If, after the lab test your find that there is really urine in the drink, you may report it tot he police.
I've read a real court cases before, whereby the maid was proved to have added urine into the water of the meployer, and she was sent to jail finally cus she could not be able to explain why there was urine in the water (she gave the excuse that the little kid she took care had the habit of urinating anywhere inside the house, but he Judge did not accept this excuse). It you take action, you've got to do it timely(ASAP).