If it progressed to the point of a true medical emergency, I suspect the kit at least had the equipment necessary for a 'quick and dirty' suprapubic aspiration

If it progressed to the point of a true medical emergency, I suspect the kit at least had the equipment necessary for a 'quick and dirty' suprapubic aspiration of the bladder (stick a longish needle in from the front, and use a syringe to pull fluid out). Generally speaking, this is done with an ultrasound, but in a pinch, you could likely just palpate the bladder.