- Category III Fetal Heart Strips: Recurrent Late Decelerations
- Categories of Fetal Heart Tracing
- What Is a Category 3 Fetal Heart Tracing?
- Category 3: Minimal Variability with Recurrent Late Decelerations.
- What Do Late Decelerations Look Like?
- Why Are Late Decelerations Dangerous?
- What Conditions Cause Late Decelerations?
- What Does A Category 3 Strip With Minimal Variability and Recurrent Late Decelerations Look Like?
- Can Recurrent Late Decelerations Be Corrected?
- Doctors and Nurses Have to Stay on Top of the Baby’s Condition
If you are a lawyer with a birth injury malpractice case, you need to be able read fetal heart strips like an obstetrician. Electronic fetal monitoring and the interpretation and reaction to fetal heart strips are a critical focal point in almost every birth injury case. The purpose of this page is to help lawyers and parents better understand how to read fetal heart monitor strips and understand their potential significance when evaluating what went wrong during the delivery process.Categories of Fetal Heart Tracing
Before we read the tracings, it is important to understand the general categories of strips. For a description of these fetal heart tracing categories, please read our summary on Categories of Fetal Heart Tracings.
A Category 3 fetal heart tracing is predictive of an abnormal fetal acid-base status, meaning that the fetus is not getting enough oxygen. Category 3 fetal heart tracings require immediate action and prompt delivery via cesarean section.
There are many different types of Category 3 fetal heart tracing. This page is focused on minimal variability with recurrent Late decelerations.
Unlike a variable deceleration, which appears as an abrupt decrease in fetal heart rate and may not be associated with a contraction, a late deceleration begins after a uterine contraction has started. The fetal heart rate does not return to baseline until well after the contraction has ended. Visually, late decelerations appear very different than variable decelerations. Unlike variable decelerations that look like an upside-down mountain, late decelerations appear as a “U” or “W” shape. They are less abrupt and usually not as pointed. The return to a baseline heart rate is gradual over a period of time. You can see the difference between a late deceleration and variable deceleration below.
Late decelerations are dangerous because they are evidence of utero-placental insufficiency. The placenta is the fetus’ lifeline from the mother. Vital blood and oxygen flow from the mother’s uterus to the placental and into the umbilical cord to the fetus. If there is a disruption in the transfer of blood, nutrients, and oxygen from the uterus to the placenta, the fetus will begin to suffer. Below is an illustration of the fetal placental circulation. As you can imagine, a disruption of this blood flow could severely injure the fetus.
There are many dangerous conditions that can cause late decelerations. A few common ones are as follows:
- Placental abruption
- Maternal diabetes
- Gestational hypertension
- Maternal anemia
- Maternal sepsis
- Post-term pregnancy
- Hyper-stimulated uterus
Whenever late decelerations occur, it is very important for the nurses and physicians to document them in the medical record and to closely follow the patient. If late deceleration begins to occur more frequently, or if they are associated with other fetal heart strip abnormalities, such as minimal variability, the physician may need to perform an emergency cesarean section.
If the doctors and nurses ignore that warning or fail to recognize that periods of minimal variability accompanied by recurrent late decelerations is indicative of abnormal fetal acid-base status and hypoxia, the child runs the risk of a serious birth injury or death.
Late decelerations are “recurrent” when they occur with 50 percent or more of contractions. Late decelerations with minimal variability are a reliable sign of oxygen deprivation. Below is an example of a fetal heart tracing with minimal variability and recurrent late decelerations.
The top portion of the fetal heart strip represents the fetal heart rate, while the bottom portion is the mother’s uterine contractions. As you can see from the tracing, there are late decelerations occurring with every contraction. The decelerations do not begin until after the contraction has started. There is a gradual dip in the fetus heart rate with a return to baseline heart rate after the contraction has stopped. There is minimal beat to beat variability between contractions. The baseline heart rate measured over a 10-minute period is 130 beats per minute.
One thing that is worth noting is that not all late decelerations are created equal. In the example above, there is a prominent late deceleration occurring with the first contraction, while there is a shallow and subtle late deceleration occurring with the second contraction. Unlike variable decelerations, where the depth of the variable deceleration may signal a potential problem, all late decelerations should be treated the same, regardless of how they appear. Even if the late decelerations have different depths, they must be considered dangerous. If they are reoccurring, even with moderate variability in between, it is incumbent upon the nurses and physicians to assess the fetus’s condition.
Sometimes, but it depends. Recurrent late decelerations with moderate variability in between may be caused by excessive uterine contractions or low blood pressure. Sometimes, these conditions can be corrected by reducing the contraction or increasing the blood pressure. This can be done by reducing the Pitocin, providing intravenous fluids, or changing maternal position.
That said, there are some medical conditions, such as diabetes, high blood pressure, and intrauterine growth restriction, where measures to improve the blood flow and oxygen may not be successful. If the lack of oxygen continues, the fetus may develop acidosis and suffer injury. If the fetus is deprived of enough oxygen, the child might go from having late decelerations to no decelerations or bradycardia (low heart rate below 60 beats per minute). Doctors should not wait until this kind of emergency occurs.Doctors and Nurses Have to Stay on Top of the Baby’s Condition
Ultimately, it is the nurses and physician’s responsibility to read and interpret fetal heart tracings, not only by interpreting the tracing, but by considering it in the context of the patient’s condition. A fetal heart strip with moderate variability and recurrent late decelerations (a category 2 strip) could quickly become a category 3 strip with minimal variability and recurrent late decelerations requiring an emergency cesarean section. Most of the time, these fetal heart strips do not miraculously improve. For this reason, it is also important for a physician to consider the mother’s condition. Category 3 fetal heart tracings often occur with diabetic mothers, high risk pregnancies, twin pregnancies, growth restriction, or hypertension. If a patient has one of these conditions, it must be assumed it is the cause of the problem. A patient developing such a pattern in this context may need to be considered for delivery before the tracing becomes any worse. There simply is nothing to be gained by waiting for something bad to happen in this context.