Computerized cardiotocography in the management of intrauterine growth restriction associated with Doppler velocimetry alterations.

OBJECTIVE

To verify the reliability of computerized cardiotocography (cCTG) in the prediction of the oxygen metabolism status of fetuses with growth restriction and Doppler velocimetry alterations.

METHODS

From 24 third-trimester cesarean section performed because of intrauterine growth restriction (IUGR) and Doppler velocimetry alterations, there were 11 cases of fetal heart rate alterations (Dawes-Redman criteria were not satisfied) and 13 cases of reactive cCTG. Fetal lung maturity was detected by amniocentesis and blood samples for umbilical blood gas analysis (UBGA) were collected before the first neonatal breath from the umbilical artery in a double-clamped segment of the cord.

RESULTS

Umbilical cord gas analysis showed arterial cord blood pH to be 7.20 or less in 11 newborns (45.8%), 7.10 or less in 6 (25%), and 7.00 or less in 3 (12.5%). Linear regression analysis showed short-term variation (STV) in the fetal heart rate to be significantly correlated with umbilical artery pH (r = 0.49; P = 0.01) and pCO2 (r = -0.50; P = 0.01). There were no significant correlations between cCTG and the other UBGA parameters considered. Receiver operator curves permitted to calculate the STV values at which pathological neonatal UBGA values can be expected (pH < 7.00 and pCO2 > 80 mmHg). A short-term variation less than 4.5 ms was found to predict acidemia with a sensitivity of 100% and a specificity of 70% (positive predictive value, 33%; negative predictive value, 100%), and hypercarbia with a sensitivity of 100% and a specificity of 77.8% (positive predictive value, 55.6%; negative predictive value, 100%).

CONCLUSION

In view of the results of this study, 4.5 ms for STV may be a threshold below which timing of delivery should be decided in cases of fetal growth restriction.