Background

Cryotherapy is often used to treat cervical precancer in developing countries. There are different methods and cryogen gases used for cryotherapy, including the freeze-flush-freeze (cough) technique employed to minimize gas blockage. However, there is limited information to compare their effectiveness.

Methods

Using a tissue model, we compared temperature-time curves for four cryotherapy methods: uninterrupted freezing with nitrous oxide (N₂O) and carbon dioxide (CO₂), and two methods using a standard and extended version of the cough technique with CO₂.

Results

Uninterrupted freezing with both N₂O and CO₂ produced tissue temperatures less than -20°C (-40°C and -30°C respectively). CO₂ cryotherapy procedures using the two cough techniques produced temperatures greater than -20°C in the model tissue.

Conclusion

CO₂ cryotherapy using the cough technique may not achieve sufficiently low temperatures to produce the desired therapeutic effect. Other alternatives to the prevention of gas blockage should be developed.