Clinical impact of Doppler reference charts on management of small‐for‐gestational‐age fetuses: need for standardization

Abstract

Objective To assess clinical variability in the management of small‐for‐gestational‐age (SGA) fetuses according to different published Doppler reference charts for umbilical artery (UA) and fetal middle cerebral artery (MCA) Doppler indices and cerebroplacental ratio (CPR). Methods We performed a systematic search of MEDLINE, EMBASE, CINAHL and the Web of Science databases from 1954 to 2018 for studies with the sole aim of creating fetal Doppler reference values for UA, MCA and CPR. The top cited articles for each Doppler parameter were included. Variability in Doppler values at the following clinically relevant cut‐offs was assessed: UA‐pulsatility index (PI) > 95th percentile; MCA‐PI < 5th percentile; and CPR < 5th percentile. Variability was calculated for each week of gestation and expressed as the percentage difference between the highest and lowest Doppler value at the clinically relevant cut‐offs. Simulation analysis was performed in a cohort of SGA fetuses (n = 617) to evaluate the impact of this variability on clinical management. Results From a total of 40 studies that met the inclusion criteria, 19 were analyzed (13 for UA‐PI, 10 for MCA‐PI and five for CPR). Wide discrepancies in reported Doppler reference values at clinically relevant cut‐offs were found. MCA‐PI showed the greatest variability, with differences of up to 51% in the 5th percentile value at term. Variability in the 95th percentile of UA‐PI and the 5th percentile of CPR at each gestational week ranged from 21% to 41% and 15% to 33%, respectively. As expected, on simulation analysis, these differences in Doppler cut‐off values were associated with significant variation in the clinical management of SGA fetuses, despite using the same protocol. Conclusions The choice of Doppler reference chart can result in significant variation in the clinical management of SGA fetuses, which may lead to suboptimal outcomes and inaccurate research conclusions. Therefore, an attempt to standardize fetal Doppler reference ranges is needed. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

ISUOG Practice Guidelines: diagnosis and management of small‐for‐gestational‐age fetus and fetal growth restriction

“…Even among studies with a high methodological quality score, there are significant differences in the definition of 'normality' and normal ranges 46 . A recent study evaluating the 10 most-cited articles providing reference ranges for MCA-PI, UA-PI and cerebroplacental ratio (CPR), found wide discrepancies in Doppler reference values that accounted for a variability of up to 50% in the 5 th percentile cut-off value of MCA-PI at term 47 . Similarly, the study found significant differences in the cut-off for UA-PI above the 95 th percentile (20-40%) and CPR below the 5 th percentile (15-35%) 47 .…”

“…A recent study evaluating the 10 most-cited articles providing reference ranges for MCA-PI, UA-PI and cerebroplacental ratio (CPR), found wide discrepancies in Doppler reference values that accounted for a variability of up to 50% in the 5 th percentile cut-off value of MCA-PI at term 47 . Similarly, the study found significant differences in the cut-off for UA-PI above the 95 th percentile (20-40%) and CPR below the 5 th percentile (15-35%) 47 . Wide discrepancies have been reported in reference ranges used for biometry, Doppler parameters and birth weight, even at national level in centers with high expertise in the management of FGR, that might significantly impact the diagnosis and management of FGR 48 .…”

“…Table S1 Most relevant studies reporting reference ranges for fetal middle cerebral artery (MCA), cerebroplacental ratio (CPR) and umbilicocerebral ratio (UCR). Adapted from Ruiz-Martinez et al 47…”

Selección de la curva de referencia del índice pulsatilidad de las arterias umbilicales

“…Durante la evaluación de este artículo, Ruiz Martínez (17) publicó un estudio similar que compara el percentil 95 del IP AU de 19 publicaciones diferentes, encontrando variación entre 20 y 40% de este valor crítico entre ellas, a lo largo del embarazo.…”

Fetal cerebral blood‐flow redistribution: analysis of Doppler reference charts and association of different thresholds with adverse perinatal outcome

“…This uncertainty may at least in part be due to the heterogeneity of reference charts for fetal arterial Doppler parameters 16 , and part of this, but not all, could be explained by methodological shortcomings. Ruiz-Martinez et al performed a simulation analysis in a cohort of small for gestational age (SGA) fetuses using percentile thresholds from 10 most frequently cited arterial Doppler reference charts (UA-PI, MCA-PI and CPR) 17 . They concluded that the variation in percentile thresholds could result in a large variation in clinical management.…”