We had a similar issue in Burkina Faso. My husband has dreadlocks, so they immediately targeted him for a drug test, no one else in his group got one. He smokes weed, and thought it wasn't a big deal seeing as though where he would be immigrating to, it's legal. Anyway, the dr was kind enough to not send the positive result into the embassy with the rest of the medicals, but made him keep retesting over and over (mind you it's $50 every time) until he came back negative. Took 90 days. Idk what test they're using but I've never seen such a thing, I work in medicine. Finally they sent over the medicals just a few days ago, but we're in administrative processing now until Oct 23rd. Fun times. Seriously though, no complaints, if we would have done the interview in Ghana, we would still be waiting for another year! So, it's whatever.