Anatomy scan question. (20 week ultrasound)

Shanaye • Sienna 💞 29/10/2016 👶🏼 Titan 💙 18/05/2019 👶🏼
My scan is in about an hour, and I haven't been told anything as in do I need an empty bladder, semi full bladder or a full bladder ? I really don't know. Most ultrasounds I've been told to drink like 600mls of water but have been told nothing for this scan. Help! Lol