The determination of Papanicolaou smear adequacy using a semiquantitative method to evaluate cellularity

To examine the influence of sample cellularity and the presence of endocervical columnar cells on the detection of cervical dysplasia, Papanicolaou (Pap) smears taken from patients with biopsy-proven CIN II and III were analyzed retrospectively. Adequacy was semiquantitated by dividing each smear into 15 equal areas using a lined template and assigning an adequacy index (AI) of 0 to 15. The total false-negative (FN) rate was 15.8 percent, with 6.1% representing interpretive error and 9.7% representing sampling error. For FN slides truly lacking abnormal cells, the average AI was significantly lower than that of true positives (TP), even when endocervical columnar cells were present. The entire group was then blindly re-evaluated using a subjective application of the Bethesda System, classifying slides as satisfactory, less than optimal, and unsatisfactory. Although correlation of AI with the rapid Bethesda System categorization was imperfect, the exclusion of less than optimal and unsatisfactory smears also lowered the FN rate, but less effectively. An AI scoring technique, therefore, may be useful in the routine evaluation of Pap smear adequacy.