May-Thurner Syndrome Is Aggravated by Pregnancy.

This study aims to emphasize that asymptomatic patients with undiagnosed and asymptomatic May-Thurner syndrome (MTS) may firstly develop severe compression during pregnancy. A 40-year-old woman, G1P0, at 22 weeks of twin gestation presented with left lower extremity edema and pain. One twin was structurally normal while the other had bilateral renal agenesis with oligohydramnios. Magnetic resonance venography (MRV) revealed severe compression of the left iliac vein by the right iliac artery without evidence of deep vein thrombosis (DVT). Conservative treatment with anticoagulant prophylaxis was instituted throughout the rest of pregnancy and postpartum period. She was also complicated with severe pre-eclampsia, a cesarean section was performed due to a prolapsed cord at 27 weeks of gestation, and she gave birth to a surviving baby weighing 1100 g. In conclusion, this case report provides evidence that pregnancy can disclose a subtle May-Thurner anatomy to be symptomatic without DVT. Successful pregnancy outcomes could be achieved with conservative treatment and anticoagulant prophylaxis.