In vitro studies of cryoablation of the endometrium

OBJECTIVE: The aims of this study were to quantify the tissue damage in vitro of a series of freezing protocols with the Endocryo (Spembley Medical Ltd, Andover, United Kingdom) cryoprobe for ablation of the endometrium and to determine the relative importance of the freezing parameters contributing to the cryolesion. STUDY DESIGN: The efficacy and safety of the Endocryo cryoprobe were assessed in vitro with 84 different experiments on freshly excised uterine specimens. Tissue necrosis was quantified by means of a histochemical technique after incubation of the uterine specimens under nearly physiologic conditions. RESULTS: A typical lesion was made up of a superficial area of tissue necrosis and a deeper area of sublethal damage. Tissue necrosis was >3 mm when the probe was in direct contact with the endometrium. Consistent tissue necrosis was only observed with tissue temperatures below -30 degrees C. Safe tissue damage was only consistently seen after less than or equal to 2 minutes of freezing. When the gap between the probe and the endometrium was filled with distention medium and was >2 mm, tissue damage was insufficient for clinical purposes irrespective of the medium used. CONCLUSION: The Endocryo cryoprobe provided a successful means of achieving endometrial ablation in vitro. The use of a uterine distention medium appeared to be of little value in improving the efficacy of the probe in vitro.