I had one many years ago while in the military.
As I was set up for the procedure, I soon had empathy for women as I found myself in stirrups!
A technician numbed me up with a gel rubbed on my pubic area, . Luckily it was not a spinal. He commented “ Woukdn’t this be wonderful every morning before breakfast. !”’
Then the doctor came in and explained the procedure, and commenced, inserting the imaging probe into my urethra then into my bladder.
I had a condition ( microscopic hematuria) and they needed to check to assure I did not have bladder problems, viz: cancer. The procedure was soon over and the scope removed.
After the procedure the doctor said that as per my medical records despite having done three tours in Asia, I had no signs of a history of STDs, but the first time I passed urine after the procedure, I’d get an idea of what having the clap felt like! That proved true later that evening.
Long story made short. No issues found. But the microscopic hematuria sunk my military career. I had 8 years left to retirement and I was denied going back overseas . The reasons were based on $$$ not health. When my enlistment was up I got out, otherwise I would have done my final 8 “standing on my head” as one senior NCO told me. Wasn’t interested.