A nurse is caring for a full-term client in labor who is prescribed continuous fetal monitoring. On examination, the nurse determines the client's membranes are intact. Which of the following assessment methods should the nurse implement?

Choice A rationale A transvaginal fetal Doppler probe is an internal device used early in pregnancy to confirm fetal viability or heart rate in the first trimester, not an appropriate method for continuous intrapartum monitoring in a full-term client with intact membranes. Choice B rationale The DeLee-Hillis fetoscope is an external acoustic device used for intermittent auscultation of the fetal heart rate, providing a listening assessment rather than the prescribed continuous electronic tracing required for this client. Choice C rationale An external ultrasound transducer monitor (or tocodynamometer for contractions) uses non-invasive Doppler technology placed on the client's abdomen to detect and continuously monitor the fetal heart rate and uterine contractions when membranes are intact, satisfying the continuous monitoring prescription without internal access. Choice D rationale An internal fetal scalp electrode (FSE) requires the rupture of membranes and sufficient cervical dilation for placement onto the fetal scalp to provide a precise electrocardiogram of the fetal heart, which is not applicable since the client's membranes are intact.