sex before mid cycle ultrasound

Chelsie
Hey guys, 
My doc told me to BD CD12 the day before we go in to have our mid cycle ultrasound (today). I took an OPK yesterday and no surge...I was not feeling well and my husband was tired so we did not BD but we did on CD 10. Any reason why they would want us to specifically have sex that day? Will it reveal anything in the ultrasound? Do you think we're okay bc we didn't BD?