A comparison of flat and shallow conical tips for cervical cryotherapy.

BACKGROUND Although two types of cervical cryotherapy tips are widely used, there have been no randomized prospective comparison studies reported in the medical literature. Shallow conical tip proponents theorize that a greater depth of freeze near the os yields better treatment of cervical intraepithelial neoplasia (CIN) without elevating the squamocolumnar junction into the cervical canal. Flat tip proponents theorize an equally effective CIN treatment with lower incidence of posttreatment squamocolumnar junction location in the cervical canal. METHODS A comparative descriptive study was performed to evaluate 117 cryotherapy candidates with biopsy-proved CIN who were classified by location of their squamocolumnar junctions (ectocervix, at the os, or in the canal). They were then randomized to receive double-freeze cervical cryotherapy with either a flat or shallow conical tip. Four or more months later, repeated colposcopy and Papanicolaou smears were performed to assess resolution of CIN and posttreatment location of the squamocolumnar junction. RESULTS Eighty-four patients (71%) completed the study. Analysis indicated no important difference between the two tips in eliminating CIN. The squamocolumnar junction was colposcopically visualized at all posttreatment examinations. When the pretreatment squamocolumnar junction location was on the ectocervix, data analysis indicated that squamocolumnar junction movement was greater with the shallow conical tip (P = .037), particularly into the canal, where it is clinically more difficult to visualize (P = .019). There were no significant differences in movement of the squamocolumnar junction when it was originally at the os or in the canal. CONCLUSIONS This study found no significant difference in effectiveness of the two types of tips in eliminating CIN and supports the practice of using one type--either flat or shallow conical tips--to treat all candidates for cervical cryotherapy. Using the flat tip when the pretreatment squamocolumnar junction is on the ectocervix will allow easier posttreatment visualization of the squamocolumnar junction. Further studies with a greater number of subjects are indicated.