Umbilical artery velocimetry may influence clinical interpretation of intrapartum cardiotocograms

Abstract

Background: In a previous prospective randomised trial on pregnancies complicated by small-for-gestational-age fetuses fewer operative deliveries for fetal distress were found after antenatal surveillance with umbilical artery Doppler velocimetry (Doppler group) than after surveillance with cardiotocography (CTG group). Despite that, the neonatal outcome was similar in both groups. This raised the question whether the knowledge of the antenatal Doppler results had influenced the obstetric management of labor.

Methods: In this retrospective study 242 intrapartum cardiotocogram tracings, obtained from the above mentioned prospective trial, were re-interpreted by an expert without knowledge of the results in the original study. The re-interpretation was then compared to the original interpretation.

Results: The expert interpreted 18 intrapartum tracings in the Doppler group and 18 in the CTG group as abnormal, whereas the clinicians interpreted only 8 tracings as abnormal in the Doppler group and 18 tracings in the CTG group.

Conclusions: The results of this retrospective study lend support to our hypothesis that the obstetricians in clinical practice are influenced by the knowledge of a normal umbilical Doppler velocimetry when interpreting an intrapartum CTG. This finding may partly explain why there were fewer emergency cesarean sections for fetal distress in the Doppler group than in the CTG group in the original prospective study.