Will I need to stop HRT for menopausal symptoms prior to having sclerothapy for spider/varicose veins?

It’s important to distinguish between varicose veins and spider veins when choosing between laser therapy, sclerotherapy, and vein surgery. With two board certified vein specialists, our center uses a combination of visual examination, functional flow measurements, ultrasound, transillumination, and infrared light to map out vein networks prior to therapy. Lasers can be used to treat deep varicose vein insufficiency, vein perforators, and varicose veins. Sclerotherapy is ideal for spider veins and reticular veins. Whereas surgery is reserved for severely incompetent varicose vein segments. 
Dr. Karamanoukian
Realself100 Surgeon

There is generally no need to discontinue or change your HRT therapy before or after routine sclerotherapy or spider veins. 
If you are having a more involved procedure like saphenous vein ablation then your surgeon may wish you to discontinue HRT in the period immediately before and after the procedure. Unfortunately there is not much reliable data on this situation though many surgeons and patients "would rather be safe than sorry".

I do not advise my patients to stop HRT prior to or after sclerotherapy.  We have not had any issues with patients on these medications.  Discuss this with your provider who can best advise you.