The utilization of transperineal ultrasound following fetal heart deceleration after epidural analgesia: a case report

BACKGROUND: We report a case of fetal heart rate decelerations and relaxation of pelvic muscles and fetal descent using transperineal ultrasound after initiation of epidural labor analgesia. CASE PRESENTATION: A 32-year-old woman, G1P0 with gestational age of 40 weeks, required epidural analgesia when her cervical dilatation was 2 cm. Baseline transperineal ultrasound examination was performed before epidural puncture. The fetal heart rate tracing was normal before the initiation of analgesia. Approximately 10 min after the epidural administration of the loading dose, the patient reported onset of analgesia and the FHR tracing showed variable-decelerations. There was no hypotension or evidence of uterine tachysystole. Transperineal ultrasound was performed again after epidural analgesia took effect. The anteroposterior diameter of the levator hiatus increased from 5.3 to 6.6 cm and angle of progress increased from 116°to 133°. The relaxation of pelvic muscle and rapid descent of fetal head may have contributed to the FHR deceleration. The midwife elevated the fetal head through the vagina with her hand, and the FHR recovered soon thereafter. CONCLUSIONS: Changes in fetal heart rate after initiation of neuraxial analgesia are unpredictable. In addition to FHR and tocodynametric monitoring, performing TPU may helpful in distinguishing the reasons for FHR change and initiating corresponding corrective measures.