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.
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