The number of mistakes or near-misses in IVF treatment has more than trebled in three years, figures have revealed.

Errors that include the loss of patients’ embryos and sperm rose to 564 between April 2010 and March 2011, up from 182 between April 2007 and March 2008, the Human Fertilisation and Embryology Authority said.

The figures, released after a Freedom of Information request by Irwin Mitchell solicitors, showed that the number of Category A incidents, described as those with major or serious consequences for patients, embryo, gamete or staff safety and service quality, fell from eight to one in the same period.

Between April 2005 and March 2006 the number of incidents classed as Category A was 91.

Guy Forster, a solicitor with Irwin Mitchell, which specialises in medical negligence cases involving IVF incidents, said a change in the way the regulator categorises these incidents means there could be inconsistency or a lack of effectiveness in the way it responds to them, with offending clinics often escaping inspection or any sanctions by the regulator.

Mr Forster said: “Since 2008, incidents as a whole have more than trebled.

“Although it should be recognised that 564 incidents represents a small proportion of the 50,000 IVF cycles carried out in the UK each year, when things do go wrong, it causes the most unimaginable heartache for those involved and it is vital that both the clinic in question and the IVF industry as a whole learn lessons for the future.

“The HFEA is in the unique position of being able to share these lessons with other UK clinics but, in the last two years, has only issued three alerts.

“When patients choose to undergo IVF treatment they have the right to know if their clinic has a poor record of incidents, in the same way that clinics are keen to promote their success rates.

“At the same time, they deserve to know that the HFEA will act to uphold patient safety standards across the industry.

“Sadly, the HFEA which as the official regulator exists both to police the industry and ensure best practice, is not transparent in the way it reports incidents. Since 2003, the regulator has in effect moved the goalposts by changing the way it categorises the seriousness of errors.

“Whilst the data reveals that the number of incidents overall has trebled, according to the HFEA the number of most serious “grade A” incidents has dramatically fallen from 91 in 2006 to just one in 2010-11. This not only calls into question whether incidents are being routinely downgraded, but also means that the inspections, which would automatically have been triggered by a grade A incident, are no longer taking place.

“The HFEA’s figures may indicate that grade A incidents have fallen but, when added together with grade B incidents, the two most serious categories have in fact more than quadrupled over the past three years. However you look at it, the statistics are deeply concerning.”

Mr Forster continued: “Following the government’s announcement that it intends to abolish quangos such as the HFEA, the responsibility for regulating the fertility sector will pass to the Care Quality Commission.

“When the time comes, we hope the CQC will seize the opportunity to improve the way in which the HFEA has been regulating the sector.”

The solicitor has successfully represented a number of couples whose IVF treatment failed after clinical errors, including one couple whose last remaining embryo was wrongly implanted into another patient.

When the mistake, which happened in December 2007, was discovered, the patient took the morning-after pill.

Cardiff and Vale University Health Board, who are responsible for IVF Wales, admitted liability for gross failures in care resulting from the incident and, in June 2009, paid out an undisclosed five-figure sum in compensation to the couple.

An HFEA spokesman said: “The HFEA openly encourages the reporting of incidents and continues to work closely with centres to improve quality.

“As a result, centres are continuing to respond positively to the opportunity to share lessons learned from incidents which have been reviewed and vigorously investigated.

“There has actually been a fall in the number of the most serious incidents. In the last year there were more than 50,000 cycles of IVF which entails hundreds of thousands of laboratory procedures.

“The HFEA takes all incidents seriously but the total number of incidents represents a tiny percentage of all the procedures taking place.”