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The Clinical Significance of a Negative Loop Electrosurgical Cone Biopsy for High-Grade Dysplasia

Livasy, Chad A. MD; Moore, Dominic T. MPH; Van Le, Linda MD

doi: 10.1097/01.AOG.0000132803.88049.84
Original Research

OBJECTIVE: We sought to estimate the incidence and clinical significance of a negative therapeutic loop electrosurgical excision procedure (LEEP) and to evaluate patient specimens for limiting histologic features associated with a negative LEEP.

METHODS: We identified 674 patients with biopsy-confirmed high-grade cervical dysplasia who were treated with LEEP from 1991 through 2001. The results of these LEEP procedures were reviewed for the absence of dysplasia or the presence of cervical intraepithelial neoplasia stages 1–3. Computerized pathology files of patients were then reviewed through July 2002 to determine whether dysplasia recurred. Slides of negative LEEP specimens were reviewed to confirm the absence of dysplasia and to search for histologic features that may have limited our interpretation of the specimen.

RESULTS: Ninety-three (14%) of LEEP specimens reviewed were completely negative for dysplasia. Clinical follow-up was available on 75 of the 93 patients, with a median follow-up time of 2 years. Eighteen (24%) patients had subsequent positive follow-up, including carcinoma (n = 2), high-grade squamous intraepithelial lesions (n = 8), low-grade squamous intraepithelial lesion (n = 6), and atypical squamous cells of undetermined significance (n = 2). Patients with negative LEEPs had a recurrence rate similar to patients with positive LEEPs (24% versus 27%). Limiting histologic features were more commonly identified in negative LEEPs as compared with LEEPs containing dysplasia (16% versus 5%, P < .001).

CONCLUSION: A negative LEEP is not an uncommon finding, occurring in 14% (95% confidence interval 11–17%) of specimens at our institution. Negative LEEPs are more likely to contain histologic features that limit pathology interpretation. A negative LEEP is not a reassuring finding and was associated with a recurrence rate similar to those of a positive LEEP. Both negative and positive populations should be carefully followed.


A negative loop electrosurgical cone biopsy performed for high-grade dysplasia is not a reassuring finding, and continued close clinical follow-up is warranted for these patients.

From the *Department of Pathology and Lab Medicine, †Department of Biostatistics, ‡Department of Gynecologic Oncology, and §Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina.

Received January 20, 2004. Received in revised form April 15, 2004. Accepted April 22, 2004.

Address reprint requests to: Chad A. Livasy, MD, Department of Pathology and Laboratory Medicine, University of North Carolina, CB# 7525, Brinkhous-Bullitt Building, Chapel Hill, NC 27599–7525; e-mail:

Loop electrosurgical excision procedure (LEEP) is one of the most frequently used treatment options for the treatment of cervical intraepithelial neoplasia (CIN). Therapy with LEEP has been shown to be safe and efficacious.1–4 Reported success rates for the treatment of CIN range from 60% to 95%.1,2,4–6 Studies addressing the relationship between the histologic findings in LEEP specimens and subsequent recurrent disease have suggested that margin status is critical; however, these reports are conflicting.7–14 Endocervical gland involvement by dysplasia also has been shown to be associated with higher rates of recurrent dysplasia in both LEEP and cold-knife cone biopsies.11,15 Multiple-quadrant involvement of dysplasia is reported to be associated with a higher rate of dysplasia recurrence.11

The complete absence of dysplasia in a LEEP performed for high-grade dysplasia is an occasional finding of uncertain clinical significance. The purpose of this study was to estimate the incidence of a negative LEEP and its relationship to recurrence of disease. We also evaluated select histologic features found in LEEP specimens to determine whether these limited the ability to diagnose dysplasia.

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After obtaining internal review board approval, computerized anatomic pathology files at the University of North Carolina, Chapel Hill, were searched for all LEEP specimens performed for biopsy-confirmed high-grade squamous dysplasia from 1991 through 2001 and included specimens containing a diagnosis of CIN as well as negative specimens; results of LEEP diagnoses were reviewed to specifically identify cases in which no dysplasia was found. A negative LEEP was defined as a specimen in which no dysplasia was detected; a positive LEEP was one in which dysplasia was identified. Computerized files of these patients were evaluated through July 2002 for follow-up results from Pap tests, cervical biopsies, and/or hysterectomy. Pathology follow-up was available on 521 of the 674 patients identified, including 75 of 93 patients with a negative LEEP. Histologic slides from these 93 patients were reviewed to confirm the absence of dysplasia and evaluate for limiting histologic features, such as an absent transformation zone, the presence of cautery effect of the extent such as to limit definitive evaluation for dysplasia, or denuded epithelium. Prior cervical biopsies also were reviewed to confirm the presence of high-grade dysplasia (CIN 2 or CIN 3). For patients with negative LEEPs and limiting histologic features, procedure notes were reviewed to evaluate for technical and anatomic difficulties associated with the LEEP.

Loop electrosurgical excision procedure cone biopsies were received in a formalin-filled container and accessioned into the Department of Pathology database. A single suture designating the 12-o'clock position oriented the majority of specimens. The cone biopsy specimens were sectioned in a radial fashion to include ectocervix, transformation zone, and endocervix in each slice, if possible, and sequentially submitted in 4 cassettes corresponding to each of 4 quadrants, with 3 levels obtained from each block. A second endocervical pass (“tophat”) was received with some of the specimens. A board-certified academic pathologist performed microscopic examination of hematoxylin and eosin-stained slides prepared from each LEEP, and diagnoses were classified as negative for dysplasia, CIN stage 1, 2, or 3. A diagnosis of CIN was made when the squamous epithelium showed loss of maturation, nuclear hyperchromasia, and increased nuclear/cytoplasmic ratios characteristic for dysplasia. Results from post-LEEP Pap tests, biopsies, and hysterectomies were reviewed to estimate the incidence of recurrent CIN and were categorized as atypical squamous cells of undetermined significance (ASC-US), low-grade squamous intraepithelial lesion (LSIL), high-grade squamous intraepithelial lesions (HSIL), or carcinoma. Recurrence rates for negative LEEPs were compared with those showing HSIL with negative and positive margins. The presence of limiting histologic features was determined in both positive and negative groups.

The Fisher exact test was used to compare proportions for data that was categorized into 2 by 2 contingency tables. The Kaplan–Meier (or product limit) method was used to estimate the time to dysplasia for positive and negative LEEPs. The log-rank test was used to test for possible differences between these 2 estimated time-to-dysplasia curves. Exact 95% confidence intervals were calculated for each percentage of interest (estimate, 95% confidence interval [CI]). Statistical analyses were performed with SAS statistical software (SAS Institute Inc, Cary, NC).

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Women (n = 674) were aged 16 to 72 years with a median age of 28 years (Table 1). Ninety-three (14%, 95% CI 11–17%) women had a LEEP that was completely negative for dysplasia. Pathology follow-up was available on 521 patients, including 75 of the patients with negative LEEPs. The median follow-up time for each group (negative LEEP and positive LEEP) was 24 months. Eighteen (24%, 95% CI 15–35%) patients with a negative LEEP developed recurrence of an abnormal Pap test and/or were diagnosed with CIN on biopsy. There were 2 carcinomas, 8 cases of HSIL, 6 LSIL, and 2 ASC-US (cytology; Table 2). All cases of HSIL or carcinoma were confirmed by biopsy. One microinvasive squamous cell carcinoma and 1 adenosquamous carcinoma were diagnosed. For patients with a negative LEEP, the average follow-up time until the diagnosis of recurrent disease was 9 months, including 13.5 months for carcinomas, 6.75 months for HSIL, 11 months for LSIL, and 8 months for ASC-US. For patients with LEEPs showing HSIL, the average follow-up time to development of recurrent disease was 8.9 months for HSIL, 6.3 months for LSIL, and 12.5 months for ASC-US. The Kaplan–Meier (or product limit) method was used to calculate time-to-dysplasia curves (Fig. 1). A statistically significant difference in time-to-recurrent dysplasia between LEEP-negative and LEEP-positive patients was not demonstrated (P = .63, log-rank test).

Table 1

Table 1

Table 2

Table 2



The overall recurrence rate for LEEPs showing CIN stage 2–3 was 27% (95% CI 23–32%). One hundred seven patients developed recurrence as follows: 71 HSIL, 27 LSIL, and 9 ASC-US. Of these, 39% (95% CI 32–46%) of patients in whom LEEPS showed HSIL with positive margins demonstrated recurrent cervical dysplasia, whereas only 15% (95% CI 10–21%) of patients with LEEPS showing HSIL with negative margins recurred. Positive margins in LEEPs showing high-grade dysplasia were significantly associated with recurrent dysplasia (P < .001). When follow-up results from negative LEEP specimens are compared with those showing CIN stage 2–3 and negative margins (Table 3), the recurrence rate for negative LEEPs was higher (24% versus 15%, P = .10). When ASC-US Pap tests were excluded, the difference in recurrence rates was 21% compared with 12% (P = .08).

Table 3

Table 3

Histologic features limiting pathology interpretation were present in 15 (16%, 95% CI 9–25%) of the 93 negative LEEPs. Limiting histologic features included 2 cases with absent transformation zone, 3 cases with extensively denuded surface epithelium, 9 cases with extensive cautery artifact, and 1 case with both extensive cautery artifact and denuded epithelium. In comparison 27 (5%, 95% CI 3–7%) of the 581 LEEPs demonstrating dysplasia had specific mention of limiting histologic features in the report, including 23 cases with extensive cautery artifact and 4 cases with denuded squamous epithelium. Histologic features limiting pathology interpretation were more commonly identified in negative LEEPs (P < .001). In the LEEP cases that were positive for CIN, limiting histologic features, especially cautery artifact, were more of a problem in regard to accurate margin assessment rather than determining the presence or absence of dysplasia. A review of procedure notes in cases in which limiting features were identified was not notable for technical or anatomic difficulties.

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Loop electrosurgical excision procedure has proved to be a safe and effective treatment for cervical dysplasia.16 Prognostic factors based on LEEP specimens remain to be defined; however, margin status appears to be important.17 There are occasionally LEEPs performed that show no histologic abnormality. The clinical significance of this finding is unknown. Few studies have addressed the finding of a negative LEEP. Diakomanolis et al18 examined the incidence of negative cone biopsies performed for CIN stage 2–3 and found a negative rate of 16.5%. Clinical follow-up on the LEEP-negative patients was not reported.

There are several hypotheses to explain the absence of dysplasia in a LEEP specimen. These include postbiopsy regression of dysplasia, small foci of dysplasia removed in the LEEP but not sampled in the histologic sections, the presence of histologic features that preclude definitive pathology interpretation, and failure to remove dysplasia during the LEEP. All of these explanations are plausible and may explain cases of negative LEEPs.

The complete absence of dysplasia in a LEEP performed for high-grade dysplasia is not a rare finding, occurring in 14% (95% CI 11–17%) of cases at our institution. The patients with recurrent dysplasia after negative LEEP in this study frequently showed a short time interval (less than 1 year) between LEEP and recurrent dysplasia. High-grade squamous intraepithelial lesions were the most common type of recurrence. These findings indicate that there are some patients in whom dysplasia is not excised or ablated during the LEEP procedure, explaining the higher recurrence rate for negative LEEPs versus LEEPs showing CIN stage 2–3 and negative margins.

The majority of negative LEEPs did not contain any histologic features that limited pathology interpretation, but the overall rate of limiting histologic features was noted to be significantly higher in negative LEEPs (16%) compared with LEEPs showing dysplasia (5%; P < .001). The most common limiting histologic feature observed was extensive cautery artifact. Careful microscopic review of extensively cauterized epithelium observed in some of the negative LEEP cases did not reveal mitotic figures, apoptotic cells, or increased nuclear/cytoplasmic ratios to suggest the presence of cauterized HSIL, but the interpretation was limited. Absent transformation zone or denuded surface epithelium was a rare occurrence, identified in only 2% and 3%, respectively, of negative LEEPs. These limiting features likely impair the ability to definitively evaluate for small foci of dysplasia and may explain why the incidence of limiting features is higher in the negative LEEPs. There was no evidence that technical difficulties with the LEEP contributed to the presence of limiting histologic features. Variations in degree of cautery artifact and failure to sample the transformation zone may be dependent on the operator.

Approximately one quarter of all patients undergoing LEEP in this study went on to have a positive follow-up regardless of the presence or absence of dysplasia in their LEEPs. The 27% recurrence rate for LEEPs containing HSIL was similar to the 24% recurrence rate observed for negative LEEPs. Most recurrences in both groups (positive and negative LEEP) were HSIL and occurred early in follow-up. No statistical difference in time-to-recurrent dysplasia between the 2 groups was demonstrated. These findings show that patients with both positive and negative LEEPs should be followed equally aggressively. There are no set standards for the surveillance schedule after LEEP; however, recent studies suggest that follow-up in 6-month intervals for 1 year might be sufficient.19

Margin status in LEEPs showing high-grade dysplasia is important. Patients with LEEPs showing CIN stage 2–3 and positive margins had a recurrence rate significantly higher than patients with CIN stage 2–3 and negative margins. This study lends further support to the prognostic significance of margin status in patients showing CIN stage 2–3 in their LEEPs. Although negative margins appear to be a reassuring finding in LEEPs with HSIL, the status of other prognostic histologic factors, such as endocervical gland involvement by dysplasia and multifocal disease, should be considered when assessing risk for recurrent dysplasia.

The absence of dysplasia in a LEEP performed for biopsy-confirmed HSIL is not an uncommon finding. Overall, the recurrence rate for these patients was similar to patients with HSIL in their LEEP. The absence of dysplasia in a LEEP is not a reassuring finding, and close clinical follow-up with Pap cytology is warranted for these patients. Subsequent diagnosis of recurrence should be expected in up to one quarter of these patients. Patients with both positive and negative LEEPs should be carefully followed.

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© 2004 by The American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved.