Home – All FAQs – Why would I have EVLA over foam sclerotherapy? Why would I have EVLA over foam sclerotherapy? Home – All FAQs – Why would I have EVLA over foam sclerotherapy? The foam is cheaper but not nearly as effective as laser in the majority of patients. It is only suitable as the primary treatment for a small minority of patients. A duplex ultrasound scan will be necessary to determine who may be suitable for treatment just by foam and who needs laser. The success rate of treating the underlying cause with foam sclerotherapy is low and hence such a strategy is not one we adopt at Veincentre.