Validation of arterial oxygen saturation measurements in utero using pulse oximetry.

The noninvasive measurement of fetal arterial oxygen saturation using pulse oximetry could be of potential use in assessing fetal well-being in utero during labor. In this study, the accuracy and technical feasibility of reflectance pulse oximetry in utero was evaluated in acutely instrumented fetal sheep using a specially designed sensor. Following recalibration of the analysis algorithms, fetal arterial saturation could be measured by pulse oximetry in utero. Arterial oxygenation measurements obtained using pulse oximetry correlated well with simultaneous in vitro measurements over the range of 6 to 81%. We conclude that in utero pulse oximetry is technically feasible, appears useful and accurate, and merits further evaluation.