OBJECTIVE: To assess the accuracy of a pulse oximeter in the fetus. DESIGN: A prospective descriptive study, comparing oxygenation and acidaemia of cord blood with oxygen saturation in the arteries of the fetal scalp measured by a pulse oximeter just before delivery. The data were collected using an experimental pulse oximeter and a sensor specifically adapted to cope with the problems of fetal pulse oximetry. SETTING: The labour ward in a teaching hospital. SUBJECTS: Thirty seven Caucasian fetuses presenting by the vertex in normal uncomplicated labour. MAIN OUTCOME MEASURE: Fetal pulse oximetry reading shortly before birth, umbilical cord oxygenation and pH, and Apgar scores. RESULTS: Data of sufficient quality were obtained from 28 fetuses. There was a highly significant correlation between pulse oximetry reading and umbilical vein oxygen saturation r = 0.59, P = < 0.001). There was also a significant correlation between the pulse oximeter reading and cord blood pH (vein: r = 0.57, P = 0.002, artery: r = 0.63, P = 0.001). Apgar scores were not related to the oximetry results. CONCLUSION: Pulse oximetry readings reflect fetal oxygenation at birth.
OBJECTIVE: To assess the accuracy of a pulse oximeter in the fetus. DESIGN: A prospective descriptive study, comparing oxygenation and acidaemia of cord blood with oxygen saturation in the arteries of the fetal scalp measured by a pulse oximeter just before delivery. The data were collected using an experimental pulse oximeter and a sensor specifically adapted to cope with the problems of fetal pulse oximetry. SETTING: The labour ward in a teaching hospital. SUBJECTS: Thirty seven Caucasian fetuses presenting by the vertex in normal uncomplicated labour. MAIN OUTCOME MEASURE: Fetal pulse oximetry reading shortly before birth, umbilical cord oxygenation and pH, and Apgar scores. RESULTS: Data of sufficient quality were obtained from 28 fetuses. There was a highly significant correlation between pulse oximetry reading and umbilical vein oxygen saturation r = 0.59, P = < 0.001). There was also a significant correlation between the pulse oximeter reading and cord blood pH (vein: r = 0.57, P = 0.002, artery: r = 0.63, P = 0.001). Apgar scores were not related to the oximetry results. CONCLUSION: Pulse oximetry readings reflect fetal oxygenation at birth.