EARLY PRENATAL ULTRASOUND DETECTION OF VENTRICULAR SEPTAL DEFECT (VSD): A STANDARDIZED PROTOCOL, CONFIRMATION CRITERIA, AND STRATEGIES TO REDUCE OVERDIAGNOSIS

Ventricular septal defect (VSD) is the most common congenital heart defect and one of the leading reasons for referral to expert fetal echocardiography. Despite continuous improvements in ultrasound equipment and screening protocols, VSD remains a frequent source of diagnostic uncertainty: small defects may be missed, while pseudo‑defects are often misinterpreted as true shunts. In early gestation (late first to early second trimester), the diagnostic challenge is amplified by the “dropout” phenomenon (apparent discontinuity of the septum caused by unfavorable beam–septum geometry), limited spatial/temporal resolution, motion artifacts from atrioventricular valves, and angle dependence of Doppler signals. These factors contribute to overdiagnosis, patient anxiety, unnecessary referrals, and increased burden on expert centers. Therefore, reproducible confirmation criteria and a standardized, quality‑controlled screening workflow are needed.