While it's true that a wet bed doesn't require microscopes to find the stain or smell, the fact that lab tests were performed doesn't necessarily mean the bed wasn't wet. I would guess that lab tests were necessary because simple human observation of the apparent state of a bedsheet wouldn't fly in a court of law.

Alternatively, the fact that the lab tests revealed evidence of urine doesn't necessarily prove that the bed had been wet THAT NIGHT. What we need are some more definitive answers.

Did the person(s) who removed the sheets notice the fresh odor of urine? I think this is important, because I would guess that over time, the odor would fade.

Was there an apparently unlaundered urine stain on the bed, visible to the naked eye?

Did the lab tests show only trace evidence of urine or was there a large amount? Surely there's a way to show the difference between finding trace evidence of urine from previous, pre-laundering bedwetting incidents and the overwhelming evidence from a sheet that had been through a bedwetting without being laundered.

I'm sure all these questions have been answered. However, the depo testimony above doesn't really provide those answers.