Comparative Study of Abdominal Versus Transvaginal Ultrasound for Uterine Artery Doppler Velocimetry at 11 to 13 Weeks

Performance of Fetal Medicine Foundation algorithm for first trimester preeclampsia screening in an indigenous south Asian population

Background

To evaluate the performance of the Fetal Medicine Foundation (FMF) preterm preeclampsia (PE) screening algorithm in an indigenous South Asian population.

Methods

This was a prospective observational cohort study conducted in a tertiary maternal fetal unit in Delhi, India over 2 years. The study population comprised of 1863 women carrying a singleton pregnancy and of South Asian ethnicity who were screened for preterm pre-eclampsia (PE) between 11 and 14 weeks of gestation using Mean Arterial Pressure (MAP), transvaginal Mean Uterine Artery Pulsatility Index (UtAPI) and biochemical markers - Pregnancy Associated Plasma Protein-A (PAPP-A) and Placental Growth Factor.. Absolutemeasurements of noted biomarkers were converted to multiples of the expected gestational median (MoMS) which were then used to estimate risk for preterm PE < 37 weeks using Astraia software. Women with preterm PE risk of ≥1:100 was classified as as high risk. Detection rates (DR) at 10% false positive rate were calculated after adjusting for prophylactic aspirin use (either 75 or 150 mg).

Results

The incidence of PE and preterm PE were 3.17% (59/1863) and 1.34% (25/1863) respectively. PAPP-A and PlGF MoM distribution medians were 0.86 and 0.87 MoM and significantly deviated from 1 MoM. 431 (23.1%) women had a risk of ≥1:100, 75 (17.8%) of who received aspirin. Unadjusted DR using ≥1:100 threshold was 76%.Estimated DRs for a fixed 10% FPR ranged from 52.5 to 80% depending on biomarker combination after recentering MoMs and adjusting for aspirin use.

Conclusion

The FMF algorithm whilst performing satisfactorily could still be further improved to ensure that biophysical and biochemical markers are correctly adjusted for indigenous South Asian women.

Variation in the uterine arteries Doppler parameters when obtained transvaginally or transabdominally at different sampling locations

INTRODUCTION

To evaluate differences in Doppler velocimetry parameters when the uterine arteries (UtA) are evaluated transabdominally (TA) at different sampling locations and transvaginally (TV).

MATERIALS AND METHODS

Five hundred and fifty-seven pregnant women were evaluated between 11 and 39 weeks of gestation. The mean UtA pulsatility index (PI) and prevalence of bilateral notching were obtained at four different locations: (1) TA just above the crossing with the iliac artery; (2) TA just below the crossing with the iliac artery; (3) TA well above approximately 3 cm away from the crossing with the iliac artery; and (4) TV at the point closest to the internal cervical os. Measurements obtained just above the external iliac artery were considered the standard for comparison. Differences among different locations per gestational week were calculated.

RESULTS

The mean UtA-PI and prevalence of bilateral notching were similar when the uterine arteries were sampled TA just above or just below the crossing with the external iliac artery. The mean UtA-PI values and prevalence of bilateral notching were significantly higher (p < .0001) when obtained TV and significantly lower when obtained 3 cm above the crossing with the external iliac artery (p = .004), as compared to the standard plane just above the crossing.

CONCLUSION

The mean UtA-PI and prevalence of bilateral notching vary significantly when the uterine arteries are sampled far above the crossing with the external iliac artery or when obtained transvaginally.Key MessageThe predictive performance of the uterine arteries during pregnancy can significantly vary in relation to the approach selected for evaluation and to the location of the Doppler sampling gate.

Quality assessment of uterine artery Doppler measurement in first-trimester combined screening for pre-eclampsia

OBJECTIVE

To assess the quality of mean uterine artery (UtA) pulsatility index (PI) measurement in a first-trimester pre-eclampsia screening program.

METHODS

Consecutive women with a singleton pregnancy attending first-trimester screening for fetal chromosomal abnormalities also had combined screening for pre-eclampsia based on the Fetal Medicine Foundation (FMF) algorithm, at a large practice in Sydney, Australia, from May 2014 to February 2017. Distributions of mean UtA-PI multiples of the median (MoM) on a logarithmic scale were plotted in relation to the normal median with 95% CI for each operator and for each month. Central tendency and dispersion and cumulative sum charts were produced. Mean UtA-PI MoM values between 0.95 and 1.05 were considered ideal and those between 0.90 and 1.10 were considered acceptable. The screen-positive rates for preterm pre-eclampsia in different groups of sonographers according to their mean log₁₀ UtA-PI MoM were calculated and compared using the chi-square test.

RESULTS

A total of 21 010 women attended for first-trimester ultrasound and had screening for pre-eclampsia. The overall median UtA-PI MoM was 1.042 (interquartile range (IQR), 0.85-1.26). Of 46 sonographers, 42 (91.3%) performed more than 50 examinations and, of those, 41 (97.6%) measured UtA-PI within the acceptable range. Sonographers measuring UtA-PI MoM on average below 0.95 and those measuring it above 1.05 had, respectively, lower and higher screen-positive rates when compared with those with measurements within the 0.95-1.05 UtA-PI MoM interval (7.2% and 13.2% vs 11.2%, respectively, P < 0.001).

CONCLUSION

UtA Doppler is measured well among trained operators when following an established protocol. While slight variations are expected, systematic error in this measurement impacts on the screen-positive rate. Therefore, a quality control process should be in place and retraining of staff may be required. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.