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Laboratory Follow Up

31 August 2005

Laboratory Follow Up

Follow up by the National Screening Unit on all laboratories contracted with the programme has identified a further 16 women now being recalled for rescreening due to a laboratory processing error the Health Ministry confirmed today.

These 16 women from the Canterbury region are being contacted by their general practitioners to arrange for a repeat smear at no cost to the women.

The error affecting these 16 women is the same as the error affecting 37 Tairawhiti women where an incorrect method was used to process smears collected using a new product and which may result in the smear results being unreliable.

Hazel Lewis, Clinical Leader of the National Cervical Screening Programme, says that for most of the women involved, the error occurred recently but for a small number the error occurred up to 17 months ago. However advice received by the Ministry remains that the risk for women is very small. Both the Ministry and the laboratories concerned appreciate the inconvenience caused to affected women.

Dr Lewis says the Ministry's focus remains on ensuring the error does not occur again and women are followed up appropriately.

International Accreditation New Zealand (IANZ) is working with the NSU and both laboratories concerned to investigate the error and subsequent corrective actions.

IANZ is satisfied with the initial investigation by one laboratory and will be following up with both laboratories to ensure correct processes are in place.

The NSU and IANZ will also be monitoring all laboratories providing this service for appropriate compliance with agreed standards and manufacturers' instructions.

The NSU has also written to all laboratories contracted to provide cytology screening services asking them to review their collection and processing procedures, particularly in relation to the use of new products.

A woman?s best protection against developing cervical cancer is having regular cervical smear tests. The National Cervical Screening Programme recommends cervical smear tests every three years for women from the age of 20 until they turn 70.

Any woman with concerns is encouraged to contact her doctor or smear taker.

For more information contact: Peter Abernethy Communications Manager ph: 04-496-2008 or 021-366-111

Other contacts: Southern Community Laboratories, Director, Dr Peter Fitzgerald, ph: 07-340-783 or 021-104-9446 Medlab South, Histopathologist, Dr Shona McDowell, 03-363-0824 Canterbury Health Laboratories, Pf Peter George, 021-709-650

Background Information How many women were affected? Cervical samples from 37 women from Tairawhiti and 16 from Canterbury have been affected. All women have been or will be rescreened.

How do we know that all women have been identified? Southern Community Laboratory pathologists have conducted a thorough audit of electronic and paper records to ensure that all women who may have had their smears processed incorrectly have been identified. Medlab South staff have identified four samples were mistakenly processed when SurePath was first introduced 17 months ago. The four women had a conventional smear taken at the same time and do not need to be recalled.

Who pays for the repeat smear? The cost of the repeat smears will be met by Southern Community Laboratories.

What is to stop this happening in other regions? SurePath technology is only used by Canterbury Health Laboratories in New Zealand. The National Cervical Screening Programme (NCSP) has written to all other cytology contracted labs advising them of this error asking them to review their processes. Further technical information has been provided for laboratories by the SurePath company.

What was the technical fault? The smear samples (of cells taken from a woman's cervix) were collected using equipment and solutions provided by one manufacturer (SurePath) and then processed by using a different manufacturer's products (ThinPrep). Although the technology used by the two firms are similar, both manufacturers advise against doing this. Once the error was recognised, the samples were traced and medical practices and women alerted to what had happened.

What are SurePath and ThinPrep? They are two commercial methods for preparing cervical smears using a liquid based technology. The traditional method of smear preparation to screen for cervical cancer is the Pap smear where a sample of cells from an individual's cervix is collected, spread thinly on a glass slide, stained and then examined under a microscope for unusual cells. Liquid based cytology involves taking a similar sample, mixing that in liquid and then processing in a machine to provide sample cervical cells on a glass slide to be examined under a microscope.

What is the difference between SurePath and Thin Prep? The two liquid based technologies used in NZ, ThinPrep and SurePath, use different fixatives in their collection vials. The validation studies performed on each system are based on specimens processed only with the appropriate fixative solutions. The manufacturers recommend that the collection vials and processing systems are not able to be mixed and results obtained from processing specimens in this way have not been validated and may be unreliable.

How common is liquid based cytology in New Zealand? Based on a survey by the NCSP done late last year, the NSU estimates that approximately a third of all cervical screening slides are examined using liquid based cytology.

What does the Ministry advise where the processes have been mixed by error? The Ministry believes that the steps being taken by the laboratories involved are appropriate, that is to invite those individuals whose samples were processed through a combination of SurePath and Thin Prep, to be rescreened.

What does rescreening involve? The individual women will be invited to have another cervical smear taken and have those processed and examined.

What risks are the individual women exposed to? The individual risk for women concerned is regarded as very small. Each of the 53 women are being screened as part of the standard screening process.

How was the Ministry alerted to the problem? A Southern Community Laboratory staff member discussed the interchangability of the two processes with a representative of the manufacturer. The manufacturer pointed out the two processes were not identical and results using a combined process may not be reliable. The manufacturer alerted Canterbury Health Laboratories (which is the only laboratory using SurePath) and Canterbury Health Laboratories alerted the Ministry. Since then Ministry checks with other laboratories has revealed another laboratory, Medlab South, as having four samples where a similar error occurred. The four women had a conventional smear taken at the same time and do not need to be recalled.

Shouldn't this have been picked up by other processes? The issue was effectively detected through the professionalism of staff involved. There are appropriate standards (and quality assurance processes) in place for laboratories regarding the introduction and use of any new products through IANZ accreditation and surveillance.

What processes are in place to prevent this happening again? The National Cervical Screening Programme has Operational Policy and Quality Standards for medical laboratories. In the Agreement with medical laboratories contracted by the National Screening Unit to provide cytology screening services, all medical laboratories are required to meet the relevant standards and be internationally accredited by IANZ. As part of that accreditation there is annual surveillance of the laboratory's performance and a three yearly audit. The NSU also audits each laboratory on a three yearly cycle. Six laboratories were audited by the NSU in the last financial year and the remaining four will be audited this year. There are a range of other standards and auditing processes for other parts of the screening pathway.

Does the NCSP have standards for Liquid Based Cytology? The NCSP is currently reviewing all cytology laboratory standards. The review includes consideration of international and best practice guidelines for laboratories. LBC specific standards will be included and implemented by 1 July 2006

What does IANZ stand for? International Accreditation New Zealand. Accreditation is the recognition by an official accreditation body of appropriate standards. IANZ is the operational arm of the Testing Laboratory Registration Council (TELARC). IANZ is a non-profit and user-funded body. It is a New Zealand Crown entity reporting annually to Parliament and established by the Testing Laboratory Registration Act 1972.


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