Background. Colposcopy is a secondary screening test used after a cytological specimen is reported as abnormal. A negative or normal colposcopy is not an infrequent outcome, and clinicians need to be aware of the clinical value of a normal and satisfactory colposcopic assessment.
To address this problem, the underlying causes need to be fully understood. To this end, we have analyzed a retrospective dataset relating to new referrals to an urban colposcopy service.
Method. We have reviewed 1,927 consecutive new colposcopic attendances during a 4-year period (1996-2000). Of these cases, 1,589 (82.4%) had documented satisfactory colposcopy in that the whole transformation zone was identified, and any lesion seen within it was suitable for outpatient-directed biopsy. These cases form the basis of this dataset. Seven hundred seventy-one colposcopies were classified as normal (48%).
Results. The presenting smear was atypical squamous cells of undetermined significance (ASCUS) (41.3%), high-grade squamous intraepithelial lesion (HiSIL) (42.2%), low-grade squamous intraepithelial lesion (LoSIL) (13.1%), and unsatisfactory in 3.4%. One hundred five patients (13.6%) eventually underwent loop diathermy excision (loop electrocautery excision procedure). The indications to treat were as follows: a high-grade smear (N = 31; 29.5%), a colposcopic suspicion of any cervical intraepithelial neoplasia in the presence of any smear result (N = 35; 33%), or a persisting minor cytological abnormality (N = 39; 37%). Patients were treated either at their first visit if they had a high-grade smear or up to the 10th visit. Forty-eight (45%) of the treated patients had high-grade disease. No cases of invasive disease were recorded.
Conclusion. Normal colposcopy in the presence of a low-grade cervical smear is associated with a very low risk of having or developing high-grade disease. The negative predictive value of normal colposcopy is a valuable clinical utility and underpins the importance of appropriate colposcopic training and the development of competencies that enable the confident exclusion of dysplasia.