New Vein Compression Entities in Patients with Unexplained Leg Swelling.

Background: This retrospective study identifies often overlooked anatomical sites for nonthrombotic venous outflow obstruction (NTVO) in patients with unexplained lower extremity edema and pain.

Methods: We reviewed the charts of 75 consecutive patients experiencing symptoms of unexplained lower extremity edema with pain that were unexplained by ultrasound, computed tomography angiography (CTA), and magnetic resonance imaging (MRI), who subsequently underwent venography in an outpatient medical office from 2010 to 2014. We categorized venograms based on the presence or absence of NTVO lesions and calculated prevalence of each at specific sites.