Objective: To assess the accuracy of the cervical smear and colposcopy in diagnosing low grade squamous intraepithelial lesions (LSIL), and the natural history of LSIL.
Method: The cytological, colposcopic and histological findings of 145 patients with a smear diagnosis of LSIL were compared, and the final outcome studied.
Results: The diagnosis of LSIL either by cytology alone or in combination with colposcopy was associated with a rate of overdiagnosis of 11.7% and 6.9%, respectively, and a rate of underdiagnosis of 31.0% and 26.2%, respectively. Spontaneous regression of lesions occurred in 81.1% of patients with proven LSIL, with regression within 24 months in 4/5 of cases.
Conclusions: The degree of dysplasia shown in the cervical smear correlated poorly with histology. All patients with cervical smear showing LSIL should have colposcopy and colposcopic-directed biopsy to exclude the presence of more advanced lesions. In the absence of some serious lesions, it is then acceptable to observe the patient for 24 months before adopting definite treatment, as spontaneous regression is common.