I also take a urine sample, at the beginning of the exam, as part of my taking the patient's vitals. I've yet to have a patient refuse or decline it. I have a plastic vessel that's graduated inside in ml measurements. This vessel is designed to fit perfectly on the porcelain rim of the toilet, and it protrudes down. I do always tell my patients to arrive with a full bladder, but not uncomfortably so. I also inform them that I'll need to observe the flow into the plastic vessel , to determine the nature of the stream, i.e., sufficiently fast, or slow.
So that I can better determine any abnormalities of the urine flow, I do feel and hold the patient's penis during his urination. None has ever objected. If his penis has become erect and he can't pee, I simply wait until later.
When he's finished, I check the urine's quantity. If the patient states that he arrived with a pretty full bladder, the quantity seems to average about 400 ml. I then check for color and clarity, as I tell the patient, "just like a fine diamond." That always gets a laugh. I also keep a set of diabetic strips, one of which I drop into the urine. You're looking for a color change, which will determine the presence of sugar.
After that, I have a 2-liter bottle of water that I have the patient drink as much as he can. Later in the exam, usually during the genital exam portion, I'll do another urine check. Except this time, it's as the patient relaxes on the table wherein I insert a catheter to obtain the urine flow. I allow the urine to flow into the same vessel as mentioned above, which has been placed adjacent to the patient. Many are surprised at the sudden, involuntary onset of their urination, once the catheter passes by their prostate and into the bladder.