The aims of this study were to compare the cytomorphologic features diagnostic of atypical squamous cells (ASC) in liquid-based preparations (LBPs) and conventional Pap (CP) smears and to cytomorphologically assess the performance of the Cell Scan 1500™ in cervical cytology practice.

Cervicovaginal smears were obtained from 938 women. Two smears were obtained simultaneously from each individual, one for an LBP and the other for a CP smear; the smears were independently examined. ASC was diagnosed in 24 patients, and their samples were cytomorphologically and semiquantitatively analyzed.

A total of 24 of the 938 women (2.6%) were diagnosed with ASC by one or both methods. Results from LBPs and CP smears were in agreement in 13 of 24 cases of ASC diagnosis (absolute direct agreement, 54.2%; k<0.20; p-value from chi-square test=0.085). Diagnostic features of ASC in the LBPs included squamous cell atypia and atypical squamous metaplasia.

The cellular features diagnostic of ASC present in one preparation can manifest themselves differently in the other. Changes in individual cells, particularly nuclear changes, are the most reliable features for diagnosing ASC. The Cell Scan 1500™ processor is more effective at detecting ASC than are CP smears.

We have retrospectively assessed the incidence and outcome of women diagnosed during a hospital-based cytology screening program with "atypical squamous cells (ASC)" and followed-up with loop electrical excision procedure (LEEP).

We analyzed 173,947 cases of cervical smears' follow-up cytology and histology findings. Previous or archival cytology with LEEP results were retrieved for 390 women with ASC of undetermined significance (ASC-US) and 112 with ASC, cannot exclude high-grade squamous intraepithelial lesion (ASC-H).

On the follow-up cytology, of the 390 women initially diagnosed with ASC-US, 130 (33.3%) had no follow-up records of smears before LEEP; smears of 18 (4.6%) were negative for cytologic abnormalities, 193 (49.5%) were ASC-US, 24 (6.2%) were ASC-H, 111 (28.5%) were low grade squamous intraepithelial lesion (SIL), and 44 (11.4%) were high grade SIL. LEEP findings in these 390 women showed that 183 (46.9%) were negative, 73 (18.7%) were graded as cervical intraepithelial neoplasia (CIN) 1, 25 (6.4%) as CIN 2, 102 (26.2%) as CIN 3, and 7 (1.8%) had carcinoma. LEEP was performed in 112 women initially diagnosed with ASC-H; 36 (32.1%) were negative, 4 (3.6%) were graded as CIN 1, 7 (6.3%) as CIN 2, 60 (53.6%) as CIN 3, and 5 (4.5%) with carcinoma.

Patients with ASC-H smears were at increased risk of SIL or carcnoma compared with patients with ASC-US. Careful follow-up is required in ASC patients.