I have no idea how the testing actually goes, how long the samples need to react with whatever or anything. If it's just a glance in the microscope, a mixing with testing fluid... no clue. So, how long is it? Immediate? A day? A week?
Also, what do they samples actually look like as the lab technician gets them? Does he get tubes with the substances in them, or are they already on a glass tray? How are they stored to keep them fresh? I assume the usual tests would be chlamydia (urethral swab or urine sample), gonorrhea (urethral swab) and HIV, Herpes and Hep B and C (blood samples). I just need some details so I can describe the scene properly.
I've googled and wikied STDs and testing, but most of the time I just got the timeframe info on HIV and most of them just go into great detail about incubation time, false negatives, necessary retesting etc. but that's not what I'm concerned about right now.