Evaluation of the minimum effective concentration of foam sclerosant in an ex-vivo study.

Foam sclerosants are widely used in sclerotherapy and have been accepted as more effective than the liquid form; however, there is no consensus about the most applicable and effective concentration. The aim of this study was to investigate the histopathological changes caused by various widely used concentrations of foam sclerosant. Fifty-six varicose vein segments of 5-10 mm diameter were gently resected and exposed to various concentrations of foam sclerosant (0.5%, 1%, 2%, 3%) for 5 min, and were then prepared for routine histopathological examination. A total damage scoring system, including the presence of endothelial swelling, intimal thickening, cellular vacuolization in the muscle layer, edema in the tunica media and extent of necrosis, was established. The total damage score of the foam sclerosant groups was significantly higher than that of the control group (median 2.75 vs 1, p = 0.007). The highest damage score was achieved by 1% and 2% foam sclerosants (3.5 and 2.5). No significant difference was found among the different concentrations of sclerosant, although the 1% group caused more severe damage at a near significant level (p = 0.074). Significant pathological damage can be caused by even the lowest doses of foam sclerosant. The most injurious concentrations were found to be 1% and 2%, morphologically. A working concentration of 1% could thus be preferable to 0.5%, especially in larger veins. Further in-vivo studies are needed in order to validate these findings.