Longitudinal change in cerebroplacental ratio in small-for-gestational-age fetuses and risk of stillbirth

OBJECTIVE

To investigate whether assessment of longitudinal change in Doppler variables in small-for-gestational-age (SGA) fetuses improves the prediction of those at risk of stillbirth.

METHODS

This was a longitudinal study of two cohorts of singleton pregnancies, which included SGA and appropriate-for-gestational-age (AGA) fetuses, respectively. The inclusion criteria for the SGA cohort were singleton pregnancy at ≥ 20 weeks' gestation, classified as SGA (estimated fetal weight < 10^th centile). The AGA cohort consisted of singleton pregnancies deemed at high risk of being SGA, which were followed up longitudinally but remained AGA. Fetal middle cerebral artery (MCA) pulsatility index (PI) and umbilical artery (UA)-PI were measured longitudinally and cerebroplacental ratio (CPR) was calculated, and values were converted to multiples of the median. The last two measurements prior to delivery were included in the analysis. Longitudinal models for Doppler variables were developed using linear-mixed models and their accuracy in the prediction of stillbirth was tested using generalized linear models. A Bayesian framework was employed to compare the accuracy of longitudinal and standard (last-scan measurement) models.

RESULTS

In total, 1549 AGA and 941 SGA pregnancies were included in the analysis. There were 30 (3.2%) and no stillbirth cases in the SGA and AGA groups, respectively. Change in MCA-PI, UA-PI and CPR with advancing gestation was significantly different between liveborn AGA and SGA fetuses, with a less pronounced difference with advancing gestation. Using the last measurement, the best models for the prediction of stillbirth in SGA pregnancies were those based on CPR (accuracy, 75.0%; 95% CI, 72.6-77.2%) and UA-PI (accuracy, 71.0%; 95% CI, 68.6-73.4%). The posterior probability of the standard CPR model having a higher accuracy compared with the UA-PI model was 97.2% (magnitude of change (MC), 3.9%; 95% credible interval (CrI), 0.5-7.3%). The accuracies of the standard, compared with the longitudinal, models for UA-PI (71.0% vs 72.8%), MCA-PI (64.6% vs 63.8%) and CPR (75.0% vs 74.9%) in the prediction of stillbirth were not significantly different. The posterior probabilities for improvement in accuracy using longitudinal, compared with standard, assessment were 50.1% (MC, < 0.1%; 95% CrI, -3.3 to 3.3%), 35.2% (MC, -0.1%; 95% CrI, -4.5 to 2.8%) and 82.2% (MC, 1.9%; 95% CrI, -1.5 to 5.3%) for CPR, MCA-PI and UA-PI models, respectively. Therefore, change in Doppler parameters did not improve the accuracy of the prediction of stillbirth, compared with that of the last-scan measurement.

CONCLUSION

Longitudinal assessment of Doppler parameters was not useful in improving the detection of stillbirth in SGA pregnancies, as compared with a single-point assessment. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Placental histopathology associated with pre-eclampsia: systematic review and meta-analysis

OBJECTIVE

Pre-eclampsia (PE) is associated with impaired trophoblastic invasion and typical villous and vascular placental lesions. The primary aim of this study was to quantify the prevalence of placental histopathological lesions in pregnancies complicated by PE.

METHODS

MEDLINE, EMBASE and CINAHL were searched electronically, and relevant articles reporting on placental histopathological lesions were assessed according to the following criteria: study design, number of pregnancies included, severity of PE and whether the pathologist was blinded to the clinical information. Prospective and retrospective case-control studies including ≥ 100 pregnancies were included in the systematic review. The incidence of each type of histological lesion according to the Perinatal Section of the Society for Pediatric Pathology classification in pre-eclamptic and normal pregnancies was identified, and lesions were categorized into two main groups: villous lesions and vascular lesions. Random-effects meta-analysis of proportions was used for analysis. Between-study heterogeneity was assessed using the I² statistic.

RESULTS

The search yielded 717 citations, and a total of eight studies (four blinded and four non-blinded) were included in the review. In unblinded studies, the pooled prevalence of villous lesions was 11.6% and 48.2% in normal and pre-eclamptic pregnancies, respectively, giving a pooled odds ratio (OR) of 7.59. In blinded studies, the pooled prevalence of villous lesions was 18.5% and 42.0% in normal and pre-eclamptic pregnancies, respectively, giving a pooled OR of 4.28. In unblinded studies, the pooled prevalence of vascular lesions was 8.1% and 37.3% in normal and pre-eclamptic pregnancies, respectively, giving a pooled OR of 20.34. In blinded studies, the pooled prevalence of vascular lesions was 9.8% and 38.9%, in normal and pre-eclamptic pregnancies, respectively, giving a pooled OR of 7.08.

CONCLUSIONS

In blinded studies, the incidence of both placental villous and vascular histopathological lesions is four- to seven-fold higher in pre-eclamptic than in normal pregnancies. Greater differences are reported in unblinded studies. Despite the higher probability (point prevalence) of finding abnormal placental pathology in pregnancies with PE, placental lesions are not specific to the diagnosis of PE. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.