Fluid buildup in bladder during masturbation?

When I'm masturbating, I like to edge a lot. Sometimes, especially if I'm at it for a while, fluid starts to build up in my bladder and I have to use the restroom. I know this is actually happening, and not just a feeling, since I will physically get up and go use the toilet. I let loose a pretty large amount of clear urine even if I already went before starting my masturbation session.

I'm not sure what it is, exactly, since I never drink so much water that my urine isn't yellow, and I'm not in the habit of drinking tons of water shortly before masturbating. Trying to Google this comes up with results that deal entirely with women squirting, which has nothing to do with me because I'M NOT FEMALE. I'm not trans, I didn't change my "identity", I don't have an extra chromosome, I'm a regular man.

Trying to take girls out of the search leaves me with results about prostatitis. I'm sure it's not that, since I don't have a single one of the symptoms of prostatitis. I have no pain anywhere, no difficulty urinating, and no sudden urgency. I'm pretty sure it's not retrograde ejaculation, since I do still expel semen during and after my session.

So, what could this be? Has this happened to any other dudes?