilical venous catheters based on gestational age. They recommended the use of umbilical venous catheters in all preterm neonates with a gestational age of ≤ 28 weeks and neonates ≥ 29 weeks gestation who are on mechanical ventilation or have fractional inspired oxygen (FiO₂) greater than 40% on continuous positive airway pressure or who are haemodynamically unstable.¹⁰ These recommendations were strategies for reducing unnecessary placements of umbilical venous catheters.

Clinically, this procedure may be used in neonates with respiratory distress syndrome, congenital heart disease, haematological diseases and in neonates requiring surgical procedures, nutritional support, fluid resuscitation and haemodynamic monitoring.

The contraindications for placement of umbilical vein catheters include^1,3:

As infusion through the umbilical catheter can only be started when correct placement is certain, it is important to ensure the availability of a confirmatory imaging facility before this procedure is commenced. Catheters placed too deep can lodge in hepatic vessels where medications may cause hepatocellular damage.

The equipment for umbilical venous catheterisation include:

There are polyurethane and polyvinyl umbilical vein catheters that may have single, double or triple lumens. The polyurethane catheters are less prone to bacterial colonisation and are therefore preferred to the polyvinyl catheters.⁵ The use of multiple lumen catheters (double and triple lumen catheters) reduces the need for additional peripherally inserted catheters for simultaneous administration of other infusates or repeated blood samplings. They are, however, more prone to catheter malfunctions.¹¹ In resource poor settings where umbilical vein catheters are not available, size 5 feeding tubes can be used as alternatives.¹²

Obtain informed consent from the parent or guardian for the procedure. The risks, benefits and potential complications of the procedure should be discussed. In emergency situations where this is not possible, consent is implied. Place the neonate in a cot with a radiant warmer, restrained in a supine position (Figure 4)¹⁵ and attach the cardiac monitor and pulse oximetry. Select the appropriate catheter size for the body weight and calculate the estimated length to be inserted. The 3.5 French catheters are used for neonates with body weight less than 3.5 kg while the French 5 catheters are used for neonates who weigh 3.5 kg or more.^5,13,14

Administer 0.1 mL of 33% sucrose solution with a swab orally 2 min before the procedure and repeat the same dose upon commencement of catheterisation.^16,17 Contraindications to the use of oral sucrose for procedural analgesia include sucrose intolerance, fructose intolerance, glucose intolerance and muscle relaxed neonates and infants.

Put on the sterile protective attire. Flush the catheter with heparinised saline and attach to a closed three-way stopcock, which remains closed till the catheter is in the vein. This is to eliminate air from the catheter and prevent clotting. Clean the umbilical stump and abdomen with disinfectant using an outward spiral motion, and cover with sterile drape that leaves the umbilical area exposed.

Apply a loop of umbilical tape or a purse-string suture with silk at the junction of skin and umbilical stump, secure enough to maintain haemostasis but not too tight to prevent passage of catheter. Make a transverse cut completely through the umbilical stump 1 cm to 2 cm from the skin to expose the non-dried umbilical cord and establish a sterile entry surface (Figure 5a). Identify the umbilical vein, cannulate and dilate it with the iris forceps to clear any thrombus in the lumen (Figure 5b). Holding the base of the umbilical stump with the non-dominant hand, insert and advance the catheter in the umbilical vein, cephalad and to the baby’s right side,¹⁸ to the desired length (Figure 5c). Some manoeuvres can enhance the passage of the umbilical vein catheter through the ductus venosus. These manoeuvres include manual mobilisation of the liver during the catheter insertion¹⁹and lying the neonate on the right side to reduce the risk of catheter progression into the portal vein.²⁰ If ultrasound machine and expertise is available, compression of the upper abdomen near the portal sinus of the liver to align the umbilical vein and the ductus venosus during catheter insertion can enhance correct placement.²¹ The catheter has markings on it to measure the desired insertion length. Flush the catheter gently only after blood is aspirated freely (Figure 5d).

The catheter tip position should preferably be confirmed with abdominal ultrasonography⁵ or, where this is not available, with a thoracoabdominal x-ray. Current evidence supports the use of ultrasound for localisation of the umbilical vein catheter. It has been suggested as an ideal modality as it accurately confirms the position of the catheter tip and is associated with a decreased radiation exposure than x-ray. The routine use of point-of-care ultrasound (PoCUS) screening at regular intervals in all newborns with a umbilical vein catheter ensures that the catheter is in the proper position and follows any migration of the catheter and detects any complications.⁷ Adequate training is needed prior to the utilisation of PoCUS and achievement of the required competence is feasible following a very brief training period.²²

The cardiac silhouette and vertebral body methods are used to interpret the thoraco-abdominal x-ray for correct tip position. In the cardiac silhouette method, the curve of the right atrial border is extrapolated medially to its intersection with the inferior vena cava (if catheter is present in it) to determine the target zone, which corresponds to the cavoatrial junction. If the catheter did not pass through the inferior vena cava, the extrapolation is made medially to the right border of the vertebral bodies. In the vertebral body method, the target zone is at the T8–T9 level with the tip lying outside the cardiac silhouette in a lateral X-ray. A well-positioned catheter tip is confirmed if it is in the target zone as estimated by any of the two methods.

The omission of imaging for catheter tip position confirmation may result in failure to detect a catheter tip malposition that carries the risk of morbidities and mortalities from catheter misplacement complications. If the catheter tip position is too high, it should be pulled back to the appropriate position. If the tip position is below the diaphragm, partly withdraw the catheter to the safe short position below the liver or it can be withdrawn completely and a fresh catheter inserted to the appropriate position. Start infusion only when correct placement is confirmed.

It is essential to complete a procedure note in the patient’s file at the end of the umbilical vein catheterisation. The note should include details on the indication for the cathetherisation, date and time of the procedure, means of pain and distress relief, what was performed at every step of the procedure, any complications, estimate of blood loss if any, depth at which the catheter was secured, catheter tip position and how it was confirmed. This procedure note is important for patient follow-up and medico-legal recourse.

A sterile procedure must be used for any manipulation of the umbilical catheter site. The catheter site should be checked every hour,¹⁹ looking for signs of infection (erythema, warmth, swelling). It must be removed if any of these signs are detected, and the neonate started on broad spectrum antibiotics¹⁹ while the catheter tip is sent for culture. The site should be kept clean and dry with regular change of dressing. It should also be checked for bleeding and any change in the functioning of the line.

While umbilical vein catheterisation is a valuable and commonly performed procedure in neonatal care, it is not without risks and complications. The frequency of these complications is not readily available in the literature although several case reports have been published.²³

The possible complications of umbilical venous catheterisation include: