Earlier quoted context omitted.
The stricken passenger had the option of using the restroom, but for unknown reasons could not urinate. They stretched him out on a row of seats which seemed to help the pain, but from what I recall was unable to go until they reached the destination airport. The total trip time was about three hours.
Huh. According to the article that you linked to about the coat hanger, brandy, and rubber tube: 'The aircraft's medical kit is "quite well-equipped for having babies and people who develop urinary blockages..."'. In fact, it sounds like the tube they used to drain the lung was a catheter intended for urinary blockage. I wonder why they couldn't use such a catheter for this guy; did that kit not have one?
Generally speaking, this is done with an ultrasound, but in a pinch, you could likely just palpate the bladder.