Furthermore, some patients have both and there are two different valves/tubes. How do you know which one is which?
My hospital uses different insertion catheter connectors for G and GJ. We are in the process of converting to a GJ that looks more like our G tube (the Mickey button). The new GJ has two hook up holes instead of just one, and each hole is clearly labled G or J. If you are ever in doubt, I would look in the pt's H&P.
A GJ will have 2 clearly labeled ports, while the G will have one port.
Don't feel ashamed to ask the patient. It is nothing to be embarrassed of and you can learn a lot about why a patient has something or other helpful information not found in the chart just by asking.
A GJ will have two ports as well as the port for the balloon. Each port should be labeled clearly, though in small text. GOMER42 has some good advice, don't be afraid to ask the patient, they probably know their tubes best of all!