Umbilical Artery Catheterization 

The first cannulation of an umbilical artery is attributed to Dr. Virginia Apgar in the late 1950s. Today, umbilical artery catheterization is a common procedure in the neonatal intensive care unit and has become the standard of care for arterial access in neonates. The umbilical artery can be used for arterial access during the first 5-7 days of life, but it is rarely used beyond 7-10 days. The placement of an umbilical artery catheter is easy in principle but often challenging in practice.

Umbilical artery catheterization provides direct access to the arterial blood supply and allows accurate measurement of arterial blood pressure, a source of arterial blood sampling, and intravascular access for fluids and medications.^[1]

• Continuous arterial blood pressure monitoring
• Arterial blood gas sampling
• Blood sampling for other laboratory tests and studies
• Exchange transfusion
• Angiography
• Infusion of maintenance fluids when other routes are not available

• Omphalocele
• Omphalitis
• Cord anomalies
• Peritonitis
• Necrotizing enterocolitis
• Vascular compromise to the kidneys, buttocks, or lower limbs

• Anesthetic agents are not required, as the umbilical cord is devoid of nerve fibers.
• Small preterm neonates can be placed in soft arm and leg restraints to avoid movement during the procedure; anesthesia to prevent struggling is not usually required.
• Full-term and larger preterm neonates can also typically be restrained but may require sedation with intravenous midazolam or fentanyl to decrease struggling.

• Umbilical catheter insertion tray

  • Syringe, 1 mL
  • Syringe, 3 mL (2)
  • Syringe, 5 mL (2)
  • Hypodermic needle, 20 gauge
  • Mosquito hemostat, straight, 5 inch
  • Mosquito hemostat, curved, 5 inch (2)
  • Vessel dilator probe, 5 ½ inch
  • Iris forceps, full curve, 4 inch
  • Iris forceps, half curve, 4 inch
  • Iris forceps, straight, 4 inch, 1 X 2 teeth
  • Straight forceps, smooth
  • Hemostat needle holder, 5 inch
  • Straight Iris scissors
  • Safety scalpel with No. 11 blade
  • Silk suture, 4-0, with curved cutting needle
  • Umbilical tape, 15 inch
  • Measuring tape
  • Drape with 6-cm orifice
  • Gauze pads, 4 x 4 inch (6)
  • Gauze pads, 2 x 2 inch (6)
• Single lumen umbilical artery catheter

  • Catheter, 3.5 F (neonate weight < 1500 g)
  • Catheter, 5 F (neonate weight >1500 g)
• Stopcock, 3-way
• Additional 5-mL syringes (2)
• Heparinized flush (0.45% sodium chloride plus 1:1 heparin)
• Skin preparation solution (4% chlorhexidine gluconate or povidone iodine)
• Sterile surgical towels (4)
• Surgical mask
• Surgical gown
• Sterile gloves
• Arterial pressure transducer

• The neonate should be placed in a supine position under a radiant warmer.
• The head of the neonate should be positioned toward the top of the warmer.
• Care must be taken to ensure adequate thermal support during the procedure, especially in neonates with extremely low birth weight.

Determining catheter depth

Prior to beginning the procedure, determine the insertion depth of the umbilical artery catheter. Various methods have been proposed to accomplish this, and graphs, based on the neonate’s height and weight, have been published.^{[2, 3]} An umbilical artery catheter can be placed in either the high position or the low position, though the high position is associated with lower complication rates.

• In the high position,^[4] the catheter tip lies above the diaphragm, between thoracic vertebrae T6 and T9. This position is above the celiac artery (T12), the superior mesenteric artery (T12-L1), and the renal arteries (L1). For the high position, the insertion depth can be calculated using the following formula: UAC depth (cm) = (weight [kg] X 3) + 9.
• In the low position, the catheter tip lies above the aortic bifurcation (L4-L5) between lumbar vertebral bodies L3 and L4. In this position, the tip of the catheter lies near the origin of the inferior mesenteric artery (L3-L4). According to a recent Cochrane review, no evidence supports the use of umbilical artery catheters placed in the low position.^[5] Umbilical artery catheters placed in the high position are associated with a lower incidence of clinical vascular complications without an increase in any adverse sequelae.

Umbilical artery cannulation

• Before beginning the procedure, restrain the neonate under the radiant warmer using soft arm and leg restraints.
• Prepare the catheter under sterile conditions by connecting the 3-way stopcock to end of the catheter. Connect 1 prefilled 5-mL syringe to each port of the stopcock. Flush the system with heparinized solution (0.45% sodium chloride plus 1:1 heparin). Ensure that no air bubbles are present in the system. Turn stopcock off to catheter.
• An assistant should hold the umbilicus upright with the cord clamp, as shown in the image below, while the physician cleans the cord and an area of surrounding skin (approximately 3-5 cm around cord base) in sterile fashion with 4% chlorhexidine gluconate or povidone iodine solution. Cleansing the umbilical stump.
• Drape the neonate’s abdomen with sterile towels, allowing adequate exposure to the umbilical cord and base.
• Place the umbilical tape at the base of the umbilicus, as shown below. Tie a square knot around the base of the cord as close to the abdominal wall as possible. Tighten the knot securely to avoid bleeding after the umbilical stump is cut. Do not overtighten the umbilical tie, as this makes advancement of the catheter past the knot difficult and may impair blood flow to the skin distal to the tie at the umbilical base. Tying the umbilical cord base.
• Cut the umbilical stump to within 1-2 cm of the abdominal wall using a No. 11 scalpel blade, as depicted below. Use a straight cut across with a gentle sawing motion. Cutting the umbilical cord.
• Identify the vessels in the freshly cut cord (a large, single, thin-walled umbilical vein and 2 small muscular arteries), as shown below. Vessel identification and isolation is made easier by holding the edges of the cord with the curved 5-inch mosquito hemostats. Identification of the umbilical artery.
• Isolate 1 umbilical artery and carefully dilate the lumen using curved Iris forceps, as shown below. Insert the tip of the forceps into the lumen as deeply as possible; then allow the forceps tips to spread open over 15-30 seconds while holding the tips in the vessel lumen. Remove the Iris forceps tips from the lumen and repeat the dilation procedure. Perform the dilation technique 2-3 times until the lumen of the vessel appears dilated enough to accept the catheter. Dilation of the umbilical artery.
• Grasp the end of the catheter, approximately 1 cm from the tip, with the half-curve Iris forceps, as shown below. Hold the vessel lumen open with the full-curve forceps and gently insert the catheter into the dilated umbilical artery lumen. Introduction of the umbilical artery catheter into the vessel.
• Once the catheter is advanced into the lumen to a depth of 2 cm, remove the half-curve Iris forceps. If unable to advance catheter to 2 cm, withdraw the catheter and dilate the vessel again.
• Continue to advance the catheter to a depth of 4-5 cm, and aspirate to verify position in the lumen, as shown below. If blood is easily aspirated, the catheter is within the lumen. Clear the catheter of blood by injecting 0.5 mL of heparinized flush. Aspiration of blood into the umbilical artery catheter to verify intraluminal position.

  • If resistance is met prior to this depth, try to loosen the umbilical tie.
  • If a “popping” sensation is encountered while advancing the catheter, the catheter has likely exited the lumen and created a false tract. If this occurs, remove the catheter and use the second vessel for catheterization.^[6]
• Continue to advance the catheter to the predetermined depth. Once there, again aspirate to verify position in the aorta and flush the catheter. The catheter should draw and flush easily.

  • If resistance is encountered in the first 5 cm during advancement, apply gentle steady pressure for 30-60 seconds to allow the vessel to relax.^[6]
  • If blood is not easily aspirated after insertion, the catheter is likely outside the vessel in a false tract.
• Once the catheter has been advanced to the predetermined depth, confirm placement with a chest and abdominal radiograph. The catheter tip should lie above the level of the diaphragm between thoracic vertebrae T6 and T9.

  • On radiograph, the catheter should be seen entering the umbilical cord and then proceeding inferiorly to connect with the internal iliac artery, as shown below. The catheter should be seen curving cephalad to enter the aorta and proceeding in a straight line to the left of the vertebral column. Correctly positioned umbilical artery catheter with tip at T8-9.
  • If the catheter is noted to be in the femoral artery or gluteal artery, pull the catheter back to a depth of 4-5 cm and attempt reinsertion, as shown below. The femoral and gluteal arteries are not suitable sites for sampling, infusion, or blood pressure monitoring. Umbilical artery catheter incorrectly positioned in left femoral artery.
• Once correct position is verified on radiograph, secure the catheter in place using a purse-string suture through the umbilical cord stump (not through the skin or vessels). This is done in 2-3 bites through the cord in an in-to-out manner. Secure the catheter to the stump by wrapping the tails of the suture snugly around the catheter and then tying securely with a surgical instrument tie, as depicted in the images below. Securing suture in the umbilical stump. Securing suture in the umbilical stump looped around the umbilical catheter and tied securely in place.
• Further secure the catheter by way of a self-made or commercially available umbilical catheter bridge adhered to the abdominal wall, as shown below. Tape bridge placed to secure umbilical catheters in place.
• Loosen and remove the umbilical tape once the catheter is secured.
• Connect the arterial pressure transducer and verify good arterial wave form.
• To remove the umbilical artery catheter, stop fluid infusion, cut retention suture, and pull the catheter back to a depth of 1-2 cm. Wait at least 5-10 minutes to allow the umbilical artery to constrict before removing the catheter. Use umbilical tape secured around the base of the cord if bleeding occurs. Alternatively, pressure can be applied to the iliac artery to control bleeding. Keep the neonate supine for 30-60 min after umbilical artery catheter removal to allow easy monitoring of bleeding.

• Fold drapes so as not to obscure neonate’s face and upper chest. This allows an assistant access to the neonate’s airway in case of emergency and allows visualization of chest rise and work of breathing during the procedure.
• Avoid false-tracking the catheter. Make sure the catheter is in the lumen of the vessel, not in the wall.
• Take time to dilate the vessel. This increases the likelihood of success and decreases the chance of exiting the vessel and causing a false tract.
• The catheter should never be forced. If advancing the catheter is difficult within the first 2-4 cm, check that the umbilical tape is not too tight. Also, the entire cord can be pulled toward the neonate’s head to facilitate passage of the catheter at the angle between the cord and the abdominal wall.^[6]
• If the vessel spasms, apply slow steady pressure for 30-60 seconds to allow the artery to dilate.
• If vessel spasm is encountered during insertion, 2% lidocaine hydrochloride without epinephrine can be used as a vasodilator.^[6] To apply, insert the catheter 2 cm into the vessel lumen and then drip 0.5 mL of lidocaine into the vessel. Apply constant pressure until the vessel dilates.
• To avoid air embolism during insertion, always withdraw before flushing and carefully observe for bubbles in syringes, tubing, and stopcock.
• Never advance a catheter once placed and secure. This greatly increases the risk of infection by introducing a length of contaminated catheter into the vessel.^[6]
• Placing a radiograph plate under the neonate before beginning the procedure avoids having to move the neonate to place film once the catheter is in place.
• The umbilical vein, not the umbilical artery, is the preferred route of medication and fluid administration during neonatal resuscitation. For more information, see eMedicine article Catheterization, Umbilical Vein and Medscape’s Resuscitation Resource Center.

Malpositioned catheter

• Vessel perforation
• Refractory hypoglycemia (if infusing glucose-containing fluids and catheter tip near celiac axis)
• Peritoneal perforation
• Sciatic nerve damage

Vascular accident

• Thrombosis^[7]
• Embolism/infarction
• Vasospasm
• Loss of extremity
• Hypertension
• Paraplegia
• Heart failure (from aortic thrombosis)
• Air embolism

Equipment-related

• Broken catheter
• Transection of catheter^[8]

Other

• Hemorrhage
• Infection^[9]
• Necrotizing enterocolitis
• Intestinal necrosis or perforation

  • Vascular accident
  • Infusion of hypertonic solution
• Cotton fiber embolus
• Wharton-jelly embolus
• Hypernatremia (true or factitious)