Comparison of depth of necrosis achieved by CO 2- and N 2O-cryotherapy

Abstract

Objective To compare the depth of necrosis achieved using CO 2- and N 2O-cryotherapy. Method We treated 20 women with CO 2-cryotherapy and 20 with N 2O-cryotherapy 24 h prior to undergoing total hysterectomy for reasons unrelated to cervical cancer. Depth of necrosis in the ectocervix was measured on surgically removed tissue. Results The mean depth of necrosis for the anterior lip achieved by N 2O-cryotherapy was 5.3 mm compared with 3.4 mm by CO 2-cryotherapy ( P < 0.001). We found similar results for the posterior lip (5.0 vs 3.1 mm; P < 0.001). N 2O-cryotherapy was more likely than CO 2-cryotherapy to achieve a depth of necrosis of ≥ 4.8 mm for the anterior lip (75% vs 15%; P < 0.001) and posterior lip (60% vs 5%; P < 0.001). Conclusions Our study showed that CO 2-cryotherapy may not achieve the depth of necrosis necessary to completely destroy cervical precancer and therefore may be less robust than N 2O-cryotherapy.