Retrospective diagnosis and characterisation of fetal CHD at the Fetal Exploration Unit, Guillermo Grant Benavente Hospital, Chile

BACKGROUND: Prenatal diagnosis of CHD is essential for counseling, perinatal management, and planning surgical strategies. Data from southern Chile are scarce. METHODS: We conducted a retrospective, observational, descriptive study of all cases with a confirmed prenatal diagnosis of moderate or complex CHD at the Fetal Exploration Unit, Guillermo Grant Benavente Hospital, between January 2018 and March 2025. Maternales variables, fetal echocardiographic findings, genetic studies, and neonatal outcomes were analysed. Survival was estimated using Kaplan-Meier curves. RESULTS: Eighty cases were analysed, one with complete atrioventricular block requiring pacemaker implantation and 79 with structural CHD. Male fetuses accounted for 63.8%. The most frequent entities were isolated or associated transposition of the great arteries (24.1%), hypoplastic left heart syndrome (16.5%), and coarctation of the aorta (10.1%). Twenty-one diagnostic combinations (26.6%) were documented, the most common being double-outlet right ventricle with transposition of the great arteries. Genetic testing was performed in 39 cases (48.8%), revealing chromosomal anomalies in 13 (16.3%). Maternal comorbidities were recorded in 27 pregnancies (33.8%), notably diabetes and hypothyroidism. Seventy percent of patients underwent neonatal cardiac surgery. Seventeen deaths (21.3%) occurred: one stillbirth and 16 postnatal deaths, of which 13 were neonatal. Overall survival at follow-up was 78.8%. Kaplan-Meier analysis showed a marked drop in the first month of life, stabilising thereafter at ∼81%. CONCLUSIONS: Findings highlight a high prevalence of critical lesions, a relevant proportion of chromosomal abnormalities, and a notable association with maternal hypothyroidism. Survival reflects advances in prenatal diagnosis and neonatal cardiac surgery, although challenges remain for non-surgical cases.