Cryotherapy precision. Clinician's estimate of cryosurgical iceball lateral spread of freeze
D. G. Ferris, G. R. Crawley, E. G. Baxley, R. Line, K. Ellis and P. Wagner
Department of Family Medicine, Medical College of Georgia, Augusta.
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.
