Longitudinal Assessment of Fetal Ductus Arteriosus Morphometry: Establishing Gestational Age-Specific Reference Values

Abstract

OBJECTIVES: To longitudinally evaluate fetal ductus arteriosus (DA) morphometric changes and establish normative reference values between 18 and 36 weeks of gestation.

STUDY DESIGN: This prospective cohort study included 29 pregnant women with structurally normal singleton fetuses and confirmed gestational ages. Each participant underwent serial standardized ultrasound examinations to evaluate DA length and proximal, mid, and distal diameters. We defined weekly growth trends using regression analyses and assessed correlations with fetal biometric parameters.

RESULTS: Due to missed examinations caused by intermittent withdrawals, a total of 99 prenatal and 29 postnatal ultrasound examinations were performed longitudinally. DA length increased linearly at approximately 0.63 mm/week (R²=0.813). Proximal, mid, and distal diameters showed significant linear increases of 0.28 mm/week, 0.32 mm/week, and 0.16 mm/week, respectively (R²=0.769, 0.681, and 0.541). DA length correlated strongly with fetal abdominal circumference (R²=0.855). We established reference percentile tables and normative curves for DA dimensions across gestational ages (18-36 weeks).

CONCLUSIONS: This longitudinal study provides comprehensive reference values for fetal DA morphometric assessment between 18-36 gestational weeks. These nomograms support clinicians in identifying deviations suggestive of DA constriction, especially relevant given the expanded indications for maternal indomethacin administration. Further multicentre studies involving diverse populations are required to enhance the generalizability and clinical applicability of these reference standards.