ABSTRACTWe report on a fetal case of Ebstein's anomaly with severe tricuspid regurgitation, functional pulmonary atresia and progressive circular shunting (CS) across a widely patent ductus arteriosus (DA) and regurgitant pulmonary valve, contributing to significant systemic hypoperfusion. To mitigate the extent of CS and allow the pregnancy to continue, maternal non‐steroidal anti‐inflammatory drug (NSAID) therapy with indomethacin was started at 33 + 5 weeks to induce DA constriction. Rather than achieving the desired narrowing of the DA, the treatment led to its complete closure and only minimal antegrade flow across the pulmonary valve. While closure of the DA resulted in the anticipated improvement in fetal hemodynamics, at birth, the child was at risk of severe hypoxemia and its consequences due to the lack of adequate pulmonary perfusion. Reduction and eventual discontinuation of the NSAID treatment did not result in DA reopening. Our experience illustrates the risk of unintended irreversible DA closure when NSAIDs are used to treat CS. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.