From the Editor
Transfer to the hospital for women planning a home birth: A high-risk obstetrics problem
Do you have a written clinical guideline for pregnant women planning a home birth who are transferred to your hospital?
Interpreting continuous fetal heart rate (FHR) monitoring is one of the most common tasks obstetricians perform during the course of intrapartum care. Notably, many providers do not seek ongoing training to optimize their ability to reliably and accurately interpret the FHR. Yet FHR interpretation is one of the most frequent causes of litigation in the modern obstetric practice. Failure to interpret continuous FHR monitoring appropriately is estimated to account for 75% of obstetric-related litigation.1
Continuous FHR monitoring during labor was introduced to identify infants at risk for developing hypoxic-ischemic encephalopathy (HIE). The rate of HIE has not declined, however, despite almost universal adoption of continuous FHR monitoring.2 Numerous reasons account for this failure, including ad hoc interpretation of terminology, lack of standardized protocols for management and intervention, and the oftentimes challenging patterns that must be interpreted.3 The confusion about and dissatisfaction with the current state of FHR monitoring has led to attempts to enhance our ability to identify infants at risk with additional approaches (such as fetal pulse oximetry and fetal ST-segment evaluation), and some have called for a complete overhaul of our approach to interpreting the FHR. Clark and colleagues stated recently, "It is time to start over and establish some common language, standard interpretation, and reasonable management principles and guidelines."3
We must recognize that, as a stand-alone tool, continuous FHR monitoring is ineffective for avoiding preventable adverse outcomes. It is most likely to be effective when used in accordance with published standard guidelines by professionals skilled in interpretation and when timely, appropriate interventions are performed based on that interpretation. Optimal FHR monitoring requires a collaborative perinatal team that performs the monitoring correctly, interprets it appropriately, and communicates the findings effectively, and in a timely fashion, to all members of the care team when a high-risk pattern is detected.
In this article we review some common challenges that clinicians encounter during intrapartum FHR monitoring and we offer 10 simple tips to help overcome these challenges. The clinical scenarios described are derived from published reports in the medical literature, published malpractice claims, and from our personal experience working in a major health care system as part of a team charged with overseeing ongoing certification and training of labor and delivery nurses.
Challenge: Signal ambiguity
CASE 1 Young woman in labor with first pregnancy
A 19-year-old woman presents in spontaneous labor with her first pregnancy, which has been uncomplicated. During the course of her care, it is noted that the FHR changes to a lower baseline than previously recorded. Evaluation reveals that the external monitor is tracking the maternal heart rate and not the FHR (FIGURE 1). After the monitor is adjusted, both the fetal and maternal rates are documented for a short period. Ultimately, continuous monitoring of the maternal heart rate is discontinued. After delivery of the infant several hours later, it is noted that the FHR continues to register on the monitor, and it is determined that for the last few hours the maternal heart rate has been traced.
| FIGURE 1 FHR tracing indicates signal ambiguity | ||
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As described in Case 1, the upper panel of this tracing demonstrates the maternal heart rate confused as the fetal heart rate, while the segment in the lower panel shows a clear distinction between the maternal and fetal heart rates. | ||
TIP #10: Ensure the FHR monitor is tracking the fetal, not the maternal, heart rate
Confusing the maternal and the fetal heart rate with external cardiotocography is common. When the mix-up is noted and corrected expeditiously, it is unlikely to result in an adverse outcome. Signal ambiguity may arise from faulty Doppler equipment or the inability of the cardiotocograph to differentiate between maternal and fetal heart rates. It commonly occurs after repositioning the patient, after fetal movement, or during pushing in the second stage when the maternal heart rate may increase to a baseline that is similar to that of the fetus.
Signal ambiguity should be suspected when the FHR runs in the low-normal range or when FHR accelerations are noted with greater than 50% of contractions (especially when pushing).4 Signal ambiguity also should be ruled out when there is an apparent FHR deceleration to the maternal range that does not recover.
Evaluating for suspected signal ambiguity involves 2 key steps: (1) documentation and verification of the maternal heart rate and (2) definitive documentation of the true FHR. To document the maternal heart rate, manually count the radial pulse for 1 minute or use a pulse oximeter for continuous monitoring. Using a pulse oximeter is a less labor-intensive approach and has the advantage of allowing continuous assessment of the maternal heart rate for comparison. Recording the maternal pulse continuously on the same screen as the FHR enables ongoing differentiation of the mother and fetus in difficult cases, particularly if internal fetal monitoring is not an option (because of maternal infectious disease, low suspicion for an abnormal FHR pattern, or strong maternal preference against internal monitoring, for example).
