Strip of the Month: January 2011

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Electronic fetal monitoring (EFM) is a popular technology used to establish fetal well-being. Despite its widespread use, terminology used to describe patterns seen on the monitor has not been consistent until recently. In 1997, the National Institute of Child Health and Human Development (NICHD) Research Planning Workshop published guidelines for interpretation of fetal tracings. This publication was the culmination of 2 years of work by a panel of experts in the field of fetal monitoring and was endorsed in 2005 by both the American College of Obstetricians and Gynecologists (ACOG) and the Association of Women's Health, Obstetric and Neonatal Nurses (AWHONN). In 2008, ACOG, NICHD, and the Society for Maternal-Fetal Medicine reviewed and updated the definitions for fetal heart rate patterns, interpretation, and research recommendations. Following is a summary of the terminology definitions and assumptions found in the 2008 NICHD workshop report. Normal values for arterial umbilical cord gas values and indications of acidosis are defined in Table 1.A three-tier Fetal Heart Rate Interpretation system has been recommended as follows: Data from Macones GA, Hankins GDV, Spong CY, Hauth J, Moore T. The 2008 National Institute of Child Health and Human Development workshop report on electronic fetal monitoring. Obstet Gynecol. 2008;112:661–666.We encourage readers to examine each strip in the case presentation and make a personal interpretation of the findings before advancing to the expert interpretation provided.A 21-year-old primigravida at 32–6/7 weeks' gestation presents to labor and delivery with preterm labor. Cervical examination reveals 3 cm dilation. Her pregnancy has been complicated by maternal repaired transposition of the great vessels with ventricular inversion and first-trimester bleeding. The fetus had normal echocardiographic findings at 20 weeks' gestation. The patient has no evidence of infection, so she receives nifedipine tocolysis, betamethasone for fetal maturity, and penicillin for group B Streptococcus prophylaxis. The delivery plan is made for an assisted second stage of labor due to maternal cardiac disease. A fetal heart tracing is obtained upon admission (Fig. 1).Findings on EFT Strip #1 are: Tocolysis is discontinued after 48 hours. The woman remains stable for another 24 hours, when she begins having increased contractions and variable decelerations. On physical examination, she is 6 cm dilated, completely effaced, and −2 station. She is afebrile, and other examination findings are within normal parameters. A fetal heart tracing is obtained as her contractions begin to increase (Fig. 2).Findings on EFM Strip #2 are: The decision is made to proceed with augmentation of labor because she has completed her corticosteroid course, has advanced cervical dilation, and is having variable decelerations. Labor progresses rapidly after rupture of membranes and oxytocin augmentation, and her cervix is 9 cm dilated. An intrauterine pressure catheter (IUPC) is placed because of recurrent variable decelerations, but blood returns through the catheter, and it is removed. The fetal tracing is shown in Figure 3.Findings on EFM Strip #3 are: One hour later, the patient has a prolonged deceleration, and the decision is made to move to the operating room for further evaluation and possible operative delivery. The fetal tracing is shown in Figure 4.Findings on EFM Strip #4 are: In the operating room, the bradycardia resolves, but variable decelerations continue. Thirty minutes later, the patient is examined, and her cervix is still 9 cm dilated. A final fetal heart tracing is obtained (Fig. 5).Findings on EFM Strip #5 are: Fifteen minutes later, a primary cesarean delivery is performed. There is a single nuchal cord.A viable male infant is delivered by cesarean section. He weighs 4 lbs 4 oz and has Apgar scores of 5 at 1 minute and 7 at 5 minutes. The arterial blood gas findings are consistent with respiratory acidosis (Table 2). The baby receives continuous positive airway pressure. He is then taken to the neonatal intensive care unit, where he has a normal course for a preterm infant.This infant's FHR tracing could be explained by the presence of a nuchal cord. Single nuchal cords are seen in up to 30% of normal pregnancies. They are rarely associated with significant neonatal morbidity or mortality. Results are mixed on their association with abnormal FHR patterns, low birthweight, and umbilical artery pH of 7.10 or less. The poor sensitivity of ultrasonography in diagnosing nuchal cord and poor predictive value of adverse outcomes do not justify routine screening for its presence. (3)(4)