Common femoral vein wall thickness in antiphospholipid syndrome: a potential imaging biomarker

Venous wall thickness (VWT) has emerged as a marker of venous disease, and increased VWT as a possible indicator of vascular inflammation.

This study included patients aged ≥18 years who fulfilled the 2023 ACR/EULAR Classification Criteria for antiphospholipid syndrome (APS), along with age- and sex-matched healthy controls (HCs) and patients with chronic non-inflammatory deep vein thrombosis (DVT), enrolled between October 2024 and June 2025. Ultrasonographic measurements of bilateral common femoral vein (CFV) posterior wall thickness were performed at separate time points by two experienced radiologists blinded to clinical information, using a broadband linear probe.

A total of 55 APS patients, 28 HC, and 21 patients with chronic non-inflammatory DVT were included. The groups were comparable in terms of demographic and clinical characteristics. Among APS patients, 32 had venous thrombosis, 15 arterial thrombosis, 3 both venous and arterial thrombosis, and 5 had obstetric morbidity. Mean right and left CFV wall thicknesses were significantly higher in APS patients (right: 0.535 ± 0.058 mm; left: 0.529 ± 0.065 mm) compared with both chronic DVT patients (right: 0.405 ± 0.066 mm; left: 0.377 ± 0.039 mm) and HCs (right: 0.392 ± 0.043 mm; left: 0.388 ± 0.043 mm) (p<0.001 for both). No significant difference was observed between the chronic DVT and HC groups (p=1.0). Subgroup analysis demonstrated no significant differences in CFV wall thickness between APS patients with and without concomitant SLE. In addition, CFV wall thickness measurements did not differ according to aPL profile or prior venous thrombosis history. Receiver operating characteristic analysis identified optimal VWT cut-off values of 0.443 mm for the right CFV and 0.445 mm for the left CFV, both demonstrating high sensitivity and specificity (AUC >0.94, p<0.001).

In patients with uncertain APS diagnosis based on clinical manifestations and/or aPL positivity, measurement of VWT by ultrasonography may serve as a useful adjunctive tool in the diagnostic process.