Everytime I use a sound into my blatter I get a UTI
I keep them now from going tooo deep
You always take some risk of a UTI when you penetrate the bladder muscle, and go into the bladder, whether with a sound or a catheter.
Two things, first make sure you use sterile lube, and a sterile sound or catheter. Also make sure you wash the head of your penis, as well as your hands.
Or, just stop short of entering the bladder.
There are many men out there that 'have to' use a catheter to drain their bladders, and they don't have this problem because they follow proper procedures.
Some years ago after a back injury, I was in a different, but similar situation. Not needing to drain my bladder, but dilate the urethra because of constrictions. My doctor set me up with an appointment with a nurse to teach me how to 'self cath'. She was the one that told me about the number of men that have to do this several times a day.
Was surprised when the first thing she had done was to open the insertion tray kit, and throw away the sterile drapes, cotton balls, plastic tweezers, and iodine. Had asked didn't I need all that? Answer was no...
Was explained to me that my body can handle my own germs, but not anyone else's. Just to keep the catheter washed and cleaned, wash my hands, the head of my penis, use sterile lube, and wouldn't have any problems. And I never did.
Didn't really need to drain my bladder just dilate the urethra, so really didn't need to take it all the way into the bladder, but did often anyway. There's a erotic, pleasant feeling when something penetrates that bladder muscle, that can get as addicting as a good prostate massage.