Transabdominal measurement of oxygenation of the placenta by near-infrared spectroscopy.

Near-infrared spectroscopy (NIRS) has been used as a noninvasive method for monitoring the real-time oxygenation status in areas such as the brain and striated muscle. Because the oxygenation status of the placenta is closely related to the fetal condition, monitoring placental oxygenation through the maternal abdomen is desirable. We performed transabdominal monitoring of oxygenation of the placenta by NIRS in 11 women. We improved the conventional probe of the NIRO 300 system (Hamamatsu Photonics KK, Hamamatsu, Japan) to obtain placental oxygenation data. With this probe, we succeeded in obtaining oxyhemoglobin and deoxyhemoglobin data through the maternal abdomen. We believe NIRS will prove to be useful for intrapartum monitoring.