Rate of deterioration of umbilical artery Doppler indices in fetuses with severe early-onset fetal growth restriction.

BACKGROUND

Incorporation of umbilical artery Doppler in the surveillance of fetal growth restriction has been shown to reduce the risk of perinatal deaths. Systole/Diastole ratio, Pulsatility Index and Resistance Index are obtained upon Doppler interrogation of the umbilical artery however it is unknown which index predicts more advanced stages of placental deterioration.

OBJECTIVE

This study aimed to examine risk factors for the development of absent or reversed end-diastolic velocity and the time intervals of deterioration from normal umbilical artery end-diastolic velocity (indicated by systole/diastole ratio, pulsatility index, or resistance index) to decreased and absent or reversed end-diastolic velocity in fetuses with early-onset severe fetal growth restriction.

STUDY

DESIGN

This was a retrospective cohort study performed from 2005 to 2020. All singleton pregnancies with severe (estimated fetal weight or abdominal circumference below the third percentile) and early-onset (diagnosed between 20 0/7 and 31 6/7 weeks of gestation) fetal growth restriction were included. Patients with fetal genetic or structural anomalies, suspected congenital infections, absent or reversed end-diastolic velocity at diagnosis, poor pregnancy dating, and absence of follow-up ultrasounds were excluded. Estimated fetal weight, abdominal circumference, and Doppler indices were reviewed longitudinally from diagnosis to delivery. To examine risk factors for absent or reversed end-diastolic velocity, we performed backward stepwise logistic regression and calculated odds ratios with 95% confidence intervals. Kaplan-Meier curves were compared using log-rank tests.

RESULTS

A total of 985 patients met the inclusion criteria, and 79 (8%) progressed to absent or reversed end-diastolic velocity. Factors associated with development of absent or reversed end-diastolic velocity included gestational age at diagnosis (adjusted odds ratio, 4.88 [95% confidence interval, 2.55-9.37] at 20 0/7 to 23 6/7 weeks; adjusted odds ratio, 1.56 [95% confidence interval, 0.86-2.82] at 24 0/7 to 27 6/7 weeks compared with 28 0/7 to 31 6/7 weeks) and presence of chronic hypertension (adjusted odds ratio, 2.37 [95% confidence interval, 1.33-4.23]). Rates of progression from diagnosis of fetal growth restriction with normal umbilical artery Doppler to absent or reversed end-diastolic velocity were significant after 4 weeks from diagnosis (5.84% [95% confidence interval, 4.50-7.57]). Regarding the Doppler indices, the progression from normal values to abnormal indices was similar at 1 and 2 weeks. However, the rate of progression from normal to abnormal systole/diastole ratio compared with the rates of progression from normal to abnormal pulsatility index or resistance index was higher at 4 and 6 weeks. Deterioration from abnormal indices to absent or reversed end-diastolic velocity was shorter with abnormal resistance index and pulsatility index when compared with the systole/diastole ratio at 2, 4, and 6 weeks after diagnosis and at 6 weeks, respectively.

CONCLUSION

Earlier gestational age at diagnosis and chronic hypertension are considered as risk factors for Doppler deterioration and development of absent or reversed end-diastolic velocity in the umbilical artery. With normal Doppler indices, significant deterioration and progression to absent or reversed end-diastolic velocity is unlikely until 4 weeks after diagnosis. Abnormal systole/diastole ratio seems to appear first. However, abnormal pulsatility index or resistance index was associated with absent or reversed end-diastolic velocity.