Sawtooth fetal heart rate pattern due to in utero fetal central nervous system injury

Abstract

Case reports We present 3 cases of documented central nervous system (CNS) injury with a characteristic fetal heart rate (FHR) sawtooth-like pattern. In the first case, there was category I fetal heart tracing during labor, which was followed by a sudden onset of fetal tachycardia, unstable and indeterminate baseline, and episodes of a sawtooth FHR pattern (Figure 1). The Apgar scores after a vaginal delivery were 9/9 at 1 and 5 minutes. The magnetic resonance imaging of the neonate, which was performed 48 hours postpartum because of facial twitches, showed infarction of the left cerebral hemisphere because of a middle cerebral artery occlusion/thrombosis; the approximate timing of the fetal stroke coincided with the abrupt onset of the aforementioned FHR changes in labor (Figure 2). In the second case, the patient was admitted with indeterminate FHR baseline and sawtooth FHR pattern (Figure 3). Emergent cesarean delivery was performed and the Apgar scores were 0/3/3 at 1, 5, and 10 minutes; the umbilical artery cord pH was 6.87, partial pressure of CO2 was 186, and base excess was e27.7. Immediately after birth the electroencephalogram was abnormal, and the infant received brain cooling but unfortunately died. In the third case, late FHR decelerations, indeterminate baseline, and periods of sawtooth FHR pattern were noted during the second stage of labor because of excessive uterine activity (Figure 4). The Apgar scores were 3/6 at 1 and 5 minutes, the cord pH was 6.90, partial pressure of CO2 was 73 and base excess was e19.5. A cranial ultrasound of the neonate revealed grade II intraventricular hemorrhage.