What to drink before gender ultrasound?

Water, if needed. Some physicians want to do imaging when patients have a full bladder; others don't have a preference. Visualizing genitalia depends on the us type done (vaginal vs abdominal), gestational age, fetal position and gender (boys>girls tend to give away the 'secret'). It is best to call the office to ask what the sonographer or doctor prefers before filling the bladder and making oneself uncomfortable.