Comparison of depth of necrosis using cryotherapy by gas and number of freeze cycles

Miriam Cremer, Lauren Ditzian, Jennifer L. Winkler, José Jerónimo, Jered Singleton, Henry Valdivia Franco, Mauricio Maza, Elizabeth Conlisk, Julia Gage, Philip Castle, Carlos Santos

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


OBJECTIVE: This study aimed to establish the noninferiority of a single-freeze application with CO2 or N2O compared with the standard double freeze with N2O for cryotherapy treatment.

MATERIALS AND METHODS: Sixty women undergoing hysterectomy for reasons other than cervical cancer or precancer were randomized to 1 of 3 techniques as follows: (1) double freeze with N2O, (2) single freeze with N2O, or (3) single freeze with CO2. The cervix was separated and cut into anterior and posterior segments, and the deepest area of necrosis was recorded. Comparisons were made using regression analysis. The margin of noninferiority was defined as 0.8 mm.

RESULTS: On the anterior lip, a single freeze with N2O was noninferior to a double freeze of the same gas, but on the posterior lip, the single freeze was not. The single freeze of CO2 did not provide sufficient depth of necrosis in either lip to infer noninferiority versus the double freeze with N2O.

CONCLUSIONS: A single freeze with N2O is noninferior to a double-freeze technique in the anterior but not the posterior lip. However, the result for posterior lips was close to reaching statistical significance. In addition, CO2 had approximately 1 mm shallower depth of necrosis compared with N2O techniques; however, the clinical implications are unknown. Given the extensive use of CO2 globally, further clinical evaluation is needed.

Original languageEnglish (US)
Pages (from-to)1-6
Number of pages6
JournalJournal of lower genital tract disease
Issue number1
StatePublished - Jan 13 2015
Externally publishedYes


  • carbon dioxide
  • cervical precancer
  • cryotherapy
  • depth of necrosis
  • nitrous oxide

ASJC Scopus subject areas

  • Obstetrics and Gynecology


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