Uterine Artery Doppler useful screening tool for women high risk for Fetal Growth Restriction
Fetal growth restriction (FGR) is one of the leading causes of stillbirth; hence, detection and monitoring of pregnancies that are high risk for FGR is key in reducing adverse pregnancy outcomes. Reducing stillbirth is a national priority, and there has been concerted effort to detect and improve the care of women and babies at risk of FGR and stillbirth. In order to achieve this, a number of national initiatives are undertaken.
Version two of the Saving Babies’ Lives Care Bundle (SBLCBv2) has been produced to build on the achievements of version one and is the next step on the journey towards meeting the national ambition to halve stillbirths and neonatal baby deaths by 2025. The updated element 2 of SBLCBv2 focuses more attention on pregnancies at highest risk of FGR, recognises the importance of adequate risk assessment of all women, and has introduced the Uterine Artery Doppler (UtAD) screening tool to help triage women at high risk for placental dysfunction.
One of the commonly used indices in UtAD studies is pulsatility index (PI), and this is calculated by subtracting the end diastolic flow from the peak systolic flow and dividing it by the mean. Low end diastolic velocities and early notch are the characteristic waveforms of the uterine artery in nonpregnant women and pregnant women in the first trimester. Persistent notching or abnormal velocity ratio is a reflection of increased impedance in the vessel and are associated with inadequate trophoblastic invasion. Accuracy in the prediction of FGR is fundamental in the efficient allocation of resources for monitoring and prevention of adverse perinatal outcomes. The SBLCBv2 uses the PI value of UtAD for the surveillance of women at an increased risk of FGR. However, the predictive accuracy of UtAD has been greeted with mixed reactions and its value as a predictive tool has also been questioned.
The SBLCBv2 was implemented at the United Lincolnshire Hospital NHS Trust (ULHT) on 1st of September 2020. The aims of study by Emmanuel Ekanem et al were to (1) determine the prevalence of FGR and (2) evaluate the outcomes of pregnancies identified as high risk for FGR.
One-year retrospective cohort study (1st September 2020-31st August 2021) was conducted across both ULHT hospitals in the UK (Lincoln County Hospital in Lincoln and Pilgrim Hospital in Boston).
During the study period, 5197 women were booked at ULHT. Of 5197, 349 were identified as high risk for FGR. When numbers were compared for the two hospitals, FGR rate was higher in Lincoln 8.10% vs. 4.51% in Boston. In addition, an increased proportion of abnormal UtAD scans was observed in Lincoln (35.7%) vs. in Boston (22%) (P = 0:014).
Of the 349 UtAD scans, 237 were normal (67.9%), 41 showed unilateral notching (11.7%), 43 bilateral notching (12.3%), and 28 raised PI (8%). Babies in the bilateral notching group exhibited the lowest birth weight (P = 0:005), born at an earlier gestation (P = 0:029), and with low Apgar scores at 1 (P = 0:007) and 5 minutes (P < 0:001).
FGR is a significant cause of perinatal morbidity and mortality, and despite advances in obstetric care, management of FGR remains a major problem in developed countries. Risk assessment in early pregnancy is important to triage the care of women at increased risk of FGR, and this can be done using UtAD screening in the second trimester between 20 and 24 weeks. This study demonstrated that all women booked at ULHT were risk assessed for FGR in accordance to the SBLCBv2 and were offered appropriate clinical pathway for FGR surveillance. The commonest indication for classifying women as high risk for FGR was a previous history of FGR, followed by low PAPP-A (pregnancy-associated plasma protein A) and hypertensive diseases in previous pregnancies. Other indications for undertaking UtAD scans are outlined in the supplementary file. Authors found a high prevalence of FGR at ULHT (6.7%), particularly at Lincoln (8.1%) compared to the figure reported in literature (3-7%).
In summary, the study supports the implementation of UtAD for predicting high-risk FGR pregnancies destined for adverse outcome and enabled to stratify the intensity of fetal surveillance. However, the debate over whether to use uterine artery PI alone or in conjunction with notching continues and more research are required to support or refute the use of uterine artery notching in screening women at high risk for FGR. Nonetheless, based on study findings, authors advise uterine artery notching to be reported in clinical practice for appropriate counselling and managing pregnancies at high risk of FGR.
Soure: Emmanuel Ekanem,1 Faris Karouni,2 Emmanuoil Katsanevakis,1 and Habiba Kapaya; Hindawi Journal of Pregnancy Volume 2023, https://doi.org/10.1155/2023/1506447
