A Comparative Study of Two Methods of Large Loop Excision of the Transformation Zone

Abstract

This paper presents a retrospective comparison of large loop excision of the transformation zone (LLETZ) performed conventionally (CLLETZ) or using the technique (THLLETZ). In the top-hat procedure, the transformation zone is excised with two separate passes of a loop electrode. The first is a superficial exocervical excision, and the second pass excises a deeper endocervical specimen. Study subjects were 513 consecutive patients at St. George Hospital during 1998 and 1999 who had undergone a LLETZ procedure for treatment of cervical intraepithelial neoplasia (CIN). The choice of procedure depended on the colposcopists performing the procedures, who, in general, preferred either CLLETZ or THLLETZ exclusively. Patients underwent a follow-up colposcopy and cytology 4 to 6 months after the procedure. Two hundred eighty-six (56%) women were treated with CLLETZ and 227 (44%) had THLLETZ. The initial colposcopic examination identified 137 (48%) cases of CIN 1 in patients undergoing CLLETZ and 67 (30%) in the THLLETZ group. High-grade CIN (CIN 2 or 3) was diagnosed colposcopically in 139 (49%) patients undergoing CLLETZ and 154 (67%) patients undergoing THLLETZ (P = .026). Histologic diagnoses of the CLLETZ specimen included 143 patients with CIN 1 (49%), 37 CIN 2 (13%), 88 CIN 3 (31%), and 2 microinvasive carcinomas (high-grade lesions = 44%). In the THLLETZ specimen, there were 89 (39%) CIN 1, 34 CIN 2 (15%), 93 (41%) CIN 3, and 4 microinvasive carcinomas. A total of 57% of THLLETZ specimens contained high-grade lesions (P = .01). No CIN was found in 16 (6%) patients undergoing CLLETZ or in 7 (3%) patients undergoing THLLETZ. The mean depth of the CLLETZ excision was 12.1 mm (range, 3-25 mm). By comparison, in the THLLETZ group, the mean of the total depth of excision (first plus second pass) was 20.8 mm (range, 5-35 mm; P <.0001). Ten (4.4%) of the women undergoing THLLETZ had CIN in the apical endocervical specimen (second pass). Four of these patients were among the 14 patients undergoing THLLETZ who had positive endocervical margins in the first-pass specimen. Operative complications were similar for both procedures. Significant bleeding occurred in 3 patients (1.04%) in the CLLETZ group, 2 of whom required hospital admission, and 7 (3.08%) patients undergoing THLLETZ, of whom 4 were hospitalized. Ninety-four percent of the patients who underwent CLLETZ returned for the follow-up colposcopy visit. The transformation zone was not entirely visible (incomplete colposcopy) in 73 (26.9%) of these women. Of 207 (91%) patients undergoing THLLETZ who had a follow-up colposcopy, the transformation zone was not visible in 128 (60%). Discounting the 14 and 27, respectively, of these patients who also had incomplete initial examinations, the rate of incomplete colposcopy postoperatively was 21.7% in the CLLETZ group compared with 48.7% in the THLLETZ group (P <.0001). In addition, cervical stenosis, defined as difficulty or inability in obtaining an endocervical brush smear, was encountered at follow up in 21 (7.7%) patients undergoing CLLETZ and 64 (30.9%) patients undergoing THLLETZ (P <.0001). Follow-up cytology data were available for 121 women who were treated with CLLETZ and 170 who were treated with THLLETZ. Inadequate smears were diagnosed in 5 (4.1%) of the CLLETZ group compared with 20 (11.7%) of the THLLETZ group (P =.02). Eleven women undergoing CLLETZ (4%) and 12 women undergoing THLLETZ (5.8%) were diagnosed with residual CIN at the follow-up examination.