baby has ranula?

Kelly • I'm a teen mother to a beautiful Mexican-Vietnamese baby. 👑
Hey Mommas. I recently found a little bubble like molecule at the floor of my daughters tongue and I don't know how to deal with this right now. Her pediatrician told us that it's called ranula and she referred us to a ENT doctor. Supposely she will be getting surgery to take it out so they can run some tests but I'm just so worried. WThis will be her 2nd surgery and she's not even one year old yet. 
(First surgery was for tubes for her ear infection.) 
Do any of you know or have babies that have had ranula? Is it really ranula? Is it life threatening?... 
Here's a picture of what it looks like. (Had to tease her with puffs)