Umbilical Artery Catheterization Technique

Updated: Feb 24, 2017
  • Author: Taylor L Sawyer, DO, MEd, FAAP, FACOP; Chief Editor: Vincent Lopez Rowe, MD  more...
  • Print
Technique

Catheterization of Umbilical Artery

Determining catheter depth

Before 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 by using the following formula, developed by Shukla [3] :

  • Umbilical artery catheter depth (cm) = (birth weight [kg] × 3) + 9

Wright et al proposed a slightly different formula, as follows [5, 6] :

  • Umbilical artery catheter depth (cm) = (birth weight [kg] × 4) + 7

Gupta et al described an alternative approach that relied on morphometric measurements—specifically, the distances from umbilicus to nipple (UN) and from umbilicus to symphysis pubis (USp)—to determine insertion length, rather than on birth weight. [7]  They found that the formula (UN – 1 cm) + 2USp was better correlated with appropriate umbilical artery catheter insertion length than the Shukla formula was (92% estimated correct insertion length vs 57%); this formula was also more accurate in very low birth weight infants than the Wright formula was (94% vs 68%).

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 Cochrane review, no evidence supports the use of umbilical artery catheters placed in the low position. [8]  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 three-way stopcock to the end of the catheter. Connect one 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 the stopcock off to the catheter.

An assistant should hold the umbilicus upright with the cord clamp (see the image below) while the physician cleans the cord and an area of surrounding skin (~3-5 cm around the cord base) in sterile fashion with 4% chlorhexidine gluconate or povidone-iodine solution.

Umbilical artery catheterization. Cleansing of umb Umbilical artery catheterization. Cleansing of 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 (see the image 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, because 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.

Umbilical artery catheterization. Tying of umbilic Umbilical artery catheterization. Tying of umbilical cord base.

Cut the umbilical stump to within 1-2 cm of the abdominal wall using a No. 11 scalpel blade (see the image below). Use a straight cut across with a gentle sawing motion.

Umbilical artery catheterization. Cutting of umbil Umbilical artery catheterization. Cutting of umbilical cord.

Identify the vessels in the freshly cut cord (one large thin-walled umbilical vein and two small muscular arteries). (See the image below.) Vessel identification and isolation are made easier by holding the edges of the cord with the curved 5-in. mosquito hemostats.

Umbilical artery catheterization. Identification o Umbilical artery catheterization. Identification of umbilical artery.

Isolate one umbilical artery, and carefully dilate the lumen using curved Iris forceps (see the image 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 two or three times until the lumen of the vessel appears dilated enough to accept the catheter.

Umbilical artery catheterization. Dilation of umbi Umbilical artery catheterization. Dilation of umbilical artery.

Grasp the end of the catheter, approximately 1 cm from the tip, with the half-curve Iris forceps (see the image below). Hold the vessel lumen open with the full-curve forceps, and gently insert the catheter into the dilated umbilical artery lumen.

Umbilical artery catheterization. Introduction of Umbilical artery catheterization. Introduction of umbilical artery catheter into vessel.

Once the catheter is advanced into the lumen to a depth of 2 cm, remove the half-curve Iris forceps. If it is not possible to advance the catheter to 2 cm, withdraw it 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 (see the image 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.

Umbilical artery catheterization. Aspiration of bl Umbilical artery catheterization. Aspiration of blood into 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. [9]

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. [9]

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 chest and abdominal radiography. The catheter tip should lie above the level of the diaphragm between T6 and T9.

On radiography, the catheter should be seen entering the umbilical cord and then proceeding inferiorly to connect with the internal iliac artery (see the image 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.

Umbilical artery catheterization. Correctly positi Umbilical artery catheterization. Correctly positioned umbilical artery catheter with tip at T8-9.

If the catheter is found to be in the femoral artery or gluteal artery, pull it back to a depth of 4-5 cm and attempt reinsertion (see the image below). The femoral and gluteal arteries are not suitable sites for sampling, infusion, or blood pressure monitoring.

Umbilical artery catheterization. Umbilical artery Umbilical artery catheterization. Umbilical artery catheter incorrectly positioned in left femoral artery.

Once correct positioning is verified on radiography, secure the catheter in place using a purse-string suture through the umbilical cord stump (not through the skin or vessels). This is done by taking two or three 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 (see the images below).

Umbilical artery catheterization. Securing suture Umbilical artery catheterization. Securing suture in umbilical stump.
Umbilical artery catheterization. Securing suture Umbilical artery catheterization. Securing suture in umbilical stump looped around umbilical catheter and tied securely in place.

Further secure the catheter by means of a self-made or commercially available umbilical catheter bridge affixed to the abdominal wall (see the image below).

Umbilical artery catheterization. Tape bridge plac Umbilical artery catheterization. Tape bridge placed to secure umbilical catheters in place.

Once the catheter is secured, loosen and remove the umbilical tape. Connect the arterial pressure transducer, and verify a good arterial waveform.

To remove the umbilical artery catheter, stop fluid infusion, cut the 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. If bleeding occurs, use umbilical tape secured around the base of the cord. Alternatively, pressure can be applied to the iliac artery to control bleeding. Keep the neonate supine for 30-60 minutes after umbilical artery catheter removal to allow easy monitoring of bleeding.

Procedural pearls

Fold drapes so as not to obscure the 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. [9]

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. [9]  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 it is placed and secure. Doing so greatly increases the risk of infection by introducing a length of contaminated catheter into the vessel. [9]

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 for medication and fluid administration during neonatal resuscitation. For more information, see the Resuscitation Resource Center, as well as Umbilical Vein Catheterization.

Next:

Complications

Complications of umbilical artery catheterization that are related to catheter malpositioning include the following:

  • Vessel perforation
  • Refractory hypoglycemia (if glucose-containing fluids are being infused and the catheter tip is near the celiac axis)
  • Peritoneal perforation
  • Sciatic nerve damage

Complications related to vascular accidents include the following:

  • Thrombosis [10]
  • Embolism/infarction
  • Vasospasm
  • Loss of extremity
  • Hypertension
  • Paraplegia
  • Heart failure (from aortic thrombosis)
  • Air embolism

Equipment-related complications include the following:

  • Broken catheter
  • Transection of catheter [11]

Other complications include the following:

  • Hemorrhage
  • Infection [12]
  • Necrotizing enterocolitis
  • Intestinal necrosis or perforation (related to a vascular accident or infusion of hypertonic solution)
  • Cotton fiber embolus
  • Wharton-jelly embolus
  • Hypernatremia (true or factitious)
Previous