Umbilical Cord Blood Gas Analysis

While the baby is gestating, the umbilical cord is the all-important lifeline that keeps the fetus alive. Until only recently, it was something that was discarded once the delivery was complete. Now, however, it's also being used to help determine the newborn's condition following a difficult delivery or premature birth. An umbilical cord blood gas analysis can help doctors correctly determine the cause of certain complications at birth.
  1. Abstract

    • After delivery, umbilical cords can be used to determine the pH levels in the newborn's blood. During a difficult labor, the pH levels can be affected by cord compression, excessive contractions or placental malfunction, and this places the infant at risk to immediate and future complications that can lead to death. Such complications include neonatal seizures, serious brain abnormalities and cerebral palsy. By taking a perinatal umbilical blood gas analysis, the doctor is able to determine how the labor affected the infant.

    pH Levels and Acidemia

    • During a difficult birth, it's possible for the newborn's blood pH to drop (the low range for arterial pH is 7.10 and for venous is 7.20 in newborns). This can ultimately lead to the production of lactic acid. It's this production of acid that causes acidemia in newborns, which can ultimately lead to death. Using a blood gas analysis from the umbilical cord allows for a more definitive assessment of the cause and type of acidemia so that the newborn ultimately receives better care.

    APGAR Scores

    • The APGAR test (Activity, Pulse, Grimace, Appearance and Respiration) is given to all newborns immediately after birth. The score ranges from 0 to 2 in the five categories, and infants who score on the lower end of this scale will need a blood gas analysis to help identify the complications that occurred during delivery. This type of analysis works best with pre-term infants because previously low APGAR scores were attributed to asphyxiation during birth rather than an imbalance in pH and acid-base levels.

    In Premature Infants

    • Umbilical cord blood gas analysis is especially important when a child is born prematurely. Premature infants are at a higher risk for complications such as intracranial hemorrhage, cerebral palsy and other neurological problems. A blood gas analysis allows doctors to properly determine the cause of these complications and almost completely eliminates incorrect diagnosis of intrapartum hypoxia or birth asphyxia.

    Protocol

    • Immediately after the birth, clamp the umbilical cord in two locations creating a preserve of blood from the time of birth. From this section of the cord, blood samples are taken from both the artery and vein to get a pH and acid-base reading. Stable readings are able to be determined 60 minutes after the clamping. If there's not enough blood in the umbilical cord, the main artery on the placenta can be used for extraction.

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