Predictive value of pulse oximetry for the development of fetal acidosis

Abstract

Aims: To determine the predictive value of fetal pulse oximetry (FPO) for the development of fetal acidosis in cases of non-reassuring fetal heart rate (FHR).

Methods: In a prospective observational study, pulse oximetry monitoring was examined in cases of non-reassuring FHR during singleton cephalic delivery at 36–42 weeks' gestation. The study examined whether fetal arterial oxygen saturation (FSpO₂) values <30% for at least 10 min during the last 60 min before delivery increase the risk of fetal acidosis. The predictive reliability of this algorithm and the correlation to fetal acidosis [umbilical artery pH (UApH) <7.15] were analyzed.

Results: We included 101 patients with non-reassuring FHR during delivery. The incidence of fetal acidosis was significantly higher when FSpO₂ values <30% were recorded for at least 10 min (P=0.0). An UApH <7.15 was reliably excluded with a negative predictive value of 98.7% and detected with a sensitivity of 92.9%.

Conclusions: A low pulse oximetry oxygen saturation <30% for at least 10 min correlates highly with fetal acidosis in cases of non-reassuring FHR. FPO reliably excludes moderate to advanced acidosis and can reduce the frequency of fetal blood analysis (FBA) in cases of non-reassuring cardiotocography (CTG).