An Unusual Presentation of Deep Vein Thrombosis

May–Thurner syndrome (MTS) usually presents as acute or chronic deep vein thrombosis (DVT) in patients. A 49-year-old woman presented with left lower limb DVT, which was followed by a diagnosis of MTS on a background of polycystic ovary syndrome (PCOS) and hypothyroidism. MTS is more common among women in the second to fourth decades of life. An endovascular approach is the preferred first-line treatment for MTS. LEARNING POINTS: This case highlights the importance of serial ultrasound Doppler scans in cases where the probability of deep vein thrombosis (DVT) is high as a negative initial Doppler scan does not exclude DVT. May–Thurner syndrome (MTS) should be suspected especially in younger patients in whom no cause for DVT has been found. Missing a diagnosis of MTS could result in life-threatening conditions such as pulmonary embolism and post-thrombotic syndrome.