I'm sorry that you've been struggling with these urinary issues! That certainly sounds like a drag, for sure. I hope that you can get some answers soon and hopefully also something that changes this for you. It's so stressful to deal with bladder or bowel urgency issues.
I do want to say that it is always okay as a patient for us to ask however many questions, and whatever questions, we have of healthcare providers, very much including questions like if a given text is safe, why they're doing it, and if there's anything that might happen with a test we should know about ahead of time. I'd encourage you to ask these questions of your doctors, nurses or other clinicians, as they're going to know best.
I think the information Johns Hopkins gives about these tests on their website might be helpful to you: https://www.hopkinsmedicine.org/health/ ... l-sonogram
. I'm not an expert about this kind of ultrasound, and they are.
I don't think there's any cause for concern about fluids being released from the penis, though: it's unlikely that would happen from this test.
But do know that anyone doing these kinds of healthcare where they are having something to do with people's genitals -- things like this, things like testicular manual exams or GYN exams, etc. -- are used to genitals having all of the various kinds of responses that genitals can to direct or indirect stimulation, like erections (of the penis, of the clitoris), like fluids showing up, increasing or decreasing, like sounds our bodies can make. If and when things do happen, they are usually expecting them, don't think any of of them, and we're never the first person they've likely seem a thing happen with.