Home – All FAQs – When is EVLA not required? When is EVLA not required? Home – All FAQs – When is EVLA not required? If the duplex ultrasound scan does not reveal any significant valve problems in your feeder veins, or if the veins are very small, EVLA treatment may not be required. If your veins are too small for the laser, the most likely alternative is foam sclerotherapy.