Intrapartal Fetal Monitoring, Sensitivity and Specificity of Methods
Hájek Z.1, Srp B.1, Pavlíková M.2, Zvárová J.2, Liška K.1, El Haddad R.1, Pašková A.1, Pařízek A.1
1Gynekologicko-porodnická klinika 1. LF UK a VFN, Praha, přednosta prof. MUDr. A. Martan, DrSc. 2EuroMise centrum, Ústav informatiky AV ČR, Praha, ředitelka prof. RNDr. J. Zvárová, DrSc. |
|
Summary:
Objective: To evaluated sensitivity and specificity of presently used methods for intrapartal monitoring
(CTG, FpO2 a STAN S-21) and their mutual comparison.
Type of study: A prospective study.
Setting: Gynecological–Obstetrical Clinic, 1st Medical Faculty, Charles University and general Teaching
Hospital, Prague.
Method: In 114 pregnant women with high-risk or pathological course of pregnancy the authors evaluated
the capability of individual methods to predict intrapartal hypoxia, determined on the basis of postnatal
evaluation of parameters observed (Apgar score in 1st minute, pH from umbilical artery, lactate
levels in fetal blood, base excess (BE) and postpartum condition of fetus evaluated by a neonatologist).
Each method was categorized according to its importance. The quality of individual methods was evaluated
by means of their sensitivity and specificity as well as by the area under ROC (Receiver Operating
Characteristic), i.e. AUC (Area under Curve). A similar or different prediction of the condition of the
newborn by these individual methods was evaluated by the McNamara test of symmetry. In 50 deliveries
performed by Cesarean section and 24 forceps deliveries the authors evaluated postnatal pH from
umbilical artery and evaluation by Chi-square test. The women in childbed were infused with a tocolytic
drug (hexoprenalin) before Cesarean section. All tests were performed at 5% level of significance.
Results: Low level of Apgar score in the 1st minute and less) always indicated CTG, but also a large proportion
of normal newborns. STAN, in contrast, well indicates all newborns with a normal point evaluation.
The best balanced evaluation of the newborns is provided by FpO2 and there was a significant difference
between CTG and FpO2. In evaluating pH from the umbilical artery (pH < 7.20), TCG proved
to be most sensitive again but displayed low specificity. STAN was the best predictor of newborns with
normal pH. In evaluating high levels of lactate (> 3.7mmol/L) and BE (> - 10) and related demonstration
of metabolic acidosis STAN proved to be the best predictor. The condition of the newborn evaluated
by a neonatologist immediately after birth (medium or heavy depression) was best predicted by FpO2. In
deliveries performed by Cesarean section and after the administration of tocolysis the postnatal pH was
higher then in forceps deliveries without acute tocolysis. The occurrence of emergencies in the course of
a pathological delivery in individual methods is as follows: CTG, FpO2 and STAN.
Conclusion: Even though CTG displays a very low specificity, this method should not be rejected, since
it draws attention of the obstetrician very early to the possibility of developing hypoxia. FpO2 or STAN
gives more precision to the situation and demarcates a correct moment for ending the delivery for the
indication of fetus hypoxia intra partum. STAN is the best predictor for conditions of developing metabolic
acidosis, evaluated postnatally by the level of lactate and BE in fetal blood.
Key words:
sensitivity, specificity, hypoxia diagnosis, cardiotoxicography, fetal pulse oximetry, ST-analysis
of fetus ECG
|