Comparison of depth of necrosis achieved by CO2- and N2O-cryotherapy.

OBJECTIVE

To compare the depth of necrosis achieved using CO2- and N2O-cryotherapy.

METHOD: We treated 20 women with CO2-cryotherapy and 20 with N2O-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 N2O-cryotherapy was 5.3 mm compared with 3.4 mm by CO2-cryotherapy (P<0.001). We found similar results for the posterior lip (5.0 vs 3.1 mm; P<0.001). N2O-cryotherapy was more likely than CO2-cryotherapy to achieve a depth of necrosis of >or=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 CO2-cryotherapy may not achieve the depth of necrosis necessary to completely destroy cervical precancer and therefore may be less robust than N2O-cryotherapy.