Cord blood gas analysis determines the fetal metabolic condition when umbilical circulation stops during childbirth.
Clamping the umbilical cord is standard procedure when a baby is born. Studies have shown that this is vital to determining the baby’s health.
Umbilical cord blood gas analysis helps doctors detect if the child suffered a birth injury during delivery. Cord blood gases show whether or not a baby is experiencing acidosis, which can indicate that there was a hypoxic-ischemic event.
The results from cord blood gases are frequently used as evidence in medical malpractice lawsuits by both attorneys and doctors as a marker for the harm done to the child and to prove whether negligence was involved in a child’s injury.
When our birth injury lawyers are discussing a new case that has come into our office, one of the first questions is about the child’s cord blood gas values. But you do not need to have a malpractice lawsuit to want to understand your child’s blood gas values better and what they mean.
If you have a potential birth injury lawsuit anywhere in the United States, call us at 800-553-8082 or get an online case review.
What Are Cord Blood Gases?
To understand what cord blood gases are, it’s helpful to know how the placenta supplies oxygen and nutrition to a baby in the womb. A fetus relies on the mother for oxygen and carbon dioxide exchange. A developing baby does not breathe like it would after birth.
The placenta uses gas exchange to supply them with oxygen that comes from the mother’s blood. After the mother’s blood is oxygenated, it is absorbed by the placenta’s capillaries.
The capillaries will then deliver the blood to the placenta’s main artery, which is finally transferred to the baby.
Why Are Core Blood Gases Important to Access a Newborn?
When the baby is born, the umbilical artery briefly retains information about the baby’s condition, referred to as blood cord gases. Doctors clamp the umbilical cord within seconds after birth to measure acidity inside the umbilical artery.
The question is how much oxygen the baby was getting. Analyzing cord blood gas levels is often the best indicator of hypoxia or ischemia during delivery.
Cord gas interpretation can show how healthy the baby is and determine whether it has a birth injury.
Accurate results are also essential. This is why the cord must be clamped quickly. Waiting even 45 seconds will skew the results due to chemicals changing in the artery.
What Is Base Excess?
The base deficit is calculated using measured blood levels for acid (pH), dissolved carbon dioxide gas (PCO2), and bicarbonate HCO. It is these values that describe the baby’s metabolic state.
How Do You Draw Umbilical Cord Blood?
The doctor clamps the umbilical cord quickly after childbirth. A needle withdraws blood from the cord. Again, this must be done quickly to get reliable umbilical cord blood gas results.
How Are Blood Cord Gases Measured?
The most critical measurements in arterial cord blood gas examination are the baby’s pH levels and base deficit. Both are used to determine the acidity level in the umbilical cord.
The levels determine if the baby has acidosis, a condition caused by the overproduction of acid in the blood. Acidosis usually presents itself as decreased blood pH and increased base deficit. If a baby has acidosis, you will see poor cord gases at birth. It is a red flag that indicates the presence of hypoxia during delivery.
What Are Normal Arterial Blood Gases Values?
Cord blood interpretation can be complex. But these baseline values give you some indication of where there could be a problem.
Normal arterial blood cord gas values in a full-term newborn:
| Parameter | Value | Units |
| Mean pH | 7.28 ± 0.07 | N/A |
| Mean PCO2 (carbon dioxide) | 49.9 ± 14.2 | mmHg |
| Mean PO2 (oxygen) | 23.7 ± 10.0 | mmol/L |
| Mean base deficit | -3.6 ± 2.8 | mmol/L |
Normal blood cord gas levels in a preterm newborn are similar but different:
| Parameter | Value | Units |
| Mean pH | 7.29 ± 0.07 | |
| Mean PCO2 | 49.2 ± 9.0 | mmHg |
| Mean PO2 | 23.6 ± 8.9 | mmol/L |
| Mean base deficit | -3.3 ± 2.4 | mmol/L |
All values are ± 1 standard deviation. The “P” in PO2 and PCO2 means “partial pressure, ” which is how the cord blood gases are measured. PCO2 measures the amount of carbon dioxide gas dissolved in the blood, and PO2 measures the amount of oxygen in the blood.
Why Are PH Levels Important?
Cord pH provides a critical measurement of the baby’s acid-base status when the cord is cut. This gives a good window into the fetus’s oxygenation status in the immediate period leading up to delivery.
A normal arterial pH in a newborn suggests adequate oxygenation and perfusion during labor and delivery. Conversely, a low pH (acidosis) can indicate that the baby experienced hypoxia (reduced oxygen supply) or ischemia (reduced blood flow) at some point before, during, or after delivery.
The data shows that pH levels at birth are pretty good – but not perfect at predicting how well the child does. Severe acidosis is associated with higher risks of neonatal morbidity, such as neurological impairment, and in severe cases, mortality. Monitoring pH can help identify newborns at risk of adverse outcomes, allowing for timely intervention and close monitoring.
Remember that cord blood gas analysis is safe for the child.
How to Interpret PO2 Levels?
A PO2 level at birth can be an essential indicator in neonatal care. The partial pressure of oxygen in the arterial cord blood reflects the amount of oxygen in the blood at birth. This measurement is taken from the umbilical cord immediately after delivery.
PO2 is typically assessed as part of a larger arterial blood gas (ABG) analysis, which will also include pH, carbon dioxide pressure (PCO2), bicarbonate (HCO3), and base excess. This comprehensive approach helps assess respiratory and metabolic function in the newborn.
High PO2
Elevated PO2 levels at birth may indicate over-oxygenation of the fetus. While oxygen is critical for survival, too much oxygen can be harmful, especially for premature infants. So a high PO2 in the arterial cord blood of a newborn can indicate that the baby was receiving a higher-than-normal amount of oxygen before birth. Excessive oxygen exposure can lead to conditions like retinopathy of prematurity (ROP) and oxidative stress, which can cause cellular damage.
If high PO2 levels are detected, medical professionals will assess the newborn’s overall health and oxygenation status. The goal is to maintain PO2 within a target range that supports adequate oxygenation without reaching levels high enough to cause oxidative damage. Management will depend on the underlying cause and the baby’s condition. It might include adjusting respiratory support (if provided) and carefully monitoring oxygen levels.
Low PO2
A PO2 level significantly below the expected range for their gestational age and minutes or hours post-birth might indicate hypoxemia. In newborns, hypoxemia can be due to various reasons like respiratory distress syndrome, congenital heart defects, lung fluid, or inadequate lung expansion.
Metabolic acidosis, where the pH is low but PCO2 is normal or low, suggests a metabolic problem. It might indicate conditions like infection, inadequate perfusion leading to lactic acid buildup, or other metabolic disorders.
Like any other test on a newborn, neonatal PO2 levels must be interpreted in the context of the baby’s overall health, including respiratory effort, skin color, and other vital signs. Other factors, such as the method of oxygen delivery (if any) and the location’s altitude, should also be considered.
How Does Acidosis Affect My Baby?
Acidosis has two different types: respiratory acidosis and metabolic acidosis. Respiratory acidosis refers to high acid levels caused by impaired lung function, leading to retained carbon dioxide in the lungs and bloodstream.
Metabolic acidosis occurs when the body’s acid levels are high due to impaired kidney function. Both forms of acidosis can cause neurological issues that can be temporary or permanent, depending on the severity of the damage. In general, however, metabolic acidosis is associated with more adverse outcomes.
How do you calculate acidosis? Low blood pH and high base deficit indicate acidosis, which can be calculated from pH, CO2 pressure, and hemoglobin levels.
Low pH levels caused by acidosis can result in hypoxic-ischemic encephalopathy, periventricular leukomalacia, seizures, brain hemorrhages, and cerebral palsy. In severe cases of metabolic acidosis, it can lead to multi-organ failure and even death.
The primary cause of acidosis is insufficient oxygen from the placenta to the baby.
Blood Cord Gases in Medical Malpractice Lawsuits
Blood cord gas results can be used as an essential piece of evidence in birth injury litigation. If a baby suffered from hypoxia that resulted in a birth injury, the blood cord gases can prove the legitimacy of the plaintiff’s claim.
Malpractice lawyers and medical experts can also interpret blood cord gas levels to show the severity of damage during delivery by citing the specific pH and base deficit levels.
However, doctors can also use blood cord gases to defend against birth injury lawsuits as well. If the baby has a birth injury but their blood cord gases come back normal, the obstetrician can use the umbilical cord gas levels as evidence that the injury did not occur during delivery and was not caused by negligence.
There are many reasons why a baby would have normal blood cord gases despite suffering from a hypoxic brain injury. The baby might have had poor circulation and perfusion shortly before being born, or they could have experienced a physical head injury during delivery.
There may have been an error in storing and analyzing the blood. According to one study, up to 19% of blood cord gas samples are invalid due to human error. There are also blood cord gas interpretation errors that inflate or deflate the child’s hypoxia at birth.
A medical malpractice attorney must be skilled in medical knowledge about pH and base deficit levels to prevail in a birth injury lawsuit involving blood cord gases.
They should take the time to examine the process of taking blood cord gas samples and identify any possible technical errors that make the results invalid. Birth injury lawyers also need to work closely with a medical expert to prove the cause and timing of the birth injury.
Do Abnormal Cord Blood Gases Mean My Child Has a Brain Injury?
Abnormal cord blood gas results are a marker for a birth injury. But abnormal fetal cord blood gas results do not mean that your child has a brain injury. Many children with troubling cord blood gas and APGAR results have no long-term physical or cognitive deficits.
Hiring a Birth Injury Lawyer
Are you confused about what happened to your child? Miller & Zois can help. Call us at 800-553-8082. You will speak with a nurse attorney who will understand what has happened to you. We will explain your compensation options and answer any questions you may have. You can also get an online case review.