I've not had an appointment rescheduled while I was on the way there, I've had the opposite - an appointment newly scheduled when I was miles away.
A few years ago my lower left leg swelled up painfully. The GP said he was pretty sure it was phlebitis, here's a prescription for an antibiotic, but I need to do a blood test to make sure it's not a deep vein thrombosis. OK I said, but we're going away to south Wales tomorrow. We were almost there (on the M4 passing Newport for those who know the area) when my phone rang. It was my GP surgery - your test results are a bit high, can you come here straight away. No, I'm in south Wales. OK, I'll have a word with doctor....... right you need to go to the nearest A & E department and tell them the results of this test are this.
We got to the hotel in Cardiff and asked where the nearest A & E was, we were pretty sure where as we were at Cardiff University in the 1970s and yes, it was still at the same hospital. We spent the next 5 hours there. They tried to do a repeat blood test but the lab was having computer problems, so they phoned my GP for yesterday's results, catching them just before they closed for the day. By this time it was too late to have a dopler scan so they injected an anticoagulant and sent me out. Next morning over breakfast the hospital rang and said to go in half an hour for the scan.
That showed I did not have a deep vein thrombosis, just phlebitis. I suppose the GP would have been negligent if he hadn't done the test and sent me to A & E in Cardiff, but it did feel like a waste of time. And I spent my brother-in-law's wedding anniversary party sitting with my leg raised on a second chair. At least it got me out of dancing - my brother-in-law plays the fiddle for a Morris dancing troupe, and they got everyone except me trying to dance with them