Comparison of specimens removed by CO2 laser conization and the loop electrosurgical excision procedure

A comparison is made of the histologic changes in the cervical epithelium and stroma following CO2 laser conization and office excisional biopsy of cervical tissue using the loop electrosurgical excision procedure. In both types of specimens, two zones of thermal injury were detected. The zone at the margin of resection measured approximately 50 microns in thickness and was characterized by extensive carbonization and charring. The other zone was much more variable in thickness and characterized by tissue coagulation, but lacked charring. No significant difference in the biocharacteristics or extent of thermal damage was detected between the methods. For 11 specimens obtained with the CO2 laser, the coagulated zone ranged from 130-750 microns in greatest thickness; the mean thickness was 411 microns. For 40 specimens obtained using the loop procedure, the range of thickness of the coagulated zone was 150-830 microns, and the mean thickness was 396 microns. The difference in the mean value of thermal injury (measured in microns) between the laser and loop procedures was not significant (Student t test; P = .79). Extensive areas of carbonization and epithelial distortion at the margins of excision were only occasionally present in specimens obtained by the electrosurgical excision procedure but almost invariably present in CO2 laser specimens. However, in all cases it was possible to evaluate the epithelium and the stroma both histologically and cytologically.