obtaining a urine sample

Urine sample from a tiny one? I've heard of using a soaked diaper, but never patiently waiting with a cup.

If it is necessary in a hospital setting they insert a catheter.

When my daughter was very tiny, there was some situation (I forget what it was) where we needed a urine sample, and they gave us this contraption to collect it. It was just a little plastic bag that had sticky stuff on some sort of a foam oval that we were supposed to just stick right on her, and leave under the diapers. It was weird, but it worked.

That didn't seem to worry about mid-stream or anything.

One would think that if a urine sample was required, there would also be someone medical who requested it and can give advice on how to get it, though.

Fortunately I've never been in this situation. Would it be possible to clean/disinfect and then rinse the potty thoroughly before use, encourage your daughter to go (or wait until she is ready, depending on the situation) and pour a little into the cup (using a funnel or over the toilet). It's probably a bit messy, but if a soaked nappy doesn't contaminate the sample, a clean potty is unlikely to.

Anyway, your doctor should be able to give you an idea about how it is usually done.