Because labor is a period of physiologic stress for the fetus, frequent monitoring of fetal status is part of the nursing care during labor. The goals of intrapartum FHR monitoring are to identify and differentiate the normal (reassuring) patterns from the abnormal (nonreassuring) patterns, which can be indicative of fetal compromise. Fetal well-being during labor can be assessed by the response of the FHR to uterine contractions.

Monitoring Techniques

Intermittent Auscultation (IA)

Uses listening to fetal heart sounds at periodic intervals to assess the FHR

IA can be performed with a Pinard stethoscope, a Doppler ultrasound device, an ultrasound stethoscope, or a DeLee-Hillis fetoscope.

Advantages: easy to use, inexpensive, and less invasive than electronic fetal monitoring. It is often more comfortable for the woman and gives her more freedom of movement.

Disadvantages: may be difficult to perform in women who are obese. Because IA is intermittent, significant events may occur during a time when the FHR is not being auscultated. Also IA does not provide a permanent documented visual record of the FHR.

Box 3-4 describes how to perform IA.

BOX 3-4

Procedure for Intermittent Auscultation of the Fetal Heart Rate

1. Palpate the maternal abdomen to identify fetal presentation and position.

2. Apply ultrasonic gel to the device if using a Doppler ultrasound. Place the listening device over the area of maximal intensity and clarity of the fetal heart sounds to obtain the clearest and loudest sound, which is easiest to count. This location will usually be over the fetal back. If using the fetoscope, firm pressure may be needed.

3. Count the maternal radial pulse while listening to the fetal heart rate (FHR) to differentiate it from the fetal rate.

4. Palpate the abdomen for the presence or absence of uterine activity (UA) so as to count the FHR between contractions.

5. Count the FHR for 30 to 60 sec between contractions to identify the auscultated rate, best assessed in the absence of UA.

6. Auscultate the FHR before, during, and after a contraction to identify the FHR during the contraction, as a response to the contraction, and to assess for the absence or presence of increases or decreases in FHR.

7. When distinct discrepancies in the FHR are noted during listening periods, auscultate for a longer period during, after, and between contractions to identify significant changes that may indicate the need for another mode of FHR monitoring.

Source: Tucker, S., Miller, L., & Miller, D. (2009). Mosby’s pocket guide to fetal monitoring: A multidisciplinary approach (6th ed.). St. Louis: Mosby.

NURSING ALERT

When the FHR is auscultated and documented, it is inappropriate to use the descriptive terms associated with electronic fetal monitoring (e.g., moderate variability, variable deceleration) because most of the terms are visual descriptions of the patterns produced on the monitor tracing. Terms that are numerically defined, however, such as bradycardia and tachycardia, can be used. Fetal heart rate when auscultated should be described as a baseline number or range, and as having a regular or irregular rhythm. The presence or absence of accelerations or decelerations both during and after contractions should also be noted.

Uterine Activity (UA) Assessment

UA is assessed by palpation. The examiner should keep his or her fingertips placed over the fundus before, during, and after contractions.

Contraction intensity is usually described as mild, moderate, or strong.

Contraction frequency is measured in minutes, from the beginning of one contraction to the beginning of the next contraction.

Contraction duration is measured in seconds, from the beginning to the end of the contraction.

To evaluate uterine resting tone, or relaxation between contractions, the examiner should keep his or her hand on the fundus after the contraction is over. Resting tone between contractions is usually described as soft or relaxed.

Electronic Fetal Monitoring (EFM)

There are two modes of electronic FHR and contraction monitoring: external and internal. See Table 3-1 for differences in these monitoring modes.

TABLE 3-1

External and Internal Modes of Monitoring

EXTERNAL MODE	INTERNAL MODE
FETAL HEART RATE
Ultrasound transducer: High-frequency sound waves reflect mechanical action of the fetal heart. Noninvasive. Does not require rupture of membranes or cervical dilation. Used during both the antepartum and intrapartum periods.	Spiral electrode: Converts the fetal ECG as obtained from the presenting part to the FHR via a cardiotachometer. Can be used only when membranes are ruptured and the cervix is sufficiently dilated during the intrapartum period. Electrode penetrates into fetal presenting part by 1.5 mm and must be attached securely to ensure a good signal.
UTERINE ACTIVITY
Tocotransducer: Monitors frequency and duration of contractions by means of a pressure-sensing device applied to the maternal abdomen. Used during both the antepartum and intrapartum periods.	Intrauterine pressure catheter (IUPC): Monitors the frequency, duration, and intensity of contractions. The two types of IUPCs are a fluid-filled system and a solid catheter. Both measure intrauterine pressure at the catheter tip and convert the pressure into millimeters of mercury on the uterine activity panel of the strip chart. Both can be used only when membranes are ruptured and the cervix is sufficiently dilated during the intrapartum period.

ECG, Electrocardiogram; FHR, fetal heart rate.

Standardized Definitions for FHR Monitoring

Baseline Patterns

Baseline FHR: average FHR during a 10-minute period that excludes periodic and episodic changes and periods of marked variability; the normal range at term is 110 to 160 beats/min. Baseline FHR is recorded as a single number, not a range.

Bradycardia: baseline FHR less than 110 beats/min and lasting for 10 minutes or longer

Tachycardia: baseline FHR more than 160 beats/min and lasting for 10 minutes or longer

Causes, clinical significance, and nursing interventions for tachycardia and bradycardia are listed in Table 3-2.

TABLE 3-2

Tachycardia and Bradycardia

TACHYCARDIA	BRADYCARDIA
DEFINITION
FHR >160 beats/min lasting >10 min	FHR <110 beats/min lasting >10 min
POSSIBLE CAUSES
Early fetal hypoxemia	Atrioventricular dissociation (heart block)
Fetal cardiac arrhythmias	Structural defects
Maternal fever	Viral infections (e.g., cytomegalovirus)
Infection (including chorioamnionitis)	Medications
Parasympatholytic drugs (atropine, hydroxyzine)	Fetal heart failure
β-Sympathomimetic drugs (terbutaline)	Maternal hypoglycemia
Maternal hyperthyroidism	Maternal hypothermia
Fetal anemia
Drugs (caffeine, cocaine, methamphetamines)
CLINICAL SIGNIFICANCE
Persistent tachycardia in the absence of periodic changes does not appear serious in terms of neonatal outcome (especially true if tachycardia is associated with maternal fever); tachycardia is abnormal when associated with late decelerations, severe variable decelerations, or absent variability.	Baseline bradycardia alone is not specifically related to fetal oxygenation. The clinical significance of bradycardia depends on the underlying cause and the accompanying FHR patterns, including variability, accelerations, or decelerations.
NURSING INTERVENTIONS
Dependent on cause; reduce maternal fever with antipyretics as ordered and cooling measures; oxygen at 8 or 10 L/min by nonrebreather face mask may be of some value; carry out health care provider’s orders based on alleviating cause.	Dependent on cause

FHR, fetal heart rate.

FHR variability: normal irregularity of fetal cardiac rhythm or fluctuations from the baseline FHR of two cycles or more; the four possible categories of variability are absent, minimal, moderate, and marked. Figure 3-4 shows the four possible categories of variability.

Fig. 3-4 Fetal heart rate variability. A, Absent variability; amplitude range undetectable. B, Minimal variability; amplitude range detectable up to and including 5 beats/min. C, Moderate variability; amplitude range 6 to 25 beats/min. D, Marked variability; amplitude range more than 25 beats/min. (From Tucker, S., Miller, L., & Miller, D. [2009]. *Mosby’s pocket guide to fetal monitoring: A multidisciplinary approach* [6th ed.]. St. Louis: Mosby.

Periodic and Episodic Patterns

Acceleration: a visually apparent, abrupt (onset to peak <30 seconds) increase in FHR above the baseline rate; the increase is 15 beats/min or greater and lasts 15 seconds or more, with the return to baseline less than 2 minutes from the beginning of the acceleration; an acceleration lasting more than 10 minutes is considered a baseline change

Figure 3-5 shows an example of accelerations. Box 3-5 lists causes, clinical significance, and nursing interventions for accelerations.

Deceleration: there are four types of FHR decelerations that may occur in labor: early, late, variable, and prolonged; FHR decelerations are defined according to their visual relation to the onset and end of a contraction and by their shape.

Early deceleration: a visually apparent gradual (onset to lowest point 30 seconds or more) decrease in and return to the baseline FHR associated with uterine contractions (UCs); generally the onset, nadir, and recovery of the deceleration correspond to the beginning, peak, and end of the contraction.

BOX 3-5

Accelerations

Causes

Spontaneous fetal movement

Vaginal examination

Electrode application

Fetal scalp stimulation

Fetal reaction to external sounds

Breech presentation

Occiput posterior position

Uterine contractions

Fundal pressure

Abdominal palpation

Clinical Significance

Normal pattern. Acceleration with fetal movement signifies fetal well-being representing fetal alertness or arousal states.

Nursing Interventions

None required

Figure 3-6 shows an example of early decelerations. Box 3-6 lists causes, clinical significance, and nursing interventions for early decelerations.

Late deceleration: a visually apparent gradual (onset to lowest point 30 seconds or more) decrease in and return to baseline FHR associated with UCs; the deceleration begins after the contraction has started, and the lowest point of the deceleration occurs after the peak of the contraction; the deceleration usually does not return to baseline until after the contraction is over.

BOX 3-6

Early Decelerations

Cause

Head compression resulting from the following:

Uterine contractions

Vaginal examination

Fundal pressure

Placement of internal mode of monitoring

Clinical Significance

Normal pattern. Not associated with fetal hypoxemia, acidemia, or low Apgar scores

Nursing Interventions

None required

Figure 3-7 shows an example of late decelerations. Box 3-7 lists causes, clinical significance, and nursing interventions for late decelerations.

Variable deceleration: a visually abrupt (onset to lowest point <30 seconds) decrease in FHR below the baseline; the decrease is 15 beats/min or more, lasts at least 15 seconds, and returns to baseline in less than 2 minutes from the time of onset; variable decelerations are not necessarily associated with UCs; they have a U, V, or W shape

BOX 3-7

Late Decelerations

Cause

Uteroplacental insufficiency caused by the following:

Uterine tachysystole

Maternal supine hypotension

Epidural or spinal anesthesia

Placenta previa

Placental abruption

Hypertensive disorders

Postmaturity

Intrauterine growth restriction

Diabetes mellitus

Intraamniotic infection

Clinical Significance

Abnormal pattern associated with fetal hypoxemia, acidemia, and low Apgar scores; considered ominous if persistent and uncorrected, especially when associated with fetal tachycardia and loss of variability