Methods	Multi-centre RCT at the Glostrup Hospital and the Hvidovre Hospital in Denmark
Participants	222 women with a histological diagnosis of CIN II-III, or persistent CIN I Median age (years) in the trial at the Glostrup Hospital was 33 (range: 18-74) in the loop group and 32 (range: 21-58) in the laser group At the Hvidovre Hospital the median age (years) was 31 (range: 18-56) in the loop group and 29 (range: 19-75) in the laser group The age range in the trial was 18-75 years and there was no significant difference in age between the 4 groups. There were 9 (4%) women with CIN 1, 45 (20%) with CIN 2 and 168 (76%) with CIN 3
Interventions	Laser conisation: performed using a CO2 laser (A: Sharplan Model 733A, B: Sharplan model 1050, Laser Industries Ltd) attached to the colposcope. The laser energy was delivered in continuous (A) or pulsatile pulse mode (B) using power densities ranging from 3000-5500 W/cm2. After removal of the tissue a defocused beam coagulated the cervical lesion Diathermy loop conisation: this was done without simultaneous colposcopic guidance. The excision zone and depth was determined by the colposcopic description in the patients record, whether atypical cytology and/or histology was present in samples from the exocervix, the endocervix, or both, and guided by application of acetic acid solution and Schiller’s iodine. The size and shape of the diathermy loop (Niko-Med) were chosen among three (wideXdeep: 10X5 mm, 15X7 mm, or 20X9 mm) to excise the lesion in a single sweep. Larger lesions required excision in two or three sections. A Davol model 2000 BP II(A) or 2000(B) (Electro Medical Systems) electrosurgical generator supplied the diathermy power. A combination of cutting and coagulation was used for excision. The power setting was adjusted according to the size of the loop and the cone. Hemostasis was achieved by ball diathermy
Outcomes	Peri-operative severe bleeding Bleeding (ordinal scale: none, >1day, 1-7 days, 8-14 days, 15-31 days) Time for excision Vaginal discharge Cervical stenosis
Notes	Median duration of procedure (mins) at the Glostrup Hospital was 4 (range: 0.5-60) in the loop group and 20 (range: 3.5-60) in the laser group Median duration of procedure (mins) at the Hvidovre Hospital was 3 (range: 1-14) in the loop group and 10 (range: 3-25) in the laser group Residual disease based on abnormal cytology at 6 or 9 months
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Yes	“Women admitted for conization were allocated by a computer-generated randomisation code to either loop or laser excision”
Allocation concealment?	Unclear	Not reported
Blinding? All outcomes	Unclear	Not reported
Incomplete outcome data addressed? All outcomes	Yes	% of women analysed: 222/222 (100%)
Free of selective reporting?	Unclear	Insufficient information to permit judgement
Free of other bias?	Unclear	Insufficient information to assess whether an important risk of bias exists

CIN: cervical intraepithelial neoplasia

LLETZ: large loop excision of the transformation zone