What is a normal umbilical cord blood gas level?
As soon as a baby is born, the medical team usually draws blood from the baby’s umbilical cord artery. Umbilical cord blood is analyzed to determine if there was a complication shortly before or during delivery that deprived the baby of oxygen. Oxygen deprivation can cause serious birth injuries such as hypoxic-ischemic encephalopathy (HIE), intraventricular hemorrhages (brain bleeds), cerebral palsy (CP) and seizure disorders.
What are “normal” umbilical cord blood gas levels?
Normal arterial cord blood gases for a term newborn:
- pH: 7.18 – 7.38
- PCO2: 32 – 66 (mmHg)
- HCO3-: 17 – 27 (mmol/L)
- PO2: 6 – 31 (mmHg)
- Base excess (BE): -8 – 0 (mmol/L); (Base deficit (BD): 0 – 8)
Normal arterial cord values in a preterm newborn:
- pH: 7.14 – 7.4
- PCO2: 32 – 69 (mmHg)
- HCO3-: 16 – 27 (mEq/L)
- BE: -7.6 – 1.3 (mmol/L); (BD: 1.3 – 7.6)
Note: The “P” in PCO2 and PO2 stands for “partial pressure,” which is how these gases are measured.
How should arterial cord blood gas values be interpreted?
The key point for parents to know is that pH and BE/BD are the main values examined by the medical team. The other values impact pH and BE, but pH and BE are the main numbers examined to determine if your baby suffered from a lack of oxygen to the brain either shortly before or during delivery.
pH
A low arterial cord pH is probably the single most important value used to determine if hypoxia near the time of delivery was severe enough to cause hypoxic-ischemic encephalopathy (HIE). If pH is low, the medical team should be alert to the fact that your baby may have sustained HIE or another brain injury. A pH below 7.18 for a term infant is considered abnormally low, but research shows a strong association between a pH of less than 7.0 – 7.24 and adverse outcomes (such as HIE, brain bleeds, PVL and cerebral palsy) in babies.
Base Excess/Base Deficit
Base deficit (a negative base excess) is defined as the amount of strong base that must be added to return pH to normal values. The more negative a BE, the greater the concentration of metabolic components that contributed to acidic (low) pH. The more abnormally negative the base excess, or the larger the base deficit, the more serious the acidosis. The greater the acidosis, the more serious the oxygen deprivation was in the baby (in most cases). Although anything more negative than -8 is considered an abnormally low BE, most research shows that a BE equal to or more negative than -12 (or BD of 12 or more) is a predictor of complications in the newborn.
What if my baby has a normal BE/BD and pH values?
Normal BE/BD and pH do not rule out the fact that the baby experienced oxygen deprivation before or during delivery. There are a number of reasons a baby may have a normal BE and pH, but still have experienced birth asphyxia.
For example, a baby may have suffered a very severe – even total – oxygen depriving event right before birth. This can occur in cases of complete placental abruption and complete umbilical cord occlusion. In these instances, there may not be enough time for the cardiopulmonary system to reflect the oxygen deprivation that occurred, yet the deprivation could be severe enough to cause brain injury. In other instances, the baby’s circulation and blood flow are so poor that the acid products from anaerobic metabolism do not move through the baby’s body via normal circulation and blood flow. Therefore, they would not be reflected in the umbilical cord arterial blood gas sample.
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What causes abnormal cord blood gas values?
Abnormal cord blood gas values can be caused by a variety of factors — labor complications, fetal presentation, placental function — all of which can lead to the baby being deprived of oxygen.
During labor and delivery, the baby’s heart rate should be closely monitored with a fetal heart monitor. If the baby starts to experience oxygen deprivation, non-reassuring heart tracings will appear on the monitor. In most cases, when these tracings occur, the baby must be delivered immediately by emergency C-section delivery.
Permanent brain injury from oxygen deprivation often occurs when medical staff fails to promptly act on non-reassuring heart tracings and indications of fetal distress. This failure to act can cause the baby to be left in oxygen-depriving conditions for too long.
Can babies with abnormal blood gas values still be healthy and have no brain damage?
Yes, the presence of abnormal umbilical cord blood gas results does not necessarily mean a baby will have a permanent brain injury. If a baby has HIE, immediate intervention in the form of hypothermia treatment can minimize the damage. Other interventions can also help to prevent or limit lifelong injuries, such as:
- Prompt and appropriate resuscitation at birth
- Proper management of your baby’s breathing, heart rate, blood pressure and circulation
- Timely treatment of potential seizures, hypoglycemia, and jaundice
Addressing neonatal problems in a timely manner can prevent them from becoming a permanent injury.
About ABC Law Centers: Birth Injury Lawyers
ABC Law Centers was established to focus exclusively on birth injury cases. A “birth injury” is any type of trauma to a baby that occurs just before, during, or after birth. While some children with birth injuries make a complete recovery, others develop disabilities such as cerebral palsy, hypoxic-ischemic encephalopathy and epilepsy.
If a birth injury or a related disability could have been prevented with proper care, this is medical malpractice. Your child could have their lifelong treatment, care, and other crucial resources covered by a birth injury case settlement.
If you believe negligence occurred during your labor and delivery, contact us today. We are available 24/7 to hear your story and answer your questions free of any obligation or charge. We are here to listen – even if you decide not to pursue a legal case with us! If you do, you would pay nothing throughout the entire legal process unless we win.
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