Use of umbilical-cerebral Doppler ratios in predicting fetal growth restriction in near-term fetuses

Analysis of the Correlation/Agreement of Maternal-fetal Doppler Parameters in Normal and Growth-Restricted Fetuses

OBJECTIVE

 To assess the degree of correlation/agreement of maternal-fetal Doppler parameters between normal and growth-restricted fetuses (fetal growth restriction [FGR]).

METHODS

 The present observational and retrospective study included 274 singleton pregnancies. The following maternal-fetal Doppler parameters were assessed: uterine artery (UAt), umbilical artery (UA), middle cerebral artery (MCA), cerebroplacental ratio (CPR), and umbilical-cerebral ratio (U/C). The assessment of FGR was based on the Figueiras and Gratacós9 criteria. Spearman correlation coefficients were estimated to assess the correlation between resistance (RI) and pulsatility (PI) indices of Doppler parameters. The agreement between two Doppler parameters was assessed by the Kappa coefficient.

RESULTS

 In total, 502 Doppler examinations were included, and FGR was observed in 19 out of 274 fetuses. A strong correlation was observed between RI and PI of UAt, UA, and MCA in all of the samples (p < 0.001). Of the 502 Doppler examinations, there was agreement between U/C and CPR percentiles for 480 (95.6%) and disagreement for 22 (4.4%), with Kappa coefficient of 0.26, thereby corresponding to weak agreement. Of the 68 cases with estimated fetal weight ≤ 9^th percentile (small for gestational age [SGA]), there was agreement between U/C > 1.0 and CPR < 5^th percentile in 61 (88.4%) and disagreement in 7 (5.8%) with Kappa coefficient of 0.49, thereby corresponding to moderate agreement.

CONCLUSION

 Strong correlation was observed among RI and PI UAt, UA, and MCA Doppler examinations in the present study; however, weak agreement was observed between U/C and CPR in the normal and FGR fetuses. In SGA, U/C and CPR demonstrated moderate agreement.

Doppler study of the fetal vertebral artery in small for gestational age fetuses with intrauterine growth restriction

OBJECTIVES

The purposes of this study were to evaluate the Doppler resistive index of the fetal vertebral artery in small for gestational age (SGA) fetuses and to examine the ability of the vertebral artery resistive index in the diagnosis of intrauterine growth restriction (IUGR).

METHODS

A total of 437 Doppler examinations of the vertebral and umbilical artery resistive indices were performed in 437 fetuses between 26 and 41 weeks' gestation. According to birth weight, fetuses were classified into 5 groups: 1, above the 10th percentile; 2, between the 10th and 5th percentiles; 3, between the 5th and 3rd percentiles; 4, below the 3rd percentile; and 5, below the 3rd percentile with an umbilical artery resistive index above the 95th percentile. Subsequently, vertebral artery resistive index values were converted into multiples of the median, and box and whisker charts were generated to evaluate differences. Finally, receiver operating characteristic curves were calculated to assess the accuracy of the vertebral artery resistive index for predicting IUGR and a low Apgar score.

RESULTS

Compared to normally grown fetuses, vertebral artery resistive index values were lower in fetuses with birth weight below the 3rd percentile, and this difference was greater in fetuses with birth weight below the 3rd percentile and Doppler anomalies of the umbilical artery. The receiver operating characteristic analysis showed that the vertebral artery resistive index diagnosed SGA fetuses and low Apgar scores poorly. However, it performed better in cases of severe IUGR with high umbilical artery resistive index values.

CONCLUSIONS

Preliminary data show that the vertebral artery resistive index diminishes in growth-restricted SGA fetuses. Doppler examination of the vertebral artery seems to identify a group of fetuses with brain sparing and severe IUGR.

The role of Doppler and placental screening

Placental-associated diseases account for most cases of adverse perinatal outcome in developing countries. Uterine Doppler evaluation predicts most instances of early-onset preeclampsia and intrauterine growth restriction, but there is no evidence in favour of any prophylactic strategy in cases of an abnormal screening result. Umbilical artery Doppler investigation allows identifying those small-for-gestational-age foetuses at higher risk, and its use in these pregnancies improves a number of perinatal outcomes. Middle cerebral artery Doppler investigation reflects brain redistribution, and its use in combination with the umbilical artery in a cerebroplacental ratio seems to improve prediction of adverse outcome, mainly in near-term pregnancies, where most instances of adverse outcome occur in foetuses with normal umbilical artery. Ductus venosus Doppler waveform is a surrogate parameter of the foetal acid-base status. However, the benefits of its use in the management of early-onset growth restriction needs further evidence.

Growth deficit in term small-for-gestational fetuses with normal umbilical artery Doppler is associated with adverse outcome

AIM

The association between the growth deficit and the occurrence of adverse outcome was analyzed in a cohort of small-for-gestational age fetuses delivered at term.

METHODS

A cohort of consecutive singleton fetuses suspected of being SGA during the late third trimester and delivered beyond 37 weeks was selected. Growth deficit area was calculated as that between the individual 10(th) centile curve of the customized optimal fetal weight and the individual fetal growth curve.

RESULTS

A total of 55 women were included. Of these, 16 had 28 adverse events: eight cases of umbilical artery pH<7.15, 9 cases of caesarean section for fetal distress and 11 cases of admission to neonatal intensive care unit. Whereas the mean area of growth deficit was 8.8 kg x week units (SD 7.6) for cases with normal outcomes, it was 13.9 (SD 8.04) for cases with adverse outcomes (P=0.03). A growth area deficit >10 units, predicted the occurrence of adverse outcome with a sensitivity and specificity of 62% and 68%, respectively.

CONCLUSION

In term growth restricted fetuses the degree of growth deficit from the optimal customized growth may be used to identify a subgroup of fetuses at high-risk for adverse outcomes.