Study of the depth of tissue destruction of cervical epithelium using either the Semm thermal coagulator, the Liger thermal coagulator or cryosurgery

Cryotherapy is extensively used to treat ectocervical premalignant lesions that occupy less than 75% of cervix and can be covered by the cryo-probe. For low- and middle-income countries (LMIC) the World Health Organization (WHO) recommends that cryotherapy be used to treat women positive on screening tests (HPV Test or Visual Inspection with Acetic Acid (VIA)), even without colposcopic or histologic verification of disease. This ‘single visit approach’ will significantly increase the demand for cryotherapy in these countries. Unfortunately, cryotherapy has certain logistic disadvantages that can limit its use, such as procuring refrigerant gas, essential for the technique, or ensuring its regular supply is a major problem in many LMICs. Transporting heavy tanks of gas is inconvenient and sometimes impossible in remote areas. The blockage of the nozzle, due to impurities, leakage of gas, etc., are other possible technical difficulties with the procedure.  For this reason, it is essential to find an alternative to cryotherapy that will be suitable and sustainable for LMICs. Thermal coagulation, using a portable thermal coagulator, destroys the transformation zone at temperatures in the 100 to 120oC range. Thermal coagulation was popular in some regions (especially Scotland in the UK) in the 1970s where very high success rates were documented in several long-term studies using the SemmTM coagulator (WISAP Medical Technology, Germany).The technique is as simple as cryotherapy, is an outpatient procedure, easily learned and may be performed by a range of providers including nurses. No refrigerant gas is required and multiple applications of the probe are possible to treat large lesions. In a recent review, the effectiveness of cold coagulation to treat high-grade lesions was observed to be even better than cryotherapy.

LigerTM Medical, USA has developed a novel thermal coagulator for the treatment of cervical precancers, which has design advantages over the Semm coagulator.  Briefly, it is a hand held, lightweight, inexpensive, battery operated, cordless device, which can perform at least 30 procedures with a single fully charged and rechargeable battery. It is likely to be suitable for programmes of cervical cancer prevention in LMICs. Preliminary in vitro studies by the manufacturers suggest that it reaches the needed temperature quicker than the Semm’s coagulator, maintains the preset temperature more consistently than the Semm model, achieves a similar depth of destruction and does not produce smoke nor stick to the tissue post-treatment.

Our proposed study intends to assess the depth of tissue destruction achieved by 20, 30 and 45 seconds application of thermal ablation (by both the Semm’s and Liger’s coagulators) in the cervical transformation zone epithelium. This will be done in women who are listed for a hysterectomy for benign reasons. The depth of tissue destruction achieved by the thermal ablation equipment will be compared to that achieved by double-freeze cryotherapy – the standard of care.