How accurate is ultrasound at 16 weeks pregnancy for gender detection if baby cooperate. is it 80% or 85% or 95%. based on experience and medical papers?

Depends on fetus: 16 weeks is quite early, and there is never a guarantee. If the fetus spreads it's legs and is in the right position for the us technologist, it can be very easy to tell the gender. If the fetus does not cooperate, then the accuracy goes down, to just guessing or flipping a coin (50%). It is easier to tell at 20 weeks or so (everything is bigger). Ask the tech how confident they are.