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Electronic tags for eggs, sperm and embryos
IN 2002, two proud and relieved parents, Mr and Mrs A, saw their newborn twins for the first time, conceived after a long and difficult course of IVF treatment. At last it all seemed worthwhile. Except the babies were of mixed race, while both parents were white.
The IVF clinic had blundered, and used the wrong sperm to fertilise Mrs A's eggs. The child's biological father was Mr B, a man the couple had never met and who with his partner was also trying for a family using IVF. Similar accidents have happened in the US and the Netherlands.
Now, in a bid to stop such mistakes happening again, the UK's regulatory body, the Human Fertilisation and Embryology Authority (HFEA) is considering labelling all embryos, eggs and sperm with barcodes or electronic ID tags. The idea, discussed at the HFEA's annual conference in London last month, is that an alarm will sound if the wrong eggs and sperm are brought close to one another, for instance, or if a doctor attempts to collect the wrong embryo to implant into a mother-to-be.
In June 2004, an independent report commissioned by the UK's chief medical officer suggested clinics use a system of double-witnessing, which requires an embryologist to ask a colleague to witness and document every procedure in which an error could occur. But with 25 such procedures required for each round of IVF, the system is laborious. And it still leaves room for human error.
Steve Troup, an embryologist on the HFEA's advisory group on safety and new technologies, is looking into alternatives. Barcoding has been used for more than a decade in the UK's blood transfusion service, where it has slashed the error rate. Now IMT International, in Chester, UK, is developing barcodes for IVF procedures. Digital cameras built into the IVF clinic's benches read the barcodes off the bottom of labelled dishes containing eggs. A computer then reads the codes, and sounds an alarm if they do not match with the patient. "Our system is incredibly safe," says Tim Haywood, director of IMT International.
The electronic tags, known as RFID tags, work in a similar way. They can be placed on the bottom of a dish containing an embryo, and are activated by radio waves which transmit across a clinic's designated work areas. When activated, RFID tags respond by transmitting a unique ID code. "If the samples don't match [the patient], or you bring together two things that shouldn't be in the same work area, the alarms will sound," Troup says.The HFEA is investigating whether such a system would be safe, as there are concerns that radio waves might harm embryos. IVF Witness, an RFID system being developed by Research Instruments, in Falmouth, UK, has been tested on mouse embryos. The embryos are placed in Petri dishes which have tags attached to the bottom, and placed in an incubator with an antenna that activates the tags. In Research Instruments' tests, the tags transmitted continuously for four days without any perceptible effect on the embryos. Though the tests are not complete, "it looks very, very good that there's going to be no problem with it," David Lansdowne, technical director at the company told New Scientist.
Troup's personal view is that RFID tags will be safe for in vitro procedures. The tags only transmit when activated by an external signal. And they work at the low frequency of 13.5 megahertz compared with 900 to 1900 megahertz used by cellphones.
The advisory group will need to be satisfied that such an RFID system would not significantly heat up an embryo, or cause other as-yet-unknown problems. Troup's research team at the University of Liverpool, together with researchers at the University of Manchester, will be carrying out more work looking at the effect of radio waves on mouse embryos. Lansdowne says his team will be measuring the field strength from the RFID tags when the embryos are being worked on, and comparing this with background levels of radio waves.