The efficacy of intrapartum fetal surveillance when fetal pulse oximetry is added to cardiotocography

Objective: To determine if oxygen saturation measurement with pulse oximetry (Spo(2)) in combination with cardiotocograghy (CTG), improves the assessment of the intrapartum fetal condition. Study Design: Four expert obstetricians individually evaluated 119 cases that were monitored during labor: during the first session the CTG data were available, and in the second session CTG and Spo(2) data were evaluated. They were instructed to indicate the need for intervention and to estimate the umbilical artery pH. Results: In the non-acidotic group (umbilical artery pH greater than or equal to 7.15, n = 112) the average(+/- S.D.) number of interventions decreased from 27(+/- 17) to 16(+/- 9) when Spo(2) was available. This reduction in number of interventions resulted in an significantly increased specificity for two referees. In the acidotic group (n = 7) the average number of interventions also decreased, from 6(+/- 2) to 4(+/- 2), and as a consequence the sensitivity decreased. The pH estimate based on CTG + Spo(2) was higher in both acidotic and non-acidotic fetuses than the estimated pH based on CTG alone. Conclusion: In this study all referees intervened less frequently when Spo(2) was used as an adjunct to CTG. This resulted in fewer unnecessary operative interventions, but may also lead to unidentified fetal acidosis. The number of acidotic newborns (n = 7) was too small, however, to draw definite conclusions. Larger studies should address the efficacy of Spo(2) in detecting fetal compromise before clinical use can be advocated. (C) 1997 Elsevier Science Ireland Ltd.