Treatment by cryotherapy – Steps
- Counsel the woman, and obtain informed consent.
- Colposcopically re-evaluate the lesion and ensure that:
- The lesion is completely ectocervical, with a type 1 TZ.
- The lesion does not extend to more than 75% of the cervix.
- The lesion can be fully covered by the largest cryotip.
- The lesion does not have any features suspicious of cancer.
- Remove the colposcope, and use a focusing light for the procedure.
- No anaesthesia is required for cryotherapy.
- Select a probe with a tip of the appropriate diameter that will cover the lesion completely. Attach the probe to the handle grip (cryogun).
- Connect the valve with the pressure gauge to the gas cylinder. The pressure of the gas cylinder should be 40–70 kg/cm2 when the gas is flowing (indicator in the green zone).
- Wipe the cryotip with saline or lubricant, to ensure adequate thermal contact.
- Apply the probe tip firmly to the cervix with the centre of the tip on the external os.
- Check that the vaginal walls are not touching the probe tip.
- Press the trigger on the handgrip so that gas starts flowing, and start the timer.
- Check for the formation of ice at the tip of the probe.
- Release the trigger after 3 minutes, when you will see an ice ball formed over the cervix extending 4–5 mm beyond the edge of the tip.
- If the ice ball has formed adequately, the probe tip will remain stuck to the cervix.
- Wait for 5 minutes for thawing, when the ice will melt and the probe may detach from the cervix.
- Reapply the probe at the same place as before, and freeze the cervix for another 3 minutes.
- Release the trigger and wait until the ice melts and the probe detaches from the cervix on its own.
- The cervix will have a white crater, which indicates that the cervix is properly frozen.
- Remove the speculum gently.
- Ask the woman to continue lying down for 5 minutes before letting her getting up.
- Counsel the woman, and give appropriate follow-up advice.
IARC, 150 Cours Albert Thomas, 69372 Lyon CEDEX 08, France - Tel: +33 (0)4 72 73 84 85 - Fax: +33 (0)4 72 73 85 75