Cryotherapy precision. Clinician's estimate of cryosurgical iceball lateral spread of freeze.

OBJECTIVE

To examine physicians' ability to estimate the lateral spread of freeze (LSF) of a cryosurgical iceball using three techniques.

DESIGN

A nonrandomized control trial of in vitro nitrous oxide cryosurgical procedures.

SETTING

Primary care residency training programs.

PARTICIPANTS

A convenience sample of 80 resident and faculty physicians from four family practice residency programs and one obstetrics and gynecology residency program.

INTERVENTIONS

After performing cryosurgery with standard naked-eye and colposcopic-assisted techniques, subjects used a new experimental cryosurgical iceball gauge (CIG) to estimate the LSF during cryotherapy.

MAIN OUTCOME MEASURES

LSF estimations reported physicians were compared simultaneously with those measured by an observer.

RESULTS

The mean (+/- SD) LSF estimation errors at the termination of freeze were as follows: 2.62 +/- 2.42 mm for the colposcopy technique, 2.00 +/- 2.16 mm for the naked-eye method, and 1.28 +/- 0.87 mm for the CIG technique. The range of maximum error was 6.5 to 11 mm for the colposcopic technique, 5.5 to 12.5 mm for the naked-eye method, and 3.0 to 4.0 mm for the CIG technique.

CONCLUSIONS

Overestimation of the LSF, which increases the risk of undertreatment and residual disease, was more common than underestimation. The CIG minimized perceptual error and provided the best cryosurgical precision.