Variable and inconsistent interpretation of tracings by clinicians may affect management of patients. The effect of continuous EFM monitoring on malpractice liability has not been well established. Other rare risks associated with EFM include fetal scalp infection and uterine perforation with the intra-uterine tocometer or catheter. Some clinicians have argued that this unproven technology has become the standard for all patients designated high risk and has been widely applied to low-risk patients as well.
A systematic approach is recommended when reading FHR recordings to avoid misinterpretation Table 2. The FHR recordings may be interpreted as reassuring, nonreassuring or ominous, according to the pattern of the tracing. Reassuring patterns correlate well with a good fetal outcome, while nonreassuring patterns do not. Evaluation of fetal well-being using fetal scalp stimulation, pH measurement, or both, is recommended for use in patients with nonreassuring patterns.
Table 3 lists examples of nonreassuring and ominous patterns. The FHR tracing should be interpreted only in the context of the clinical scenario, and any therapeutic intervention should consider the maternal condition as well as that of the fetus.
For example, fetuses with intrauterine growth restriction are unusually susceptible to the effect of hypoxemia, which tends to progress rapidly. Identify type of monitor used—external versus internal, first-generation versus second-generation. Identify baseline fetal heart rate and presence of variability, both long-term and beat-to-beat short-term. Identify pattern of uterine contractions, including regularity, rate, intensity, duration and baseline tone between contractions.
Correlate accelerations and decelerations with uterine contractions and identify the pattern. Develop a plan, in the context of the clinical scenario, according to interpretation of the FHR. Document in detail interpretation of FHR, clinical conclusion and plan of management. Nonreassuring variable decelerations associated with loss of beat-to-beat variability.
Confirmed loss of beat-to-beat variability not associated with fetal quiescence, medications or severe prematurity. A growing body of evidence suggests that, when properly interpreted, FHR assessment may be equal or superior to measurement of fetal blood pH in the prediction of both good and bad fetal outcomes. Fetal scalp sampling for pH is recommended if there is no acceleration with scalp stimulation.
A scalp pH less than 7. Results in this range must also be interpreted in light of the FHR pattern and the progress of labor, and generally should be repeated after 15 to 30 minutes. A scalp pH of less than 7. Table 4 lists recommended emergency interventions for nonreassuring patterns.
Determine whether operative intervention is warranted and, if so, how urgently it is needed. Adapted with permission from Wolkomir MS. Understanding and interpreting intrapartum fetal heart rate monitoring.
The FHR is controlled by the autonomic nervous system. The inhibitory influence on the heart rate is conveyed by the vagus nerve, whereas excitatory influence is conveyed by the sympathetic nervous system.
Progressive vagal dominance occurs as the fetus approaches term and, after birth, results in a gradual decrease in the baseline FHR. Stimulation of the peripheral nerves of the fetus by its own activity such as movement or by uterine contractions causes acceleration of the FHR. Baroreceptors influence the FHR through the vagus nerve in response to change in fetal blood pressure.
Almost any stressful situation in the fetus evokes the baroreceptor reflex, which elicits selective peripheral vasoconstriction and hypertension with a resultant bradycardia. Hypoxia, uterine contractions, fetal head compression and perhaps fetal grunting or defecation result in a similar response. Chemoreceptors located in the aortic and carotid bodies respond to hypoxia, excess carbon dioxide and acidosis, producing tachycardia and hypertension.
The normal FHR range is between and beats per minute bpm. The baseline rate is interpreted as changed if the alteration persists for more than 15 minutes. Prematurity, maternal anxiety and maternal fever may increase the baseline rate, while fetal maturity decreases the baseline rate. The FHR is under constant variation from the baseline Figure 1. This variability reflects a healthy nervous system, chemoreceptors, baroreceptors and cardiac responsiveness.
Prematurity decreases variability 16 ; therefore, there is little rate fluctuation before 28 weeks. Variability should be normal after 32 weeks. Beat-to-beat or short-term variability is the oscillation of the FHR around the baseline in amplitude of 5 to 10 bpm. Long-term variability is a somewhat slower oscillation in heart rate and has a frequency of three to 10 cycles per minute and an amplitude of 10 to 25 bpm.
Clinically, loss of beat-to-beat variability is more significant than loss of long-term variability and may be ominous. Reassuring pattern. Baseline fetal heart rate is to beats per minute bpm , preserved beat-to-beat and long-term variability.
Accelerations last for 15 or more seconds above baseline and peak at 15 or more bpm. Interpretation of the FHR variability from an external tracing appears to be more reliable when a second-generation fetal monitor is used than when a first-generation monitor is used.
Beta-adrenergic agonists used to inhibit labor, such as ritodrine Yutopar and terbutaline Bricanyl , may cause a decrease in variability only if given at dosage levels sufficient to raise the fetal heart rate above bpm.
Increased variability in the baseline FHR is present when the oscillations exceed 25 bpm Figure 2. This pattern is sometimes called a saltatory pattern and is usually caused by acute hypoxia or mechanical compression of the umbilical cord.
This pattern is most often seen during the second stage of labor. The presence of a saltatory pattern, especially when paired with decelerations, should warn the physician to look for and try to correct possible causes of acute hypoxia and to be alert for signs that the hypoxia is progressing to acidosis.
Saltatory pattern with wide variability. The oscillations of the fetal heart rate above and below the baseline exceed 25 bpm. Fetal tachycardia is defined as a baseline heart rate greater than bpm and is considered a nonreassuring pattern Figure 3. Tachycardia is considered mild when the heart rate is to bpm and severe when greater than bpm. Tachycardia greater than bpm is usually due to fetal tachyarrhythmia Figure 4 or congenital anomalies rather than hypoxia alone.
Fetal tachycardia with possible onset of decreased variability right during the second stage of labor. Fetal heart rate is to bpm. Mild variable decelerations are present.
Fetal tachycardia that is due to fetal tachyarrhythmia associated with congenital anomalies, in this case, ventricular septal defect. Fetal heart rate is bpm. Hydroxyzine Atarax. Ritodrine Yutopar. Terbutaline Bricanyl. Persistent tachycardia greater than bpm, especially when it occurs in conjunction with maternal fever, suggests chorioamnionitis. Fetal tachycardia may be a sign of increased fetal stress when it persists for 10 minutes or longer, but it is usually not associated with severe fetal distress unless decreased variability or another abnormality is present.
Fetal bradycardia is defined as a baseline heart rate less than bpm. Bradycardia in the range of to bpm with normal variability is not associated with fetal acidosis.
Bradycardia of this degree is common in post-date gestations and in fetuses with occiput posterior or transverse presentations. Severe prolonged bradycardia of less than 80 bpm that lasts for three minutes or longer is an ominous finding indicating severe hypoxia and is often a terminal event.
If the cause cannot be identified and corrected, immediate delivery is recommended. Accelerations are transient increases in the FHR Figure 1. They are usually associated with fetal movement, vaginal examinations, uterine contractions, umbilical vein compression, fetal scalp stimulation or even external acoustic stimulation.
The presence of at least two accelerations, each lasting for 15 or more seconds above baseline and peaking at 15 or more bpm, in a minute period is considered a reactive NST. Early decelerations are caused by fetal head compression during uterine contraction, resulting in vagal stimulation and slowing of the heart rate.
This type of deceleration has a uniform shape, with a slow onset that coincides with the start of the contraction and a slow return to the baseline that coincides with the end of the contraction. Thus, it has the characteristic mirror image of the contraction Figure 5.
Although these decelerations are not associated with fetal distress and thus are reassuring, they must be carefully differentiated from the other, nonreassuring decelerations. Early deceleration in a patient with an unremarkable course of labor.
Notice that the onset and the return of the deceleration coincide with the start and the end of the contraction, giving the characteristic mirror image. Late decelerations are associated with uteroplacental insufficiency and are provoked by uterine contractions. Any decrease in uterine blood flow or placental dysfunction can cause late decelerations.
Maternal hypotension and uterine hyperstimulation may decrease uterine blood flow. Postdate gestation, preeclampsia, chronic hypertension and diabetes mellitus are among the causes of placental dysfunction.
Other maternal conditions such as acidosis and hypovolemia associated with diabetic ketoacidosis may lead to a decrease in uterine blood flow, late decelerations and decreased baseline variability. A late deceleration is a symmetric fall in the fetal heart rate, beginning at or after the peak of the uterine contraction and returning to baseline only after the contraction has ended Figure 6. The descent and return are gradual and smooth. Studies have shown cortical and midbrain damage due to uteroplacental insuffiency.
When late decelerations appear, prompt intervention is required. Nursing interventions, when the nurse recognizes them, is highly individualized, and how long she allows them to persist is also highly individualized. Recurrent late decelerations and recurrent variable decelerations, and fetal bradycardia, as well as low fetal scalp pH are indications for prompt action, such as an emergency cesarean section, if an instrumental delivery with its own antecedent risks cannot be performed immediately.
When a fetal scalp monitor readings are low especially below 7. Sadly, this is rarely the case. We are available any time to discuss your potential case. Call us at , chat with us online, or email info passenpowell. There is absolutely no fee for a consultation with one of our attorneys. You can also contact us by filling out the form below. Tel: Connect With Us. About Testimonials Attorneys Matthew A. Passen Jordan S. Powell Stephen M.
Late Decelerations Time is critical when your fetal heart tracing shows late decelerations. Please do not include any confidential or sensitive information in a contact form, text message, or voicemail. The contact form sends information by non-encrypted email, which is not secure. Submitting a contact form, sending a text message, making a phone call, or leaving a voicemail does not create an attorney-client relationship. Practice Areas. Birth Injuries.
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