Tachysystole and Late Decelerations After Misoprostol
30-year-old G1 at 41 weeks 1 day is admitted for induction with a Bishop score of 3. She received misoprostol 25 µg vaginally 4 hours ago, and a second dose was placed 2 hours ago. Contractions now occur every 2 minutes and last 70 seconds. The fetal heart rate is 150 beats/min with minimal variability and recurrent late decelerations. Maternal BP is 118/70 mmHg, pulse 98 beats/min, temperature 37.8°C, and cervical examination is 4 cm dilated, 80% effaced, station −1. Membranes are intact. Oxytocin has not been started, and an epidural is in place. There is no vaginal bleeding. The unit has terbutaline and immediate cesarean capability.
1. Interpret the fetal heart tracing and contraction pattern, and list immediate intrauterine resuscitation steps.
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This is a category II tracing with minimal variability and recurrent late decelerations in the setting of tachysystole, defined as more than five contractions in 10 minutes averaged over 30 minutes. Late decelerations suggest uteroplacental insufficiency, and misoprostol is the likely cause. Stop misoprostol immediately, reposition the patient to the left lateral position, give an IV crystalloid bolus, and consider terbutaline 250 µg subcutaneously if tachysystole persists. Oxygen is not routinely recommended without maternal hypoxemia. Notify anesthesia and neonatology, maintain continuous monitoring, and check for cord prolapse if membranes rupture. Do not start oxytocin. Document the times of each intervention and the response.
2. After two tocolytic doses and 20 minutes, the late decelerations persist and the cervix remains 4 cm. What is the next step and why?
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Proceed with cesarean delivery for nonreassuring fetal status. Persistent late decelerations after intrauterine resuscitation indicate ongoing fetal hypoxia, and at 4 cm dilation a vaginal delivery is not imminent. Continuing induction would prolong fetal exposure and increase the risk of acidemia. Alert the operating room, anesthesia, and neonatal team, and prepare for cesarean with left uterine displacement and maternal blood pressure support. Do not give further misoprostol or oxytocin. The indication, timing of interventions, and tracing interpretation should be documented clearly.
3. If the tracing normalizes and contractions stop, how would you counsel about continuing induction?
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If the tracing becomes category I and tachysystole resolves, wait at least 4 hours after the last misoprostol dose before considering oxytocin. Use the lowest effective oxytocin dose with continuous monitoring and reassess the Bishop score. Counsel that she has already had uterine hyperstimulation and that recurrence is possible, so the threshold for cesarean should be low. If tachysystole or late decelerations recur, stop oxytocin and proceed to delivery. Mechanical ripening or cesarean delivery are alternatives. Document a shared decision that weighs the benefits of vaginal delivery against the risk of recurrent fetal intolerance.