Assuming this question is about spider veins on the legs, if the vessels blanch (go away) when you push on them, then the vessels are still open and carrying blood and are not fully treated. If the treatment was 10 days ago, then you can assume you'll need more treatments. This can occur if the treatment is not appropriate for the vessel in size or color, if the underlying feeder veins were not addressed, or if not enough energy was used to treat the vessel.
Unless the spider veins on the legs are tiny and red, then PDL is not usually the first choice for treatment. Sclerotherapy with polidocanol (POL) or sodium tetrodecyl sulfate (STS) is still considered the gold standard for spider vein treatments on the legs. Alternatively 532 KTP or 1064 NdYag lasers are generally thought to be more efficacious for laser treatments of spider veins of the legs.
It is important to have an ultrasound of the legs before any treatment of spider veins is started. This is to be sure the underlying venous network is functioning properly to allow any spider vein treatment to proceed successfully. If the underlying veins are not functioning properly underneath the spider veins, then the chances of treatment success is greatly reduced.