Does increased resistance on umbilical artery Doppler preclude a trial of labour?

To determine whether patients with increased resistance on umbilical artery Doppler velocimetry could be safely allowed a trial of labour.

The Coombe Womens' Hospital is a university teaching hospital which takes tertiary referrals. All singleton pregnancies found to have increased resistance (>2 SD above the mean for gestational age) on umbilical artery Doppler ultrasound between 1993 and 1995 inclusively were identified from the ultrasound database and reviewed, retrospectively. Cases where the umbilical artery waveform reverted to normal or deteriorated to absent end diastolic flow on a subsequent scan were excluded. The 118 cases identified were divided into two groups, those that were delivered by elective caesarean section and those that laboured.

Forty-five patients were delivered by elective caesarean section and 73 were allowed to labour. In the group that laboured over 90% delivered vaginally and 9.8% were delivered by emergency caesarean section. Three babies had a cord pH less than 7.20 in the group that laboured. Two babies had an Apgar score of less than 7 at 5 min in the group that were delivered electively. There were no neonatal seizures or perinatal deaths in either of the two groups.

This study shows that patients with increased resistance on umbilical artery Doppler can be allowed a trial of labour without compromising the fetal outcome. We would suggest that consideration be given to induction of labour in selected patients as an alternative to elective section.