Birth Injury Umbilical Cord Blood Gases and Birth Asphyxia

Interpreting umbilical cord blood gases is crucial at the moment of birth. Umbilical cord blood analysis usually gives an accurate picture of the acid-based balance of the newborn baby. This happens when the umbilical cord is clamped. From the moment of birth and the time of the clamping, the umbilical cord blood remains in continuity with the placenta but will show the progressive change in acid-based status due to ongoing placental metabolism and gas exchange.

According to the National Institute of Health and other authorities, from the moment the umbilical cord is clamped, small changes in umbilical pH occur within 60 seconds of delivery and over 60-minute cord arterial or venous pH can fall by more than 0.2 pH units. Similar changes happen in blood samples from the placental surface vessels except that they are larger and less predictable.

If there is a longer delay in sampling the umbilical cord blood gases, it is important to know whether the sample was taken from isolated cord blood or whether ongoing placental metabolism may have altered the results making them uninterpretable. It is also a known fact that the umbilical blood flow may be restricted before birth. When the umbilical blood flow is restricted, there may be a progressive widening of the difference between umbilical arterial and venous blood gas values. A blood gas sample taken from a newborn shortly after delivery would be expected to show a marked acidosis if there has been an umbilical cord obstruction.

The umbilical vein is larger and easier to sample from than the umbilical artery. Because of fetal carbon dioxides taken from the umbilical arterial blood in the placenta, umbilical venous blood should have a higher pH and lower PCO2 (partial carbon dioxide).

The sampling of umbilical cord blood gases dates back to 1958. It was then recognized that umbilical cord blood gas analysis can give an indication of fetal hypoxic stress. Today, analyzing umbilical cord blood gas has become widely accepted to provide important information about the past, present and possibly the future condition of the newborn baby. Umbilical cord blood gas analysis is generally recommended in any high risk delivery. In some labor and delivery hospitals, analyzing and interpreting umbilical cord blood gases has become routine.

Blood gas samples are taken and analyzed directly for pH, PCO2 and PO2 (partial pressure of oxygen). Bicarbonate (HCO3), base excess (also known as base deficit and the value is a negative) and oxygen saturation are all calculated from the measured parameters.

The difference between umbilical venous and arterial blood gases is rather stark. Blood from the umbilical vein is always determined to have a higher pH than blood in the umbilical arteries.

Blood from the umbilical vein always has a lower PCO2 than blood in the umbilical arteries.

Blood from the umbilical vein always has a higher PO2 than blood in the umbilical arteries.

The analysis of the umbilical cord blood gases may show the normal umbilical cord blood gas range for the venous and arterial averages.

The evaluation of umbilical cord blood gases is to determine fetal acidosis. The pH of umbilical cord blood is determined by the presence of respiratory and metabolic acids. Carbon dioxide diffuses readily within the placenta. The reason for all of this analysis of umbilical cord blood gases is to determine the cause of related fetal oxygen deprivation. The diagnosis of hypoxic ischemic encephalopathy (HIE or birth asphyxiation) can be difficult.

A fetus depends on the mother for oxygen and carbon dioxide exchange. It also relies on the mother for sustenance. In the womb, the fetus does not breathe the way the baby will at birth. Instead, there is a gas exchange in the placenta. The placenta is the organ that connects the developing fetus to the wall of the uterus. The connection between the placenta and the uterine wall allows for nutrients to be exchanged along with the gas exchange by way of the mother’s blood supply. The blood that is oxygenated by the mother then flows into the capillaries in the placenta. The vein in the umbilical cord picks up the oxygenated blood from the capillaries in the placenta and brings it through the baby’s body.

To know whether a baby has suffered oxygen deprivation referred to as anoxic or a hypoxic ischemic event, the best method is to evaluate the umbilical artery blood in that this blood comes from the baby as opposed to going to the baby through the umbilical veins. If it is determined that the umbilical artery blood is acidic or there is acid in the tissues, it suggests that anaerobic metabolism occurred which means that insufficient oxygen was available to the fetus. In that case the baby suffered an anoxic event. On the occasion of anoxic/hypoxic ischemic events, a condition called hypoxic ischemic encephalopathy occurs which may lead to permanent brain damage to the baby. The result of a hypoxic ischemic encephalopathy condition often leads to cerebral palsy or seizure disorders.

This is important because umbilical cord blood gases are often the source of determining whether there was negligence in causing birth trauma or permanent brain damage to a newborn. It is well known that hospitals and physicians and their experts are inclined to defend birth trauma negligence cases by using normal umbilical cord gas results to defeat the case on causation.

There are a variety of good reasons why a fetus who has suffered asphyxia or hypoxia can still have normal umbilical cord blood gases at the moment of birth. For example, the newborn may have had very poor circulation immediately before delivery; the fetus may have had a severe or sudden head injury during delivery that caused the lack of blood flow to the brain or the blood gas results may just simply be invalid due to an error in how the blood was drawn, stored or analyzed. In some of our cases, the blood from the umbilical cord was drawn from the wrong vessel, meaning it was not the artery but the vein or the other way around. It has been reported that as many as 20% of umbilical cord blood gases are simply invalid because of a technician error.

Because the analysis of umbilical cord blood gases at birth are so important, it is imperative that families of babies who have been injured by the negligence of labor and delivery nurses, obstetricians, midwives and other medical practitioners, hire experienced attorneys to evaluate their case.

At Kreisman Law Offices we have more than 40 years of experience handling birth trauma litigation cases for families who have a loved one who has been injured by the negligence of a medical provider. It is vitally important to engage lawyers who understand the long-term expenses associated with a child who has been injured in the labor and delivery process. With our years of experience, we have the know how to correctly evaluate the umbilical cord blood gases and achieve the best results in litigation.

Kreisman Law Offices has been representing parents in birth injury and wrongful death cases caused by the negligence of physicians, hospitals, nurse midwives and other medical providers for more than 40 years.

Kreisman Law Offices provides the best possible services to our clients and have achieved unsurpassed results. Our service is unmatched. Please call us 24 hours a day at 312.346.0045 or toll free 800.583.8002 for a free and immediate consultation, or complete a contact form online. There is no charge for a consultation that will include an evaluation of your case.