Electronic Fetal Heart Rate Monitoring
What is Electronic fetal heart rate monitoring?
An electronic fetal monitor is a device that uses ultrasound technology to detect the baby’s heart rate. An electronic fetal monitor is actually comprised of two different belts that are placed on the mother’s belly or abdomen when the process beings. The first belt is placed on the top part of the abdomen and is used to detect the baby’s heart rate. The second belt is placed lower down on the woman’s abdomen and is used to detect the contraction pattern.
When mothers go into labor or need to go the hospital for antenatal testing, so that the physicians can check on the wellbeing of the fetus, the mother is often hooked up to a device called an electronic fetal monitor. Electronic fetal monitors are used to determine whether a fetus is being properly oxygenated in utero and gives information concerning a baseline heart rate or the pulse of the baby. It gives information about the variability in the fetal heart rate, and can show when the fetal heart rate dips up, dips down or turns into a concerning pattern.
What are Decelerations?
The dips in the fetal heart rate are often described as decelerations. The monitor can determine three different types of decelerations, late decelerations, variable decelerations and early decelerations.
Early decelerations on an electronic fetal heart rate monitor are generally believed to be from fetal head compression and are often seen when the baby is descending down the birth canal during the labor process itself.
Variable decelerations are just that, they are variable in that they occur in random time periods during the labor process or during an antenatal test. They are often carrot shaped in appearance. They shoot down quickly and will shoot up quickly as well. The variable decelerations are generally thought to be a function of cord compression. The umbilical cord goes from the placenta to the baby’s umbilicus, and transmits blood and oxygen to the baby and away from the mother. If the umbilical cord becomes compressed it can cause the fetal heart rate to variably decelerate.
Late decelerations are a red flag, and are considered dangerous. Late decelerations are termed late because they are late in relation to the contraction. Meaning that after the contraction has already begun, or during the contraction, the baby’s heart rate starts to decelerate. Late decelerations are believed to be from hypoxia or a lack of oxygen and are a function of utero placental insufficiency, meaning the placenta, either because of some defect or clot or just its age, is no longer doing its intended function.
Many years ago, electronic fetal monitor descriptions were broken down into two categories, reassuring fetal heart rate tracings and non- reassuring fetal heart rate tracings.
Reassuring fetal heart rate tracings are indicative of a baby who was properly oxygenated in utero. Then there would be an adequate baseline, good variability, and none of the decelerations, such as late or variable decelerations, which can be concerning.
Non-reassuring tracings meant that the health care provider, typically and obstetrician or nurse midwife, could not be reassured that the baby was doing well in utero, or that the baby was being properly oxygenated in utero. In the setting of non-reassuring fetal heart rate tracings, measures were designed to be undertaken in order to try and correct what was going on and to increase the oxygen to the baby. These measures include turning the mother to one side or the other, giving the mother oxygen and other measures. If those measures proved unsuccessful, a health care provider, such as an obstetrician, or nurse midwife, would be required, under the standard of care, to perform a cesarean section to deliver the baby. The terms reassuring and nonreassuring, although they still appear in medical records, and are still in the obstetrical nomenclature, or are still used by obstetricians across the country, have fallen into disfavor.
3 tiered system
Instead, a three tiered category system has been implemented by the American College of Obstetricians and Gynecologists (ACAG), which is used to dictate what health care providers should do given a certain category. Category 1 tracings are synonymous with reassuring tracings, and Category 3 tracings are consistent with nonreassuring tracings. Category 2 tracings have proven very problematic in the setting of obstetrics, in that health care providers are often unsure about how to act when they are in between Category 1 and Category 2. Unfortunately, the category system, particularly Category 2 tracings, result in health care providers waiting too long to take corrective action in order to rescue a baby who is not doing well in the mother’s womb or in utero.