Thermal Ablation for Cervical Pre-Cancer Lesions

This Sexual and Reproductive Health and Rights (STARS) - Cervical Cancer Screening and Treatment module allows nurses, midwives, clinical officers, and medical officers to become confident and competent in performing thermal ablation of cervical pre-cancer lesions as part of cervical cancer screening and treatment procedures performed in primary health care facilities and mobile units in resource-constrained settings.

Learning Objectives[edit | edit source]

By the end of this module, learners will be able to:

1. counsel women before and after thermal ablation;
2. explain principles and techniques of thermal ablation;
3. perform thermal ablation as appropriate.

Anatomy and Physiology of the Female Genital Tract[edit | edit source]

• Cervix is the lower part of the uterus that projects through the anterior wall of the vagina.^[1]
• The cervix is covered by squamous epithelium and columnar epithelium that meet at the squamocolumnar junction (SCJ).
• The columnar epithelium on the ectocervix is replaced by squamous epithelium through a process known as metaplasia.
• The area of the cervix where metaplasia occurs is known as the transformation zone (TZ).
• The TZ can be identified by certain features like crypt openings, nabothian follicles, etc.
• In postmenopausal women, the SCJ moves into the endocervical canal and part of the TZ may not be visible.

Treatment of Cervical Pre-cancers by Thermal Ablation[edit | edit source]

Thermal ablation, also called "cold coagulation" or thermocoagulation, is another ablative treatment for cervical intraepithelial neoplasia.^[2] The equipment is simple, lightweight (devices can weigh much less than 2 kg), and is easily portable to low- and middle-income countries (LMICs) field clinics. Treatment is based on a 20–40 second application (multiple if needed) of a reusable metallic probe that is electrically heated to approximately 100 °C, leading to epithelial and stromal destruction. Like cryotherapy, thermal ablation is provided by a variety of health care personnel, including primary health care workers, and typically performed without anesthesia.

The World Health Organization currently recommends thermocoagulation as an acceptable option to cryotherapy for cervical cancer "screen-and-treat" programs in LMICs.^[3]

Eligibility for Thermal Ablation[edit | edit source]

Eligibility for treatment should be assessed by colposcopy (if available) or by naked eye examination of cervix after applying 3–5% acetic acid for 1 minute.^[2]

Clinicians usually describe what they see when performing visual inspection (for example, if the TZ is fully visible; if the whole lesion is visible; if the lesion extends into the endocervix), and then consider if the probe can reach the whole lesion.

Clinicians can consider using the International Federation for Cervical Pathology and Colposcopy's classification of three types of Transformation Zone (TZ), characterised by the size and site:

• A type 1 TZ is completely ectocervical and is therefore fully visible.
• A type 2 TZ is partially endocervical but is still fully visible. It may be shallow and within range of an ablative probe or may extend beyond reach of an ablative probe.
• A type 3 TZ extends out of view up the endocervical canal, i.e., the squamocolumnar junction (SCJ), and is not fully visible.

Following assessment as described above, women who screen positive, but there is no suspicion of invasive or glandular disease, (i.e. adenocarcinoma or adenocarcinoma in situ), are eligible for ablative therapy if:

• the TZ is fully visible, the whole lesion is visible and it does not extend into the endocervix, or
• the lesion is type 1 TZ; or
• the lesion is type 2 TZ where the probe tip will achieve complete ablation of the SCJ epithelium, i.e., where it can reach the upper limit of the TZ. Sometimes the SCJ can be seen high in the canal but a probe tip would not reach it.

Women who screen positive are not eligible for ablative therapy if there is any suspicion of invasive or glandular disease, (i.e. adenocarcinoma or adenocarcinoma in situ), and:

• the TZ is not fully visible because it is endocervical (Type 3 TZ); or
• it is a Type 2 TZ where the SCJ is out of reach of the probe tip.

Intervals for Follow-Up[edit | edit source]

Intervals for follow-up should be conducted according to the WHO guidelines for treatment of cervical intraepithelial neoplasia 2–3 and adenocarcinoma in situ,^[2][4] and the WHO guidelines for screening and treatment of precancerous lesions for cervical cancer prevention.^[5]

According to those recommendations, all women who have received treatment should receive post-treatment follow-up at 1 year to ensure effectiveness of treatment.^[2]

Post treatment follow-up is critical, in particular for women living with HIV or women of unknown HIV status in areas with high endemic HIV infection.

Infection Prevention Practices[edit | edit source]

Infection prevention is of paramount importance in all health interventions.^[1]

The basic steps for processing instruments, surgical gloves and other items are: decontamination, cleaning, high pressure saturated steam sterilization, and high-level disinfection (HLD).

HLD can be done either by boiling or chemical methods using 0.5% chlorine solution or 2% glutaraldehyde.

Biomedical wastes should be disposed-off in appropriate coloured bins.

Checklist for Thermal Ablation[edit | edit source]

*The highlighted steps are considered as critical^[1]

Counselling Prior to Thermal Ablation[edit | edit source]

Greet the woman respectfully and introduce yourself*

Explain to the woman why the treatment is recommended and describe the procedure*^[1]

Exclude pregnancy by asking last menstrual period (LMP) and do urine pregnancy test if amenorrhoea is present

Tell her about what side effects to expect and the alternatives to thermal ablation

Obtain informed consent for thermal ablation

Setting Up of Equipment[edit | edit source]

Check that instruments, supplies and light source are available and ready to use^[1]

Check that the thermocoagulator is connected to a power source and is ready for use*

Tell the woman what is going to be done and encourage her to ask questions

Check that the woman has recently (not more than 30 minutes earlier) emptied her bladder

Help her on to the examination table and drape her

Wash hands thoroughly with soap and water and air dry them

Put on new examination or high-level disinfected surgical gloves

Arrange instruments and supplies on a high-level disinfected tray or container

Steps of Thermal Ablation[edit | edit source]

Insert an appropriate sized speculum and fix the blades so that the entire cervix can be seen clearly^[1]

Move the light source so that the cervix can be visualized clearly

Apply 3–5% dilute acetic acid and identify:*

• SCJ

• Limits of the lesion

• TZ and area to treat

Select a probe of appropriate size to cover the cervix.

Connect the probe to the thermocoagulator.

Apply the thermocoagulator probe on the area of the cervix to be treated.*

Make sure that the probe is free from the vaginal wall.*

Check if the entire TZ has been treated. If not, then repeat the procedure so as to treat the entire TZ including the lesion on the ectocervix (1–5 overlapping

applications can be used)

Remove the probe gently taking care not to touch the vulva or vagina with the probe to avoid unnecessary burns*

Check to be sure the woman is not having excessive cramps

Documentation[edit | edit source]

Complete the documentation to record the treatment*^[1]

Draw a map of the cervix and the treated area in the woman's case record form*

Post-Procedure Counselling[edit | edit source]

Advise about post-treatment care and follow-up instructions*^[1]

Counsel patient on expected symptoms after treatment, which could including mild cramping and vaginal discharge^[6]

Advise patient to abstain from sexual intercourse for 4 weeks post-treatment

Return to the clinic immediately if patient has concerning symptoms, including severe pain, heavy bleeding, or fever

Decontamination and Sterilization[edit | edit source]

Dispose of the swabs in appropriate disposal bags^[1]

Remove the speculum and place it in 0.5% chlorine solution for 10 minutes

Clean and disinfect the probe in accordance with the manufacturer's instructions.

Immerse both gloved hands in 0.5% chlorine solution.

Remove gloves by turning them inside out

• If disposing off the gloves, place them in a leak-proof container or plastic bag.
• If reusing surgical gloves, submerge them in 0.5% chlorine solution for 10 minutes for decontamination

Wash hands thoroughly with soap and water and dry with clean, dry cloth or air dry

Self assessment[edit | edit source]

References[edit | edit source]

Sections of the STARS - Cervical Cancer Screening and Treatment module are copied or adapted from: Training of health staff in VIA, HPV detection test and cryotherapy - Facilitators' guide. New Delhi: World Health Organization, Regional Office for South-East Asia; 2017. Licence: CC-BY-NC-SA-3.0 IGO; and WHO guidelines for the use of thermal ablation for cervical pre-cancer lesions. Geneva: World Health Organization; 2019. Licence: CC-BY-NC-SA-3.0 IGO. The World Health Organization (WHO) is not responsible for the content or accuracy of any translation. The original English edition shall be the binding and authentic edition.