bloodtested

hey i got a little dilemma ok i had to get a blood test for a menongitis study at my pediatricians office. while i was getting my blood taken my mom jokingly said get him tested for drugs lol and the lady jokingly agreed i dunno if she was serious or not but it was kinda weird and i was wondering can she actually get it tested? or does it cost money? and if so i smoken 1/4 a blunt and 4 bowls 60 hours before do u think i would have passed if they actually tested it? i am 5'9 160 lbs any replies wouldd be great thx