Outcome of "Atypical squamous cells" in a cervical cytology screening program: implications for follow up in resource limited settings.

(1) To study the incidence and outcome of "Atypical squamous cells (ASC)" diagnosis in a hospital based cytology screening programme. (2) To work out a feasible strategy for follow up of Atypical squamous cells-undetermined significance (ASC-US) and Atypical squamous cells-cannot exclude high grade squamous intraepithelial lesion (ASC-H) in resource limited settings. A total of 29,475 women were screened cytologically through Pap tests. The epithelial cell abnormalities (ECA) detected on screening were reviewed by the cytopathologists and classified according to Bethesda 2001 system. The women with ASC-US reports were followed up by two repeat cytology tests at 3 and 6 months of the initial visit. The persistent ASC-US cases or the cases which revealed squamous intraepithelial lesion (SIL) on follow up smears; as well as all ASC-H and above cases were referred for coloposcopic evaluation. ASC diagnosis comprised 3.6% of all reports. These were qualified as ASC-US (3.36%) and ASC-H (0.22%). On follow up, only 7 CIN 2 or worse (3.2%) lesions were detected on 218 biopsies in ASC-US category while in ASC-H qualifier 16 CIN 2 and above lesions (30.8%) were picked up on 52 colposcopic biopsies. The difference between ASC-US and ASC-H categories for a CIN 2 or worse outcome was highly significant (P < 0.001). ASC-H qualifier has a high likelihood for an ominous histological outcome and warrants an immediate colposcopic evaluation. On the other hand, ASC-US cases can be managed conservatively by repeat cytology tests at regular intervals without a significant risk of missing a high grade lesion. Diligent screening of cervical smears can judiciously downgrade some cases overcalled as ASC because of inflammatory atypia and thereby reduce referrals in geographic settings with high prevalence of reproductive tract infections. High risk HPV (HR HPV) testing may be a useful adjunct to further reduce referrals by selecting the women who require colposcopic evaluation.