I deal with this issue also.

I have found that doctor's are reluctant to put one in simply for ease of access in general. When I did a once a month IVig for several months they put one in, but once the therapy is complete they wouldn't leave it in because infection can set in and cause more problems. I was begging to keep it in because I have no veins anywhere (no arms, no hands, no feet). You can try any of the tricks (drink lots of water before hand, use a blood pressure cuff instead of rubber, turn lights out and look with a flashlight, put a warm rag on, and nothing helps)

Something I have discovered within the last year: Some places can use a handheld sonogram to look for veins deep in the arm. I have found a hospital that has one and I go there for all my bloodwork now. It is great. After 10 years of being tortured, they now hit the vein on the first try.

Another suggestion: If you have to go into the hospital for an IV, ask for either neo natal or life flight. They are the best of the best at getting veins.