The diagnosis of ASCUS (atypical squamous cells of undetermined significance) was introduced in the 1988Bethesda System for reporting cervical/vaginal cytologic findings. Outcome and appropriate management of patients with this diagnosis is not presently established. Criteria defining ASCUS are nuclear enlargement (2.5-3.0 times normal intermediate cell nucleus), mild nuclear hyperchromasia, smooth nuclear outlines with mild variation in nuclear size and shape, or else two, but not all three, cytologic criteria for human papilloma virus (HPV) cytopathic effect. All 668 cases reported as ASCUS from February 1992-December 1993 from our cytology laboratory were reviewed. These ASCUS cases represented 4.5% of all gynecologic cases diagnosed in that same time period. Of these, 284 (41%) had a subsequent colposcopic biopsy and/or endocervical curettage. The biopsied cases included 101 (36%) with condylomata, 38 (13%) with cervical intraepithelial neoplasia (CIN) I, 17 (6%) with CIN II, and 9 (3%) with CIN III. No cases of carcinoma were detected. Of patients with a cytologic diagnosis of ASCUS and subsequent cervical biopsy, 49% had low-grade cervical intraepithelial neoplasia (LGSIL), either condyloma or CIN I. Nine percent had high-grade cervical intraepithelial neoplasia, either CIN II or CIN III. These findings indicate that ASCUS defines cytologically a group of patients who may have either a concurrent or subsequent development of a squamous intraepithelial lesion (SIL). This forms a high-risk group. The management of cases with a cytologic diagnosis of ASCUS should be at least as aggressive as that of LGSIL. Diagn.

Many women having cervicovaginal smears interpreted as atypical squamous cells of undetermined significance (ASCUS) ultimately prove to harbor squamous intraepithelial lesions (SIL). The question is whether rare cells diagnostic of SIL are present in so-called "atypical" smears, but simply go undetected. To test whether the PAPNET Cytological Screening System, an automated system, can detect the (assumed) presence of such cells, six reviewers independently evaluated PAPNET video images generated for 101 cases conventionally diagnosed as ASCUS. Using PAPNET-identified microscopic coordinates, selected cases were then manually reviewed and reclassified according to consensus opinion. Overall, 35 cases were reclassified as SIL (22 low grade; 13 high grade). Histologic correlations showed 37 of the 101 cases conventionally interpreted as ASCUS carried tissue diagnoses of SIL, (28 low grade; 8 high grade, 1 ungraded). Using PAPNET, 24 of the 37 (65%) corresponding smears were reclassified as SIL (15 low grades; 9 high grade).

A rapid prescreening or rapid rescreening method for quality assurance in cervical cytology has been used in Europe and in Canada but has not been accepted in the United States. The rapid prescreen method was tested in a cytology laboratory that serves an academic medical center with a high-risk population for cervical cancer. For a period of 3 months, a tray of 20 sequentially numbered Surepath™ liquid-based preparations, randomly selected from the cervical cytology daily workload, were each prescreened in a random fashion for 1 minute. Experienced cytotechnologists performed the rapid prescreen. Results were recorded as negative, further review needed, or epithelial cell abnormality, category specified. The 20 cervical cytology preparations were then replaced in their same position in the daily workload for routine screening performed by another cytotechnologist. Final interpretation was by a cytopathologist as requested or required by Clinical Laboratory Improvement Amendments of 1988. The rapid prescreen data was tabulated and compared with data for a similar time period using the laboratory's normal quality assurance program. Seven hundred and twelve cases underwent rapid prescreen. Six hundred and forty-two were interpreted as negative. Twenty-six cases were interpreted as low-grade squamous intraepithelial lesion (LGSIL) or higher. Forty-four cases were classified as needing further review. For the 642 negative cases by rapid prescreening, routine screening reported 537 as negative and 105 as either abnormal or needed cytopathologist review. The error rate for the rapid prescreen is 50 of 712 (7.0%); for LGSIL and above 19 of 712 (2.6%). Of the 105 abnormal cases or those submitted for cytopathologist review, 31 were interpreted as atypical squamous cells of undermined significance (ASCUS), 41 cases as reactive/repair, 17 as LGSIL, 4 as unsatisfactory, 1 as atypical squamous cells, cannot rule out high-grade squamous intraepithelial lesion (ASC-H), 8 as the presence of endometrial cells in a women aged >40, 1 as malignant melanoma, and 2 as within normal limits with the presence of Actinomyces. The laboratory's routine quality assurance program selects cases, 10% of initially interpreted negative cases plus any gynecologic cytology on patients with a prior abnormal cervical cytology, or history of cervical epithelial cell abnormality. This quality assurance program averages 29% of cases, 4,045 of a total of 13,767, in 2008. Thirty-seven (0.9%) cases were detected in this rescreen (ASCUS, 16 cases; LGSIL, 13 cases; 1 high-grade squamous intraepithelial lesion; 4 ASC-H; and 3 atypical glandular cells of undetermined significance). Eliminating ASCUS cases, eight significant cases were detected, with an error rate of 0.2%. In this cytology laboratory, the rapid prescreen did not prove as reliable as routine quality assurance program for cervical cytology cases.

The diagnosis of ASCUS (atypical squamous cells of undetermined significance) was introduced in the 1988 Bethesda System for reporting cervical/vaginal cytologic findings. Outcome and appropriate management of patients with this diagnosis is not presently established. Criteria defining ASCUS are nuclear enlargement (2.5–3.0 times normal intermediate cell nucleus), mild nuclear hyperchromasia, smooth nuclear outlines with mild variation in nuclear size and shape, or else two, but not all three, cytologic criteria for human papilloma virus (HPV) cytopathic effect. All 668 cases reported as ASCUS from February 1992–December 1993 from our cytology laboratory were reviewed. These ASCUS cases represented 4.5% of all gynecologic cases diagnosed in that same time period. Of these, 284 (41%) had a subsequent colposcopic biopsy and/or endocervical curettage. The biopsied cases included 101 (36%) with condylomata, 38 (13%) with cervical intraepithelial neoplasia (CIN) I, 17 (6%) with CIN II, and 9 (3%) with CIN III. No cases of carcinoma were detected. Of patients with a cytologic diagnosis of ASCUS and subsequent cervical biopsy, 49% had low‐grade cervical intraepithelial neoplasia (LGSIL), either condyloma or CIN I. Nine percent had high‐grade cervical intraepithelial neoplasia, either CIN II or CIN III. These findings indicate that ASCUS defines cytologically a group of patients who may have either a concurrent or subsequent development of a squamous intraepithelial lesion (SIL). This forms a high‐risk group. The management of cases with a cytologic diagnosis of ASCUS should be at least as aggressive as that of LGSIL. Diagn. Cytopathol. 16:1–7, 1997. © 1997 Wiley‐Liss, Inc.

A statistically significant difference of the risk of developing SIL exists between patients with a negative smear versus those with an ASCUS smear. Long term follow-up is essential in the management of the patients with an ASCUS smear because there is clearly an increased risk of developing SIL.