Dark veins visible back of upper left thigh after sitting. i am thin active woman, 49yrs old. take provera, (medroxyprogesterone) do hot yoga. should i worry about clot?

No worry ..: If you are active although on Provera (medroxyprogesterone) but don't smoke yours veins are most likely superficial various veins which are more prominent when siting and fill up by gravity ! other veins - deep - which you don't see are the ones we worry if clot would form ! symptoms are usually pain in calf with walking, swelling, redness .. High risk is inactivity or genetic clothing problem. If any doubt- see md!

NO CLOT: If you can see the veins then they are superficial and are either spider veins which look like spider legs, varicose veins which tend to bulge or blue (reticular) veins which are the veins between spiders and vv. If they are not tender then they are not clotted and these veins do not form deep clots. You may want to see a vein specialist for a full vein evaluation.