Objective: To compare two excisional treatments, laser cone biopsy and large loop excision of the transformation zone (LLETZ), in terms of the volume of tissue removed, and to determine the relation between the height and the total volume of the cone specimen.
Design: Retrospective cross-sectional study.
Setting: Large teaching hospital in London.
Population: A total of 1136 eligible excisional treatments (laser cone or large loop excision of the transformation zone, LLETZ).
Methods: Eligible excisional treatments (laser cone or LLETZ) performed between 1 January 2002 and 31 December 2007 in our colposcopy unit were identified using the Infoflex(R) database. The total volume of the cone biopsy was calculated mathematically using the data provided in the histopathology reports.
Main outcome measures: The volume of the cone biopsy was compared with the technique of excision and the histology grades.
Results: Three hundred and thirty-nine laser cone biopsies were performed, whereas 797 LLETZ biopsies were recorded, during the study period. There was no difference in the mean age in the two groups. However, there is a proportional increase in the volume of the cone as the height of the cone increases, and a significant number of the values are skewed, suggesting that the diameter of the base of the cone contributes significantly to the total volume. Laser cone biopsies (median volume 1.84 cm(3), 95% CI 1.98-2.54 cm(3)) account for a larger volume of tissue excised compared with LLETZ (median volume 0.78 cm(3), 95% CI 0.91-1.02 cm(3)) (P < 0.0001). This relationship is not altered when the two procedures are stratified for grade of lesion, i.e. excision for low-grade cervical intraepithelial neoplasia (CIN) (laser median volume 1.55 cm(3), 95% CI 1.46-2.06; LLETZ median volume 0.62 cm(3), 95% CI 0.73-0.88 cm(3)) (P < 0.0001) or high-grade CIN (laser median volume 1.84 cm(3), 95% CI 2.11-2.53 cm(3); LLETZ median volume 0.82 cm(3), 95% CI 0.94-1.07 cm(3)) (P < 0.0001).
Conclusions: The volume of cervical tissue removed during laser conisation is significantly more than that removed with LLETZ. The indication of the cone biopsy does influence the volume of tissue removed.