Pathogenesis and etiology of recurrent varicose veins.

Background: Recurrent varicose veins (RVV) occur in 13% to 65% of patients following treatment, and remain a debilitating and costly problem. RVV were initially thought largely to be due to inadequate intervention, however, more recently neovascularization and other factors have been implicated. This review aims to provide an overview of the current understanding of the etiology and pathogenesis of RVV.

Methods: A systematic search of the PubMed database was performed using the search terms including "recurrent," "varicose veins," and "neovascularization."

Results: Three types of RVV have been reported, namely residual veins, true RVV, and new varicose veins, although the definitions varied between studies. RVV are attributable to causes including inadequate treatment, disease progression, and neovascularization. Using duplex ultrasonography, neovascularization has been observed in 25% to 94% of RVV. These new vessels appear in various size, number, and tortuosity, and they reconnect previously treated diseased veins to the lower limb venous circulation. Histologically, these vessels appear primitive with incomplete vein wall formation, decreased elastic component, and lack of valves and accompanying nerves. Although the rate of RVV following open surgery and endovenous treatment appears similar, neovascularization seems less common following endothermal ablation. Other causes of RVV following endovenous treatment include recanalization and opening of collaterals.

Conclusions: Recurrence remains poorly understood following treatment of varicose veins. Neovascularization is an established and common cause of RVV, although other factors may contribute.