The aim of this study was to evaluate whether foam sclerotherapy (FS) induces changes in CAT (calibrated automated thrombinography) and other coagulation parameters which could indicate an increased risk of thrombotic events.

Blood samples from eight patients treated with FS were taken before treatment and 30 minutes, one and four hours and one week after treatment. CAT parameters (ETP1n, Peak1n, Lag time 1), thrombin antithrombin complexes (TAT), d-dimers, fibrinogen, Von Willebrand (vWf Ag) factor and platelet-derived microparticles (MIPAs) were measured.

Significant changes over time for Peak1n, fibrinogen, d-dimers, vWfAg and TAT complexes were observed. CAT parameters decreased over time, except for Lag time 1. D-dimers and TAT complexes increased and fibrinogen, vWf Ag, MIPA's decreased during the first hours.

The findings in this study support the hypothesis that FS initiate coagulation pathways, but there is no evidence that this activation results in an increased thrombosis risk.