Sticking a catheter into the bladder is a dangerous business - it carries bugs with it that can be very hard to eradicate. See title link for the general state of alarm.
30 years ago Dr Reese Alsop at the Huntingdon Hospital, NY wrote up a method for avoiding these risks. He played the patients a tape of water sounds!
In summary, he wrote: "A 30 minute tape of splashing, gurgling, lapping, running, roaring, dripping and flushing watery sounds was made available to post-operative patients who were still unable to pee following conventional non-invasive treatment. 60 of 80 patients responded, often requiring 20+ minutes to do so - but that's 75% of catheterisation avoided.". He concluded: "A word of warning: earphones are de rigeur. On several occasions the tape was inadvertently broadcast, with unfortunate results for other patients and nursing staff."
Obvious when you think of it - it's one of our most ingrained responses. Has it been taken up - or even tried again - by the medical profession? Fat chance.