Loop electrosurgical excision procedure (LEEP) is a common treatment for cervical intraepithelial neoplasia (CIN), with success rates of 60 to 95 percent reported. Several studies have examined the relationship between histologic abnormalities in LEEP specimens and disease recurrence. Occasionally, however, a LEEP sample shows no histologic abnormality. The clinical implications of a negative sample are unknown. Livasy and colleagues studied the medical and histologic records of 674 patients to determine the incidence and clinical significance of negative LEEP samples.

The study included all women at one university medical center who received LEEP therapy for high-grade dysplasia between 1991 and 2001. Follow-up results from Papanicolaou (Pap) smears, cervical biopsies, and hysterectomies through July 2002 were evaluated.

Ninety-three (14 percent) of the women had negative LEEP specimens. Follow-up data were available on 75 of these patients and 446 of the others. A recurrence of abnormality (i.e., abnormal Pap smear or other diagnosis of CIN) was documented in 18 (24 percent) of the women who had negative LEEP samples compared with 107 (27 percent) of those with positive histologic findings. Recurrent abnormalities in the women with negative LEEP samples consisted of two carcinomas, eight high-grade squamous intraepithelial lesions, six low-grade squamous intraepithelial lesions, and two atypical cells of undetermined significance. Factors that may limit histologic examination, such as cautery, were identified in 15 (16 percent) of the negative LEEP samples compared with 27 (5 percent) of the positive LEEP samples.

the authors conclude that negative histology, while not rare, should not be interpreted as a benign finding, as subsequent abnormality rates were similar in women with negative LEEP samples and those with histologic abnormality. They note that the incidence of factors limiting complete pathological examination was significantly higher in negative LEEP specimens than in positive, and recommend close monitoring of all women who are treated for dysplasia, regardless of LEEP histology.