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

Objective : To determine if oxygen saturation measurement with pulse oximetry (Sp o 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 Sp o 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≥7.15, n =112) the average(±S.D.) number of interventions decreased from 27(±17) to 16(±9) when Sp o 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+Sp o 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 Sp o 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 Sp o 2 in detecting fetal compromise before clinical use can be advocated. © 1997 Elsevier Science Ireland Ltd.