I can't remember which insurance company we used, but a few years ago my wife was taken ill on board with some sort of bacterial or viral infection. At first, we didn't think it was too serious and we ran up a small medical bill. To be honest, I would have paid this and not bothered with an insurance claim. However after three days, the medical team were getting concerned and advised me that they would send my wife to hospital at the next port. Basically they said to me, "Go and pack your bags in readiness to leave the ship next day" At this point I thought I had better telephone the insurance company. When I called them, they 'reprimanded' me for not calling them as soon as my wife was taken ill. They advised me that if we had to disembark, they, the insurance company would decide which hospital and doctors we would use.
Fortunately my wife improved next day and they allowed us to stay on ship. We ran up a medical bill of around £1500 GBP. When we arrived home, we completed and sent off a claim form. The expenses were paid in full within a week.
The moral of my story is, if you feel that anyone needs medical attention, always call the insurance company at your first opportunity.
When I think back about this, I'm surprised that the medical team didn't call the insurance company before they began treatment, as the cruise line has details of all passengers insurance.