Intrapartum assessment - Fetal heart rate patterns: Nursing

Intrapartum assessment of the fetal heart rate, or FHR for short, refers to the assessment of the FHR and rhythm in response to uterine activity during the intrapartum period, which refers to the time of pregnancy from the onset of labor to delivery of the newborn and the placenta. Now, fetal monitoring can be external or internal. External fetal monitoring is a noninvasive method to monitor the FHR and uterine activity. An ultrasound transducer is placed on the maternal abdomen over the fetal back to record the FHR. A tocotransducer, sometimes called a tocodynamometer, or toco for short, is a pressure-sensitive button that is placed over the uterine fundus to track uterine activity. Both devices are held in place by belts or bands and then attached to the fetal monitor that can print out or display the FHR and uterine activity.

Now, during the procedure, the client should avoid the supine position because the weight of the uterus and fetus can compress large blood vessels, such as inferior vena cava and aorta. This can decrease cardiac output and cause supine hypotension, which results in less blood pumping into the systemic circulation and the placenta, so less oxygen is delivered to the fetus. To alleviate the pressure on these vessels, the client should be turned to a lateral recumbent position, or a wedge should be placed under the right hip, displacing the uterus to the left and away from the vessels. On the flip side, internal fetal monitoring is an invasive procedure that requires cervical dilation of at least 2 to 3 centimeters and rupture of the fetal membranes. This way, a spiral electrode can be placed through the cervix onto the presenting part of the fetus, most commonly the scalp, to track the FHR.

If uterine contractions also need to be monitored more closely, an intrauterine pressure catheter can be placed inside the uterus.Now, let’s take a look at the fetal heart rate tracing, which is divided into two main parts. The upper part records the FHR, while the lower part records the uterine activity. At the bottom of each part, there’s an X axis which represents the time, while the Y axis on the left, measures the fetal heart beats per minute, as well as the relative strength of a uterine contraction, measured in millimeters of mercury. Now, there are several important parameters that we assess when looking at the FHR. These include the baseline FHR, variability, and periodic changes. First, let’s take a look at the baseline FHR, which refers to the average FHR, meaning it does not include other variables, such as marked variability, periodic changes, or segments with a difference greater than 25 beats per minute.