Background: Ductus arteriosus aneurysm is a rare fetal disorder.
Case: A 35-year-old primigravida had an uneventful antenatal course. Ultrasound examination at 30 weeks of gestation revealed hydramnios. The fetal ductus arteriosus became saccular and dilated with turbulent flow and diameter of 2.5 cm. It was located at the left upper thorax, just distal to the pulmonic valve and extended to the thoracic aorta. A ductus arteriosus aneurysm was diagnosed prenatally. Five days after diagnosis, preterm labor occurred, and dexamethasone and terbutaline were administered. Six hours after initiation of terbutaline, the fetal heart rate suddenly dropped to 90 beats per minute (bpm). A bedside ultrasound examination performed immediately showed profound bradycardia. The aneurysm became a heterogeneous hypoechoic mass with no pulsation, and the fetal heart rate suddenly disappeared.
Conclusion: Ductus arteriosus aneurysm can be diagnosed prenatally, and terbutaline or dexamethasone may be associated with a risk for rupture.