Fertilising eggs from the wrong sperm donor is a nightmare scenario for IVF clinics, which came to light in the case of a white woman in Leeds who found herself giving birth to black twins in 2002. But The Report's Nadene Ghouri has since found a routine neglect of safeguards to prevent such mix-ups at a major London hospital led one embryologist to turn whistle-blower.
Two witnesses should verify that the right sperm fertilised the right eggs
It was in January 2004 that clinical embryologist Bea Pavlovic, first became worried by errors in the patient notes she was checking at Guys Hospital, London.
Signatures were missing which should have stated which sperm had fertilised which egg and whether security checks had been performed.
Normally two people have to witness and check procedures - including that the right sperm has fertilised the right eggs - and sign documents to verify that at the time they carry out the procedure.
"I have no words to explain how important this is - it is paramount," she told The Report.
She added: "My first duty was to report this to my superiors."
Ms Pavlovic claims when she raised this verbally she was called a "broken record".
A year on she felt the concerns were not listened to and she photocopied patient records and took them home.
"I didn't feel very proud of having to do that but I knew without evidence I would not have anything there to prove," she said.
Eventually she wrote to the hospital's lead clinician and to IVF watchdog the Human Fertilisation and Embryology Authority.
Bea Pavlovic was sacked, lost her Employment Tribunal case and faced being struck off by her professional body when the hospital trust alleged she had potentially breached confidentiality by taking copies of patient notes home as evidence.
But she was not struck off, because although a Health Professional Council hearing in November 2008 agreed that she had risked breaching patient confidentiality, it also said she had "acted in the patients' best interests in doing so".
Bea said she felt vindicated by the decision and earlier this year it was revealed there had been a mix-up at Guys Hospital. In the case of two couples the wrong sperm was injected into the wrong eggs.
"I was very sad... there were mixed feelings, from shock, sadness, that I was right in everything I said."
Ms Pavlovic, who said she came across the errors by accident, added: "One has to ask how many are there that have not been picked up."
A statement from Guys and St Thomas's Hospital said: "We have already acted to minimise the risk of similar incidents happening again."
It added that the assisted conception unit has moved to a £4.2m state of the art new unit which provides added assurance that patient samples are handled correctly.
The trust has also introduced electronic tagging of samples.
But there are wider concerns over embryo mix-ups in IVF clinics.
Earlier this year Cardiff and Vale NHS Trust agreed to pay undisclosed damages to a couple whose last remaining embryo was wrongly given to another woman, after admitting there had been failures in care.
The couple's solicitor, Guy Forster, told The Report: "I have no doubt unless more is done these incidents will keep occurring... unless there's action from both the clinics and the HFEA then we're going to see some very serious mix-ups in the future."
His concerns were echoed by Professor Brian Toft, who investigated the 2002 Leeds mix-up for the HFEA.
Professor Toft said he was concerned that there would be further "disasters" unless the HFEA started applying sanctions to clinics which were ignoring safety guidelines.
After the Cardiff case he wrote to Health Secretary Andy Burnham.
"I have to say I am very disappointed because he didn't write (back) to me personally but had someone in the Customer Services Department do it," he said.
However Professor Lisa Jardine, chair of the HFEA, said there were dangers in implementing too strict a regime.
"In the rest of Europe and in America we're regarded as laughably tough.
"Now if we're not careful we will drive our patients abroad for treatment because our clinics are more severe and do not allow things that clinics abroad allow."
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