Acute type B aortic dissection in a pregnant woman with undi
• Type B aortic dissection during pregnancy can extend under medical treatment.

• Aortic dissection in pregnant women may require aggressive obstetric intervention.

• Marfan syndrome should be diagnosed before pregnancy to prevent aortic dissection.

Aortic dissection during pregnancy is rare but can be life-threatening to both the mother and the foetus. Marfan syndrome is a major risk factor for acute aortic dissection during pregnancy. A woman who had not been diagnosed with Marfan syndrome prior to pregnancy and who developed acute type B dissection at 32 weeks of gestation reported. The maternal hemodynamic status was stable, and fetal well-being was ensured. However, under conservative treatment, the dissection extended to the descending aorta, reaching the bilateral iliac artery 2 days later. Due to fetal distress, preterm delivery was performed via cesarean section. The primary treatment of type B aortic dissection is conservative medical treatment, with the goals of hemodynamic stabilization, minimizing the extent of the dissection, and decreasing the risk of rupture. However, type B aortic dissection, even the uncomplicated type, in pregnant women may require early and aggressive obstetric interventions to improve maternal and fetal prognoses.