Dual System Study: Transvaginal Fetal Pulse Oximetry Measurement Systems

The Raydiant Data Collection System (DCS) captures red and infrared waveforms that can be post-processed to calculate fetal functional oxygen saturation of arterial oxygen saturation (SpO2) and pulse rate. These waveforms are acquired from the fetus when the sensor is placed at the cheek, temple, or forehead. Acquisition of these waveforms is a necessary step toward signal qualification and data processing algorithms. The Raydiant DCS is a similar device to the original Nellcor N-400 System. Clinical research with the N-400 System demonstrated that fetal pulse oximetry values provide 54.2% positive predicative value and 92.9% sensitivity for detecting newborn metabolic acidosis (defined by pH<7.15).1 This provided a significant aid to clinicians for diagnosing endangering states of fetal hypoxia.

In this study, both the participants and the health-care providers are blinded to the oximetry data; therefore, clinical decisions regarding interventions are made based on routine clinical monitoring. The primary analysis will be performed by comparing the post-processed waveforms. Other than device placement and a period of monitoring not to exceed 6 hours, there is no change to the standard of care procedures for fetal monitoring. As stated above, the sensor displays will not be used to guide or alter patient management.

Inclusion criteria

• Willing and capable of providing informed consent.
• Age > 18 years.
• Gestational age > 36 weeks.
• Singleton pregnancy.
• Vertex presentation,
• In latent or active labor,
• Category I or II tracings,
• Epidural anesthesia, and
• Ruptured amniotic sac with cervical dilation of >2 cm and a station of -2 or lower.

Exclusion criteria

• Age < 18 years.
• Gestational age < 36 weeks
• Multiple gestation
• Nonvertex fetal presentation
• Suspected vasa previa
• Category III CTG tracing
• Fetal anomalies and/or chromosomal disorders
• Chorioamnionitis
• Placenta previa
• HIV, genital Herpes, or other infection precluding transvaginal monitoring
• Unable to provide informed consent (e.g., cognitively impaired)
• Low anterior placenta, or
• Any condition (temporary or permanent) in which the investigator deems the patient unsuitable for the study procedures.