Analysis of Present Diagnostic Methods of Intrapartal Fetal Hypoxia

Overview

Objective:
To evaluate specificity of present diagnostic methods of intrapartal fetal hypoxia (cardiotocography – CTG, fetal pulse oxymetry – FpO₂, ST-ECG analysis).

Design:
A prospective study.

Setting:
Gynecology-Obstetrics Clinic, 1st Medical Faculty and General Faculty Hospital in Prague.

Methods:
The results of synchronic fetus monitoring by means of CTG, FpO₂ and STAN-ST 21 were followed in 53 mothers with a risk and pathological delivering of birth in the period of April 2003 to March 2004. The study investigated, which of the methods provided the best prediction of the intrapartal fetal hypoxia. The statistical evaluation (p-mark test and Mc Namara test) was based on the assessment of correct or incorrect prediction of the Apgar score values in the first minute after birth, pH in umbilical artery and the lactate level. We also investigated results of three methods during postpartum depression, turbid or mushy amniotic fluid and the way the individual methods were made useful in indication for ending the delivery.

Results:
In comparison with CTG there was a statistically significantly higher specificity in FpO₂ and STAN in the evaluation of Apgar score in the newborn in the first minute after birth, FpO₂ (p=0.007) and STAN-ST (p<0.001), in the determination of pH (a) from umbilical blood FpO₂ (p=0.029) and STAN (p=0.001) and the occurrence of postpartum depression of the newborn in minute 30–60 after birth FpO₂ (p=0.019) and STAN (p=0.0005). The changes in lactate level in umbilical blood were better predicated by STAN (p=0.001). FpO₂ evaluated the changes in the same way as CTG. The threatening hypoxia in strongly turbid or even mushy amniotic fluid was correctly evaluated by STAN only (p=0.002). The FpO₂ evaluation was not statistically significant. There was no any statistically significant difference in the indication of operation for ending the delivery among the individual methods.

Conclusions:
The results univocally demonstrated that the used of other method for diagnosis on intrapartal fetus hypoxia – Fetal pulse oxymetry and ST – analysis of ECG of the fetus give more precision to the diagnosis. The introduction of these methods requires a correct interpretation and the effort of the obstetrician to use these methods in clinical practice.

Key words:
cardiotocography, fetal pulse oxymetry, ST-analysis of fetus ECG, diagnostics for intrapartal fetus hypoxia