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Does Knowing Fetal Oxygen Saturation Matter?

Use of fetal pulse oximetry made no difference in cesarean delivery rate.

Despite the wide use of intrapartum electronic fetal monitoring, its benefits have been debated, particularly in the context of cesarean delivery rates. In 2000, the FDA conditionally approved a fetal oximetry device that was developed to help characterize fetal condition in the presence of a nonreassuring heart rate. Investigators evaluated whether clinical knowledge of fetal oxygen saturation as an adjunct to conventional monitoring was associated with a reduction in the cesarean delivery rate.

They randomized more than 5000 healthy full-term nulliparous women in labor either to a "masked group" in which the fetal oxygen sensor was inserted but the oxygen saturation values were hidden from the clinicians, or to an "open group" in which the values were displayed and available to the clinicians. All women also underwent conventional electronic fetal monitoring. Rates and indications for cesarean deliveries, fetal heart tracings, and various markers of compromised neonatal condition such as Apgar <4, need for intubation, or admission to intensive care were compared.

The cesarean delivery rate did not differ significantly between the open group and the masked group (26.3% and 27.5%, respectively). In addition, the condition of the infants did not differ between the two groups. Contrary to the results of a smaller prior study, no intergroup differences in cesarean delivery rate were observed for the indication of a nonreassuring fetal heart rate or for dystocia.

Comment: Reducing the U.S. cesarean delivery rate, which is almost 30%, is certainly a laudable goal. Despite the conditional approval of a fetal pulse oximeter, acceptance of oximetry into clinical practice has awaited further clinical studies. This stands in contrast to the almost universal adaptation of conventional electronic fetal monitoring. The results of this trial do not support the idea that fetal pulse oximetry, an expensive technique, will reduce the current cesarean rate or improve neonatal outcomes.

— Ann J. Davis, MD

Published in Journal Watch Women's Health December 7, 2006

Citation(s):

Bloom SL et al. Fetal pulse oximetry and cesarean delivery. N Engl J Med 2006 Nov 23; 355:2195-202.

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