Non-invasive prenatal diagnosis of congenital cytomegalovirus infection using maximum trophoblast thickness and biomarkers in maternal blood and urine in first trimester.

Abstract

Congenital cytomegalovirus (CMV) infection, a leading cause of sensorineural hearing loss and neurological impairment, is typically diagnosed by second-trimester amniocentesis, delaying clinical decision-making. This study aimed to assess the predictive value of maximum trophoblast thickness (MTT) measured by first-trimester three-dimensional (3D) ultrasound, in combination with maternal biomarkers, for the early prediction of CMV vertical transmission. This was a retrospective cohort study of pregnant women, not previously seropositive for CMV, who were referred to Necker-Enfants malades Hospital between October 2019 and May 2024 for maternal primary infection (MPI) with CMV in early pregnancy. Multiple pregnancies and fetuses with genetic anomaly were excluded. MTT measurement was performed using 3D multiplanar ultrasound between 11 + 0 and 14 + 6 weeks' gestation by two independent observers. Interobserver agreement for MTT measurement was assessed using the intraclass correlation coefficient (ICC). We recorded maternal characteristics, including first-trimester maternal biomarkers (pregnancy-associated plasma protein-A, free β-human chorionic gonadotropin and placental growth factor) and CMV polymerase chain reaction (PCR) status in the maternal blood and urine. Vertical transmission was confirmed by CMV-PCR in chorionic villi (CV) and/or amniotic fluid (AF). The predictive value of MTT, alone and in combination with relevant covariables, was assessed using logistic regression models and receiver-operating-characteristics (ROC)-curve analysis. A total of 127 pregnant women with a median gestational age (GA) at CMV-MPI of 2.0 (interquartile range, -2.5 to 7.0) weeks were included, of whom 120 (94.5%) received valacyclovir for secondary prevention. CMV-PCR was positive in 7.1% of CV samples (median GA at sampling, 13.7 weeks) and 9.4% of AF samples (median GA at sampling, 17.4 weeks). MTT was significantly higher in cases with a positive CMV-PCR result in AF compared to those with a negative result (median, 21.3 mm vs 17.1 mm; P = 0.017). The ICC for MTT measurement was 0.827 (95% CI, 0.763-0.875), indicating good interobserver reproducibility. ROC-curve analysis identified 19.0 mm as the optimal MTT threshold, yielding a sensitivity of 83.33% (95% CI, 62.25-100%) for predicting vertical transmission. When combined with CMV-PCR positivity in the maternal blood in the first trimester and delayed valacyclovir initiation beyond 10 weeks, the predictive model achieved an area under the ROC curve of 0.94 (95% CI, 0.87-0.99) for CMV-PCR positivity in AF, with a sensitivity of 80.00% (95% CI, 44.39-97.48%), specificity of 93.26% (95% CI, 85.90-97.49%), positive predictive value of 57.14% (95% CI, 36.71-75.40%) and negative predictive value of 97.65% (95% CI, 92.31-99.31%). Increased MTT measured by 3D ultrasound in the first trimester is associated with CMV vertical transmission and may serve as an early non-invasive marker. Combining MTT with CMV-PCR status in the maternal blood and timing at initiation of treatment improves predictive accuracy and could guide early counseling and targeted invasive testing. © 2025 International Society of Ultrasound in Obstetrics and Gynecology.