A nurse said she was furious her test for coronavirus was mislabelled meaning she would never know the result.
Maria Reid, 34, a deputy sister at Royal Cornwall Hospital, said the error meant she had been unable to see her children, potentially for no reason.
She said: “It is unacceptable, that level of incompetence should never have happened.”
The ambulance service that carried out the test said it was confident the problem would not happen again.
Ms Reid, from Fraddon in Cornwall, said she was told by work to self-isolate when she became symptomatic but the hospital did not offer to test her.
However, her husband, who she is separated from, works as an emergency care assistant for South Western Ambulance Service (SWAST) and when he told his employers about Ms Reid’s symptoms, they offered her a test.
She said: “I didn’t expect it so I was quite grateful at the time.”
Ms Reid, who works on the trauma unit at the hospital in Truro, was tested on 11 April and told the results usually took 24 to 48 hours to arrive.
After chasing the results, she was told on 18 April her sample had been mislabelled and she would never know the outcome.
“I am out of optimal testing time for a re-swab,” she said.
“It should be a basic thing for sampling to be labelled properly.
“It feels as if I have been done out of a result and I have been isolated potentially for no reason because it could have been negative.”
She said her experience made her “massively sceptical” about whether the government could achieve its target of getting 100,000 tests a day done by the end of the month.
Ms Reid said if her test had been negative she would have been able to see her children after seven days and she was told a negative result would have meant her husband – who had to isolate because of contact with her – could have gone back to work after seven days.
The lack of a result meant he instead had to isolate for 14 days and she was unable to see her children for the same period.
“The level of rage I feel is incomprehensible,” she said. “I have never ever gone 14 days without seeing my kids and this is all due to someone’s incompetence.”
A spokesman for SWAST said it had tested more than 250 people, “enabling the vast majority of staff tested to safely return to work when they feel able and well enough to do so”.
“We regret that in this instance we did not provide the service we would hope and have apologised to the individual involved,” he said.
“Furthermore we have modified our procedures and remain confident it will not happen again.”