The large loop excision of the transformation zone cut or blend thermal artefact study: a randomized controlled trial

The objective of this randomized controlled trial was to determine whether the pure cut setting results in less thermal artefact than the traditional blend setting when performing a large loop excision of the transformation zone (LLETZ). Forty-nine consenting women were randomized to undergo an LLETZ procedure using either the pure cut or the blend setting. Two histopathologists, who were blind to the randomization, examined the specimens and then graded and measured the degree of thermal artefact. No significant difference was noted at the epithelial margin. At the deep stromal margins, in the blend group, the mean thickness of thermal artefact was 0.382 mm (95% CI, 0.350-0.414) and in the cut group 0.325 mm (95% CI, 0.297-0.353). This was statistically significant. No significant difference was detected in terms of grading of thermal artefact, the presence of dysplasia at the specimen margins, or in positive follow-up smears. Although there was less thermal artefact at the deep stromal margin, cautery at this margin does not generally interfere with pathological assessment of the specimen and the pure cut setting does not produce a clinically significant decrease in the degree of thermal artefact.