Longitudinal EIS study published in Journal of Electrical Bioimpedance

Friday 6th November 2020

Prognostic value of Electrical Impedance Spectroscopy (EIS) when used as an adjunct to Colposcopy – a longitudinal study

B. H. Brown, P.E. Highfield and J. A. Tidy

The poor performance of colposcopy is often a concern to colposcopists when discharging women from clinic after a negative colposcopy. The use of adjuncts in colposcopy, such as ZedScanTM has been shown to increase the detection of CIN2+ [1]. However, long term outcome data from women who have been discharged to community-based screening is lacking.

This current investigation reports the results of a longitudinal service evaluation of patients who were negative at the initial (index) colposcopy but who, in some cases, were found to develop CIN2+ over the subsequent three years. The investigation also looked for any association between the index Electrical Impedance Spectroscopy (EIS) measurements and the subsequent development of disease.


  • Where a colposcopy examination was negative but ZedScan indicated a positive probability of high grade disease, the results from a 3 year follow up of 847 women showed that there was a 1.69% risk of developing CIN2+ each year.
  • In the sub group where colposcopy and ZedScan were both positive for high grade disease but a subsequent biopsy result was negative, the annual risk rose to 4.57% over the following 3 years.
  • In the sub group of women where there were three or more ZedScan positive points at the initial colposcopy, the annual risk of developing CIN2+ rose to 9.62%.

This suggests for management of patients in the higher risk sub groups, they should be re-examined in 12 months and not discharged to routine screening.

(1) Tidy JA, Brown BH, Healey TJ, Daayana S, Martin M, Prendiville W, et al. Accuracy of detection of high-grade cervical intraepithelial neoplasia using electrical impedance spectroscopy with colposcopy. BJOG 2013; 120: 400–411. https://doi.org/10.1111/1471-0528.12096

Read the full study publication here or download below

This paper was presented as an abstract poster at BSCCP 2021. Watch Prof Tidy presenting the poster here