Outcomes of common arterial trunk (CAT) depend mainly on truncal valve function, coronary artery abnormalities and presence of interrupted aortic arch. Little is known about the precision and potential impact of prenatal diagnosis of CAT in the current era.

Retrospective analysis of all prenatally diagnosed CAT patients with postnatal or fetopsy confirmation from 2011–2019 in a single tertiary center. Cohen's Kappa statistic was used to measure agreement for pre- and postnatal assessment of anatomic subtypes according to Van Praagh and of truncal valve function. Mortality and morbidity variables were compared.

Eighty-four patients (62 live born with prenatal diagnosis/16 live born with postnatal diagnosis/6 terminations of pregnancy with fetopsy) met inclusion criteria. Diagnostic precision for prenatal diagnosis of CAT subtypes was moderate (Kappa κ=0.43) with a pre- and postnatal discordance in 19%. Notably, no fetus had a prenatal diagnosis of CAT Type A3, and only half of patients with CAT Type A4 (8/17) were diagnosed prenatally. Fetal evaluation of truncal valve function underestimated the presence and severity of insufficiency (slight agreement; κ=0.19). However, 4 of 5 postnatally confirmed significant stenoses were diagnosed prenatally (moderate agreement; κ=0.38). There was no difference in postoperative mortality for CAT patients with or without prenatal diagnosis (P=0.87). CAT patients with fetal diagnosis underwent earlier intervention (P≤0.001), had shorter intubation time (P=0.047) and shorter global hospital stay (P=0.01).

The precision of prenatal diagnosis of CAT has to be improved. Anatomic subtypes A3/A4 are largely underdiagnosed with potential negative impact on neonatal management. Truncal valve dysfunction appears difficult to assess, even if valve stenosis seems easier predictable than insufficiency. Prenatal diagnosis of CAT has no impact on postoperative mortality but tends to favorably influence morbidity.