30 week sonogram

Have my 30 week sonogram and dr appt tomorrow. Anything that I should expect for this? Do they just take more measurements or is there anything else specific they are looking at at this point? Not sure what other questions/discussions I should be bringing up with my Dr as we get closer to delivery. My appointments have been very brief and typically they just ask me what questions I have, rather than filling me in on certain things that I should be aware of or thinking about at this time. Last time I even had to remind them that I was supposed to be getting the rH shot that was needed. 😕