Locating drainage under cement

My first post, so please bare with me. Is there a good way to track the direction of a drain line running into the basement floor cement slab? I'm looking to add a bathroom 'not' where one was roughed in. I have clear visibility of the drain and vent lines going into the cement floor that are very close to where I would like to tap into. Hopefully it is as easy as knowing where the lines are and then cutting/jackhammering into the floor. Any advice would be greatly appreciated.

unless you can get some good dead reckoning for direction to look then all I can think of is if its PVC then run a metal cable in the pipe and use a pipe horn to locate it. For metal pipe you can use a pipe horn directly to transmit a locating signal. Personally, for local needs I just call the local gas company and the guys come out and run any line I want them to run....no problem.. for the most part I don't have a real need for locating equipment but there are locating services in some areas.... I'd love to own a pipe horn or other device to locate pipes. I've got a video camera I can run 100' in a 1 1/2" or larger pipe and get a good idea of where to dig.