[Continuous monitoring of fetal oxygen saturation (FSpO2) using intrapartum fetal pulse oximetry (IFPO) in the diagnosis of acute fetal hypoxia].

OBJECTIVE

The aim of the study was to evaluate the possibility of lowering the Caesarean Section rate in patients presenting the signs of intrauterine hypoxia on CTG tracing by evaluating the foetal oxygen saturation (FSpO2) by means of intrapartum foetal pulse oximetry (IFPO).

METHODS

Open prospective study.

METHODS

1st Department of Gynecology and Obstetrics, Medical Faculty of Masaryk University, Brno.

METHODS

From January 1, 1999 to December, 1999 68 patients were enrolled in the study. For the application of the IFPO sensor the patient had to meet the following criteria: patient's informed consensus, pregnancy > or = 36 weeks, regular uterine contractions, rupture of membranes, cervical dilatation of > or = 2 cm, singleton pregnancy, cephalic occiput presentation, no sings of vaginal infection, acute foetal hypoxia on CTG tracing: (baseline heart rate < 100 beats/min of different patterns. Progressive bradycardia: baseline heart rate gradually decreases between contractions (DIP II, DIP 0). Persisting bradycardia, baseline < 80 beats/min. Baseline tachycardia (> 150 beats/min) with reduced variability and/or severe variable (DIP 0) and late decelerations (DIP II). The IFPO used--Nellcor N-400. In all patients that fulfilled the above mentioned criteria during the first stage of labor the sensor was applied preferably on the posterior cheek of the foetus and the FSpO2 values were continuously monitored up to the complete dilatation. The threshold of the intrapartum foetal hypoxia (FSpO2 values) was considered < 30% for more than 10 minutes. In cases of normal FSpO2 values the delivery was conducted vaginally even if the CTG tracing continued to signalise++ intrauterine hypoxia. In case of pathologic FSpO2 values, Caesarean Section was performed.

RESULTS

IFPO is an easy feasible method and in all cases the values of FSpO2 were obtained. The method has no serious side effects neither in the mother nor in the foetus. Nevertheless the presence of the sensor in the uterine cavity provokes often unpleasant feelings and limits the mother in free movements. In all suspicious CTG tracings (17) no Caesarean Sections were performed after the verification of the foetal hypoxia by means of FSpO2 evaluation. In 51 patients a pathologic CTG tracing indicating the performance of Caesarean Section was present. After FSpO2 evaluation the Caesarean Section was performed only in 11 (21.6%) patients. The remaining 40 (78.4%) delivered vaginally. Between these two groups there was statistical difference in the values of FSpO2 and postpartum cord pH. The state of newborns evaluated according to the Apgar score did not significantly differ in the two groups.

CONCLUSIONS

These preliminary results indicate that taking in an account foetal SpO2 evaluated by IFPO in the 1st stage of labor in cases of pathologic CTG tracing (late and variable deceleration) indicating Caesarean Section, > 50% of these may be saved with identical perinatal outcome (Apgar scores, cord pH).