Umbilical artery catheter insertion is a common procedure used in intensive care of neonates. It is considered 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 [rarely beyond 7-10 days.]
It allows direct access to the arterial blood supply and allows accurate measurement of arterial blood pressure, serves as a source of arterial blood sampling, and provides intravascular access for fluids and medications.
The umbilical vein, not the umbilical artery, is the preferred route for medication and fluid administration during neonatal resuscitation
The first cannulation of an umbilical artery has been by Dr Virginia Apgar in the 1950s.
The umbilical arteries are the direct continuation of the internal iliac arteries. A catheter passed into an umbilical artery will usually (but not always) enter the aorta via the internal iliac artery may travel to femoral or gluteal arteries too.]
The umbilical artery catheter passes through the umbilicus, travel inferiorly through the umbilical artery, then in the anterior division of the internal iliac artery, into the common iliac artery and then into the aorta
Indications for Umbilical Artery Catheter Insertion
Indications for umbilical artery catheterization include the following:
- Continuous arterial blood pressure monitoring
- Arterial blood gas sampling
- Repeated blood sampling for lab tests
- Exchange transfusion
- Infusion of maintenance fluids when other vascular access is not available
Contraindications for umbilical artery catheterization include the following:
- Cord anomalies
- Necrotizing enterocolitis
- Vascular compromise to the kidneys, buttocks, or lower limb
Procedure of Catheterization of Umbilical Artery
Determination of Catheter Length or Insertion Depth
Before beginning the procedure, determine the insertion depth of the umbilical artery catheter. The depth can be calculated using the following formula [Shukla]
- Umbilical artery catheter depth (cm) = (birth weight [kg] × 3) + 9
Wright et al proposed a slightly different formula, as follows
- Umbilical artery catheter depth (cm) = (birth weight [kg] × 4) + 7
The tip of the catheter should thus be placed in one of two locations:
- high position: at T6 to T10 level
- low position: at L3 to L5 level
Intermediate positions are generally undesirable due to potentially associated thromboses of major aortic branches between T10 to L3.
Umbilical artery catheters placed in the high position are associated with a lower incidence of clinical vascular complications.
Prepare the Catheter
Under sterile condition, connect the three-way stopcock to the end of the catheter. Connect one prefilled 5-mL syringe to each port of the stopcock and flush the system with a heparinized solution. [This can be prepared by one part of 0.45% sodium chloride and one part of heparin.
After ensuring that cath is bubble free, turn the stopcock off.
Prepare the Patient
To avoid limb movements, the small neonates [usually preterm] is placed in soft arm and leg restraints. Larger neonates, if required can be sedated.
Anesthesia is not required because umbilical cord does not have sensory fibers.
The neonate is placed under a radiant warmer in the supine position for adequate thermal support.
Prepare the Insertion Site
Clean the cord and an area of surrounding skin while an assistant holds the stump upright with 4% chlorhexidine gluconate or povidone-iodine solution.
Draping should be done in a manner that adequate exposure to the umbilical cord and base is there and chest and face are out of the sterile field to allow for any immediate resuscitation procedure if needed.
With an umbilical tape, tie a square knot around the base of the cord as close to the abdominal wall as possible. The knot should be tight enough to prevent bleeding when the stump is cut and not overtight to prevent advancement of the catheter or impair blood flow to the skin distal to the tie.
Using no 11 scalpel blade, cut the umbilical stump to within 1-2 cm of the abdominal wall.
Identify and Dilate Umbilical Artery
After cutting, three vessels are seen in the stump. One is large thin-walled umbilical vein and two small umbilical arteries.
Occasionally, only one vein and one artery are present in the umbilical cord
Isolate one umbilical artery, and carefully dilate the lumen. Dilatation is generally done by using Iris forceps. For this, the forceps is inserted as deep as possible and then tips are spread for 20-30 seconds.
With the maneuver being done two or three times, l the lumen of the vessel dilates enough to accept the catheter.
Insert the Catheter
The catheter is held about 1 cm from the tip, with the half-curve Iris forceps while other forceps keep the lumen open and ready for insertion.
Gently insert the catheter into the dilated umbilical artery lumen and advance it.
Remove the half-curve Iris forceps when the catheter has been advanced for about 2 cm.
[If there is resistance, remove the catheter and dilate the vessel again.]
[If vessel spasm is encountered during insertion, 2% lidocaine can be used as a vasodilator. Apply constant pressure until the vessel dilates.]
Advance the catheter to a depth of 4-5 cm. Confirm that it is lumen by aspirating the blood. If blood is easily aspirated, the catheter is within the lumen.
Clear the catheter of blood by flushing with 0.5 mL of heparinized solution.
A resistance to advancement prior to this depth could be due to tight umbilical tie and loosening may help.
A popping sensation while advancing the catheter indicates that catheter has existed in the lumen and created a false track. [confirm by aspiration]
Remove the catheter and use the second vessel for catheterization.
The catheter is advanced to the predetermined depth. Again, the catheter should draw and flush easily to confirm.
If any moment, the vessel spasms, a steady pressure for 30-60 seconds may cause the artery to dilate.
To avoid air embolism during insertion, always withdraw before flushing and carefully observe for bubbles in syringes, tubing, and stopcock.
The placement is confirmed with the chest and abdominal x-ray.
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 and then curving cephalad to enter the aorta and proceeding in a straight line to the left of the vertebral column.
A catheter that has gone to femoral artery or gluteal artery needs to be pulled back as these arteries are not suitable sites for sampling, infusion, or blood pressure monitoring.
After determining the position, secure the catheter with purse string suture through the umbilical cord stump.
An umbilical catheter bridge affixed to the abdominal wall can provide added security.
Remove the umbilical tape after the catheter is secured.
An arterial pressure transducer can be used to and verify a good arterial waveform.
Complications of Umbilical Artery Catheter
- Vessel perforation
- Refractory hypoglycemia
- This often occurs when the catheter is placed near the vessels supplying to the pancreas.
- Glucose-containing fluids when bathing the pancreas cause hyperinsulinemia which leads to decrease in blood glucose levels
- Peritoneal perforation
- Sciatic nerve damage
- Vascular Accidents
- Sequelae of Vascular accidents
- Loss of extremity
- Heart failure (from aortic thrombosis)
- Intestinal necrosis or perforation
- Breakage of catheter
- Necrotizing enterocolitis
- Cotton fiber embolus
- Wharton-jelly embolus
- Air embolism
Removal of Umbilical Artery Catheter
For removal, after stopping the fluid, cut the retention suture, and pull the catheter back to a depth of 1-2 cm.
Then wait for 5-10 minutes to allow the umbilical artery to constrict and then remove the remaining catheter.
Use umbilical tape if there is bleeding.
A pressure applied on iliac artery will control the bleeding. Monitor the child in the supine position for about an hour.
- Shukla H, Ferrara A. Rapid estimation of insertional length of umbilical catheters in newborns. Am J Dis Child. 1986 Aug. 140(8):786-8.
- Wright IM, Owers M, Wagner M. The umbilical arterial catheter: a formula for improved positioning in the very low birth weight infant. Pediatr Crit Care Med. 2008 Sep. 9(5):498-501
- Barrington KJ. Umbilical artery catheters in the newborn: effects of position of the catheter tip. Cochrane Database Syst Rev. 2000. CD000505.
- MacDonald MG, Ramasethu J. Umbilical artery catheterization. Atlas of Procedures in Neonatology. 3rd ed. Philadelphia: Lippincott Williams & Wilkins; 2002. 152-70.