16.2 External and Internal Monitoring

Intermittent Auscultation

The technique of assessing fetal well-being by listening to and counting the fetal heart rate for a specified amount of time and at specified intervals, depending upon the stage of labor, is called intermittent auscultation (IA). The nurse palpates the uterus to evaluate the contractions’ duration (from the beginning to the end of the contraction), intensity, and frequency (from the beginning of one contraction to the beginning of the next contraction). The nurse listens before, during, and after the contraction to evaluate for any FHR changes. The nurse may perform IA with either a fetoscope or a Doppler monitor. The fetoscope is similar to a stethoscope but also uses bone conduction to allow for better detection of the FHR. The fetoscope can be used after 20 weeks’ gestation; prior to that time, the FHR is not detectable by fetoscope. A Doppler monitor is a handheld device that uses ultrasonic waves to detect the FHR. Dopplers are used in antepartum visits as well as during labor. When auscultating the FHR, it is important to assess the maternal heart rate at the same time to ensure the Doppler is providing fetal data.

Determining Optimal Placement of the Auscultation Device Using Leopold’s Maneuvers

Determining the position of the fetus is important when placing the ultrasound transducer or fetoscope on the abdomen of the laboring person. Leopold’s maneuvers are performed to assist in identifying the fetal position. The nurse performs the maneuvers, locates the fetal back, and then places the transducer on the laboring person’s abdomen directly over the fetal back where the fetal heart is the loudest. Figure 16.16 illustrates where to hear the FHR most clearly when the fetus is vertex or breech. Figure 16.17 illustrates Leopold’s maneuvers to determine the fetal presentation and position.

Figure 16.16 Listening to the FHR The FHR is heard loudest over the fetal back. (a) If the nurse hears the FHR loudest in the lower abdomen, the fetus is most likely vertex. (b) If the FHR is the loudest above the umbilicus, the fetus is most likely breech. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

Figure 16.17 Leopold Maneuvers (1) Facing the patient, both hands palpate the top of the abdomen to determine the shape, mobility, and size of the fetal part. (2) After determining what is in the fundus, the hands slide down to the sides of the uterus and determine the fetal lie. (3) To determine the presenting part of the fetus in the pelvic inlet, the hand is held in a “C,” and the thumb and fingers grasp the fetal part in the low abdomen above the pubic bone. (4) To determine the fetal attitude and degree of descent into the pelvis, while the nurse is turned to face the laboring person’s feet, both hands palpate down the sides of the uterus to the pubic bone and presenting part. (credit: “Handgriffe” by Christian Gerhard Leopold/Wikimedia Commons, Public Domain)

The nurse explains to the patient that these maneuvers require touching of the abdomen to discover how the fetus is lying inside the uterus. The nurse will lower the head of the bed with the patient on their back and begin the assessment.

• The first maneuver is done facing the patient. Both hands palpate the top of the abdomen to determine the shape, mobility, and size of the fetal part. A hard, round fetal part is the head and would diagnose the fetal position as noncephalic. A larger, softer fetal part is the buttock or back of the fetus.
• The second maneuver is used to determine the placement of the fetal back. After determining what is in the fundus, the hands slide down to the sides of the uterus and determine the fetal lie. If the nurse determines the fetal lie is longitudinal (or oblique), using the palms, the right hand holds the uterus while the left palpates for a smooth long back or small, “bumpy” extremities. The opposite side is then palpated. If the nurse determines the fetal lie is transverse, the nurse will palpate the fetal head on one side and lower extremities on the opposite side. The fetal back will face either the fundus or the cervix.
• The third maneuver determines the presenting part in the pelvic inlet. Holding the hand in a “C,” the thumb and fingers grasp the fetal part in the low abdomen above the pubic bone. Again, if the part is hard and round, it is the fetal head. The nurse can attempt to move the head back and forth to determine if the head is engaged in the pelvis.
• The fourth and last maneuver is used to determine the fetal descent into the pelvis. Turning to face the laboring person’s feet, both hands palpate down the sides of the uterus to the pubic bone and presenting part. The brow cannot be palpated if the fetal head is well flexed and engaged.

After performing the Leopold maneuvers and determining the placement of the fetal presentation and back, the nurse places the ultrasound transducer or Doppler to assess FHR.

Continuous External Monitoring of FHR and Contractions

The most common method of monitoring the fetal heart rate and contraction pattern is through continuous external monitoring. Doing so requires the use of two monitoring devices: an ultrasound device to evaluate the fetal heart rate, and a tocodynamometer (toco) to detect the frequency of uterine contractions. The nurse applies these external monitors to the patient’s abdomen; the devices are held in place with belts or adhesives. Figure 16.18 shows the continuous fetal monitor and the wireless fetal monitoring system. Wireless monitors allow patients to ambulate in labor. Other monitors are waterproof and allow for continuous monitoring during hydrotherapy and water birth.

Figure 16.18 Continuous and Wireless Fetal Monitoring Systems (a) Continuous external monitoring uses an ultrasound device to evaluate the fetal heart rate and a tocodynamometer to detect the frequency of uterine contractions. (b) A wireless fetal monitoring system allows freedom of movement for the laboring person. The patch with the arrow monitors the contraction frequency and length. The remaining patches monitor the fetal heart rate. The blue box is the wireless connection. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

Both transducers are connected to the monitor, and their signals are traced onto graph paper. The nurse explains to the patient that these monitors are external and can lose the signal with movement of the laboring person or fetus. The nurse explains that the laboring person should not be alarmed if they no longer see the signal on the monitor. They are instructed to call the nurse in these instances so that the monitor can be adjusted.

Through continuous external monitoring, fetal heart rate baseline and variability can be determined, as can periodic fetal heart rate changes. Situations requiring continuous fetal monitoring include meconium-stained fluid, multiple gestation, preeclampsia, epidural or spinal anesthesia, and dysfunctional labor (Simkin et al., 2017).

Application of the External Monitors

Uterine and FHR monitoring can be achieved externally and internally. After performing Leopold’s maneuvers, the nurse will place the external transducer and tocodynamometer on the person’s abdomen. The external monitors provide an FHR tracing.

Applying the Ultrasound Transducer

The ultrasound transducer is placed over the fetal back closest to the fetal head, where the FHR is usually the loudest. The nurse identifies this area using Leopold’s maneuvers as previously described. The transducer is not placed over the fetal chest because movement of the extremities interferes with continuous detection of the FHR. Ultrasound gel is placed on the transducer to allow a medium for ultrasound waves to travel into and out of the uterus. The transducer is then secured by a belt.

Placement of Uterine Tocodynamometer

The toco transducer senses change in the uterine muscle during a contraction. The toco transducer is placed on the abdomen where the fundus is firmest, most often over the fetal buttocks in a cephalic presentation. While performing Leopold’s maneuvers, the nurse can assess for the optimal placement of the toco. Having determined the optimal location, the nurse secures the toco transducer to the laboring person by a belt (Figure 16.19).

Figure 16.19 Placement of External Fetal Monitors The tocodynamometer is placed on the upper uterus (fundus), and the ultrasound transducer is placed over the fetal back. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

Continuous Internal Monitoring

Internal fetal monitors consist of the fetal scalp electrode (FSE) that affixes to the scalp of the fetus and provides close monitoring of the fetal heart rate and an intrauterine pressure catheter (IUPC) that lie inside the uterus and measure the frequency, duration, and strength of the uterine contractions and the resting tone of the uterus. The amniotic sac must be ruptured prior to placement of internal monitors. Nurses and health-care providers use internal monitors in situations that require more in-depth fetal surveillance, such as nonreassuring fetal heart rates, low amniotic fluid, and difficulty in maintaining a continuous FHR tracing, and during the use of uterotonics for labor induction or augmentation.

Application of Internal Monitors

In continuous internal monitoring, an FSE is attached to the fetal scalp, avoiding the fontanelles, and the IUPC is placed into the uterus between the fetus and uterine wall. Figure 16.20 illustrates the internal fetal monitoring system.

Figure 16.20 Internal Fetal Monitor System Components of internal monitoring include the intrauterine pressure catheter used to record uterine contractions in mm Hg and the fetal scalp electrode used to record FHR. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

Internal monitors are placed by trained health-care providers and labor and birth nurses. A cervical exam is performed for assessment of dilation and membrane status. The cervix must be dilated, and the amniotic membrane must be ruptured to pass the monitors into the uterus. If the nurse assesses a need for internal monitoring, the nurse will notify the health-care provider. If the amniotic sac is intact, the health-care provider must determine the need for the monitors and weigh the pros and cons of rupturing the amniotic membrane. When appropriate, the health-care provider breaks the bag of amniotic fluid using an amniotomy hook, which is a plastic wand with a small hook that snags the membranes. Figure 16.21 illustrates use of the amniotomy hook.

Figure 16.21 Amniotomy Hook and Fetal Amniotic Sac The health-care provider uses the amniotomy hook to artificially rupture the membranes in front of the fetal head. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

Fetal Scalp Electrode

To place the fetal scalp electrode (FSE), the fetal head must be low enough to be palpated during the vaginal exam, and the cervix must be open enough to insert the FSE. The head is assessed for suture lines and fontanelles, as seen in Figure 16.22. Avoiding the fontanelles, the nurse or the health-care provider places the scalp electrode firmly against the fetal scalp and turns it clockwise to adhere the electrode. The nurse then connects the scalp electrode transducer to the monitor, and the FHR electrocardiogram is detected and documented in the monitor tracing.

Figure 16.22 Fetal Scalp Electrode Placement The fetal scalp is assessed for fontanelles and sutures. The health-care provider places the electrode on the scalp over the bone. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

Intrauterine Pressure Catheter

The IUPC, seen in Figure 16.23, is inserted using a firm plastic introducer containing the pressure catheter. The catheter has markers to guide the depth of placement to avoid uterine perforation. To avoid the IUPC being inserted through the placenta, the introducer must be retracted immediately if frank red blood is noted. The pressure catheter transducer is attached to the monitor and traces, in exact millimeters of mercury (mm Hg), the strength of the contractions and the uterine resting tone.

Figure 16.23 Intrauterine Pressure Catheter The IUPC lies between the uterus and the fetus. This internal monitor provides the strength of the contractions in mm Hg. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

Efficacy and Outcomes Data: Use of Continuous Electronic Fetal Monitoring

Continuous electronic fetal monitoring was developed in the 1970s. The original purpose of continuous electronic fetal monitoring was to decrease complications such as newborn seizures, cerebral palsy, and intrapartum fetal demise. According to the Cochrane Library (Alfirevic et al., 2017), continuous FHR monitoring with fetal scalp electrode, when compared to IA, showed no significant improvement in overall rate of fetal deaths but did significantly reduce the rate of neonatal seizures. The research found that intermittent versus continuous fetal scalp electrode monitoring did not increase instrumental or cesarean births, but no difference was seen in the incidence of cerebral palsy. Table 16.4 summarizes the advantages and disadvantages of the different fetal monitoring types.

Interpretation of the Electronic Fetal and Uterine Monitor Tracing

Interpretation of the fetal heart rate consists of evaluating the baseline, variability, and periodic changes of the FHR in relation to the uterine contractions. The nurse interprets uterine contractions by evaluating frequency, duration, strength, and resting tone. The contraction frequency is how often the contractions occur and is determined by measuring from the beginning of one contraction to the beginning of the next contraction. The contraction length is how long the contraction lasts and is determined by measuring the time between the beginning of the contraction and the end of the contraction. The contraction strength is the intensity of the contraction and is determined externally by palpation (see earlier discussion of intermittent auscultation) or internally by the IUPC. Contraction strength cannot be measured accurately when the external toco is used; therefore, the nurse palpates and describes contractions as mild, moderate, or strong. When IUPC is in use, contractions will be described in mm Hg.

Expected uterine activity is defined as five contractions or fewer in a 10-minute period. Expected contraction length is between 45 and 60 seconds and may increase to 90 seconds closer to the onset of the second stage of labor. Abnormal uterine activity called uterine tachysystole is more than five contractions in 10 minutes or a contraction length of 2 or more minutes within a 30-minute period. Uterine tachysystole can be diagnosed in both spontaneous and induced labor.

Efficiency of the uterine contractions during labor can be measured in Montevideo units. The nurse calculates the Montevideo units by subtracting the uterine resting tone in mm Hg from the mm Hg measuring the peak of the contraction for each contraction occurring within a 10-minute time interval (Kissler et al., 2020). Montevideo units can be calculated only when an IUPC is in place.

Fetal well-being is influenced by uterine activity. Therefore, when the nurse is evaluating fetal well-being, both the fetal heart rate and uterine activity, as well as the fetal response to the uterine activity, must be described. A normal fetal monitor tracing is found in Figure 16.24.

Figure 16.24 Electronic Fetal Monitor Tracing The fetal monitor traces the fetal heart rate on the top of the graph and the uterine contractions on the bottom of the graph. The middle line is the tracing of the pregnant person’s heartbeat. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

Interpretation of fetal heart rate was historically a problem because of inconsistencies in terminology and reader error. In 2008, the National Institute of Child Health and Human Development Working Group created a three-tiered classification system to interpret fetal heart rate patterns (ACOG, 2009). The three-tiered system allows for consistent terminology and management by the health-care provider and nurse. A summary of the three categories is found in Figure 16.25.

Figure 16.25 Three-Tiered System for Fetal Heart Rate Interpretation The three categories used to interpret the FHR pattern provide direction to nurses and health-care providers when determining next actions and the plan of care during the process of labor and birth. (source: ACOG, 2009; National Institute of Child Health and Human Development; attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

Category I tracings are considered normal and do not require further actions by the nurse other than routine nursing care for the antepartum or laboring patient. Figure 16.26 shows a Category I tracing. Category II tracing characteristics do not meet the criteria of either Category I or III. Nursing care requires continued surveillance with consideration of clinical circumstances and reevaluation and notification of the health-care provider. Figure 16.27 shows a Category II tracing. Category III tracings are always considered abnormal and require the nurse to contact the health-care provider with a report of the FHR abnormalities. Nursing interventions aimed at resolving the cause of the abnormality are discussed in 16.5 Intrauterine Resuscitation in this chapter. If interventions do not resolve the abnormality, the birth must be expedited, most commonly via cesarean section (ACOG, 2009). Figure 16.28 shows a Category III tracing.

Figure 16.26 Category I Fetal Heart Rate Tracing This fetal heart rate tracing shows accelerations, moderate variability, no decelerations, and uterine contractions suggesting early labor. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

Figure 16.27 Category II Tracing This fetal heart rate tracing shows minimal variability. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

Figure 16.28 Category III Tracing This fetal heart rate tracing shows absent variability with repeat variable decelerations with uterine contractions every 2 to 3 minutes. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

Documentation of the FHR and Uterine Contraction Pattern

Electronic health record (EHR) documentation during labor should include assessment of the pregnant person and the fetal heart rate. Continuous monitors record the fetal heart rate, and the tracings allow the nurse and health-care providers to review the current and previous tracing. The stored tracing also allows the nurse to care for the laboring patient during delivery and review the monitor tracing when needed.

Documentation should show evaluation of the fetal heart rate and contraction pattern every 15 to 30 minutes if there is continuous monitoring, with a summary of fetal status. The documentation should also discuss the frequency of assessment and the interpretation of the fetal heart rate. When labor-inducing medications are in use, such as oxytocin (Pitocin), the nurse should document fetal status before and after increasing the dose (Simpson, 2014).

Documentation in labor is often determined by hospital policies. Every hospital should have a policy on the frequency of fetal heart rate and contraction pattern interpretation. To ensure all components of the tracing are documented, nurses use a standardized way of describing the FHR tracing. Figure 16.29 is an example of how to organize necessary information for documentation.

Figure 16.29 Documentation of Fetal and Contraction Monitoring Nurses are expected to document specific information about the fetal heart rate and contraction patterns throughout the first and second stages of labor. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

A process for evaluating and documenting fetal monitor tracings typically includes the following steps:

1. Identify external or internal monitoring.
2. Describe FHR baseline: rate and variability.
3. Describe the presence or absence of FHR accelerations or decelerations.
4. Identify the type of deceleration if present.
5. Document the uterine contraction pattern with frequency, duration, intensity, and presence or absence of uterine resting tone.
6. Interpret the tracing and identify the tracing as Category I, II, or III.
7. Document the plan of care. Communication with the pregnant person and family is documented as part of the EHR. Nurses also document communication with the health-care provider and any new orders received from the provider.