I had a sepsis incident a couple of years ago which NHS online, out-of-hours GP clinic, & ambulance staff failed to diagnose. I was in Intensive Care ward with vital signs dropping before (after X-rays, scans and blood tests) it was diagnosed correctly and iv antibiotics administered. My subsequent blood tests continued to raise concern and it took another scan in another hospital to spot the real cause: basically overlarge prostate blocking tube from kidneys. Surgery solved it. My wife observed Casualty staff trying test after test and consulting several specialists before they nailed it. I'm 100 percent OK now but it was touch and go.
Rts