Thermal artefact after diathermy loop excision and laser excision cone biopsy

Whether or not thermal artefact precludes accurate histopathologic assessme nt of excision biopsies of the uterine cervix is currently controversial. S ome authors state that margins cannot be assessed at:all while others feel that the pathologist can 'see through' the artefact in the majority of case s, Over a 7-month period, 164 patients had loop excision and 84 patients ha d laser cone biopsy, The zone of coagulation at the specimen periphery was measured and the adequacy of excision assessed. The average width for this zone of coagulation in diathermy loop was 0.32 mm and for laser cone biopsi es was 0.31 nun. In 12% of the loop specimens the line of excision was comp romised by dysplasia or its assessment was rendered uncertain by thermal ar tefact. This was far more common in fragmented specimens (20%) compared to those removed as a single specimen (6%). In this study, 40% of patients had fragmented loop specimens. Thus, in attempting to replace cone biopsy with loop excision, we are asking pathologists to reassemble a pathologic jigsa w, then look through the thermal artefact far a decision on margins. We bel ieve that this fragmentation should preclude the use of loop excision for l esions which would previously have been managed by cone biopsy.