Treatment by cryotherapy – Steps
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- Counsel the woman, and obtain informed consent.
- Re-evaluate the lesion (by performing colposcopy or with naked-eye examination after application of 3–5% acetic acid or with a magnifying device after application of 3–5% acetic acid) and ensure that:
- the squamocolumnar junction (SCJ) is fully visible and is on the ectocervix or at the external os;
- if there is a visible lesion, it is on the ectocervix without any extension to the endocervix or to the vagina;
- if there is a visible lesion, it does not occupy more than 75% of the ectocervix;
- the transformation zone or the lesion (when a lesion is present) can be fully covered by the tip of the largest cryotherapy probe;
- there is no suspicion of invasive cancer (on naked-eye examination or on colposcopy or on earlier cytology or histopathology reports); and
- there is no suspicion of adenocarcinoma in situ (e.g. a cytology report suggesting abnormal glandular cells).
- No anaesthesia is required.
- If required, obtain a punch biopsy from the cervix. Stop the bleeding with Monsel’s paste or silver nitrate or pressure before proceeding to the next steps.
- Select a probe with a tip of the appropriate diameter that will cover the transformation zone or 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 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; 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.
- Always follow the double-freeze method of a 3–5–3 cycle (3 minutes of freezing, 5 minutes of thawing, and 3 minutes of freezing).
- 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 get up.
- Counsel the woman, and give appropriate follow-up advice.
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