New probe could provide on-the-spot indentification of abnormal cells

Consultant Gynaecologist, John Tidy, with the cervical probe

Sheffield Teaching Hospitals NHS Foundation Trust has developed a unique medical probe that could provide a much faster method of diagnosing pre-cancerous cells in the cervix than the traditional “smear test”.

Studies using an electrical impedance probe indicate that early tissue cell abnormalities can be immediately identified, effectively meaning that women could be sent for further investigation and treatment much more quickly.

Cervical cancer affects around 9 in every 100,000 women and 2400 cases are diagnosed every year in the UK. The exact cause of the disease is unknown although certain types of human papillomavirus (HPV) are linked with around 95 percent of cases and may be passed on through sex.

Abnormal cells found at the end of the cervix are called cervical intraepithelial neoplasia (CIN) and are detected by a smear test. CIN develops slowly over many years and if cells are identified early they can be treated and the development of cervical cancer prevented.

Presently, cervical smear testing involves doctors sending off samples for analysis in medical laboratories, a process that can leave women facing an anxious wait of four to five weeks for their results. Smear testing is not always accurate and works on the principle that women are entered into a programme where regular testing will ensure that CIN is detected.

The new probe, which was developed by the Trust’s medical physics team in conjunction with consultants from obstetrics and gynaecology, can be used to accurately identify these CIN cells during an examination, giving doctors a clear indication of whether a woman will need to undergo further tests.

In tissue cells, low frequency electrical currents travel around cells and can inform doctors of cell shapes and how they are arranged. High frequency currents flow through cells and can show up any changes to the internal cell structure including the cell nucleus.

Results from previous studies show that in CIN cells the nuclei increase in size, space between cells increases and there is a loss of cell layering. The readings from the probe measure these changes and can therefore determine whether the cells have become pre-cancerous.

Consultant Gynaecologist, Mr John Tidy, has been leading the study:

“ Our aim was to develop a method of diagnosis that could potentially replace cervical smear testing and provide doctors with accurate, on-the-spot results. This will cut the time between diagnosis and treatment and avoid causing women to worry, often unnecessarily, whilst they wait for results.

“The introduction of a probe instead of smear testing may prove beneficial in the future as it will reduce the costs of the national screening programme. We are also facing a national shortage of the staff who report the tests so replacing smear tests could ensure that waiting times for test results are kept to a minimum.”

The probe is about the size of a pencil (approx 5.5mm in diameter) and incorporates four gold electrodes mounted flush with the face of the probe and arranged equally spaced in a circle. Around 400 women who were recruited from the Trust’s colposcopy clinic with abnormal smear test results have already taken part in testing to develop accuracy and sensitivity in the equipment.

A £217,000 grant has been awarded to the Trust by NHS organisation, NEAT (New and Emerging Technology) to make further improvements to the probe. Funding will be used to develop a more accurate “stand alone” version of the probe that will use infrared to send data to the software for analysis. This will provide a much more practical and reliable method of data transfer than the current probe where information is sent down a wire.

It is hoped the probe could offer a solution for developing countries where 80 percent of cervical cancer incidences occur but due to economical reasons, cervical screening and laboratory testing are unavailable.

Results of the team’s latest research are to be published in BJOG: an international Journal of Obstetrics and Gynaecology this month.

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