How accurate is ultrasound for gender predication if done at 16 weeks and baby cooperates? gyn said 95 % boy. why not 100 % ig penis clear

Nothing is 100%: Your gyn was just being conservative and not wanting to say 100%, even if they believed conclusively that your fetus was male. What difference does it make anyway, as it's just an opinion, not a fact.

Predictions : It is very rare in medicine to make 100% diagnoses or predictions based upon testing, including radiology and ultrasound. It sure sounds like the gyn thinks you are having a boy. But nothing at this stage is 100% accurate 100% of the time.