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If it is a basic procedure, they might be using a laser to remove nodes from the walls of your uterus. If they are doing an invasive surgery, it will be something equivalent to a mini-C-section if there are nodes on the outside of the walls of the uterus. But they should explain (or should've explained) that to you.
Also, Gender Reveal Parties have been going on for decades. It's just that with the blow-up of these parties on social media, it appears as if it's something that just started trending - regardless of how long it's been going on. However, the way the reveals are being done nowadays is going above and beyond the "pop-a-balloon" or "open a singing card" of old.
...and then there are the bloopers of "Reveals Gone Wrong"...