Acetic Acid Wash for Unsatisfactory Pap Tests: A Quality Assurance Reassessment

Summary: Introduction: Acetic acid wash (AAW) for bloody and hypocellular Pap specimens has been used to improve adequacy rates; however, AAW leads to a delay in reporting, utilizes laboratory resources, and alters cytologic features. The impact of AAW on the turnaround time (TAT) and distribution of diagnoses at our institution was unclear. Given persistent staffing shortages in our cytology laboratory, we sought to re-evaluate the necessity of performing AAW. Materials and Methods: ThinPrep Pap tests processed during a 5-month period were retrospectively identified. The distribution of diagnoses and TAT for cases with and without AAW were compared. Cases were selected for AAW after review of an initial unsatisfactory slide. 15 mL of glacial acetic acid (GAA) solution (9 parts CytoLyt, 1 part GAA) was added to 5 mL of specimen, followed by vortex and centrifuge at 1500 rpm for 10 minutes. Supernatant was decanted, PreservCyt was added, and the sample was processed on the ThinPrep T-5000. Results: 8,806 Pap tests were processed during the 5-month period; AAW was performed on 424 cases (4.8%). The distribution of diagnoses is shown in Table 1. Performing AAW reduced the overall laboratory unsatisfactory rate from 6.7% to 3.3%. Although there was increased detection of endometrial cells in AAW cases, we did not see an increase in atypical glandular diagnoses in AAW cases. The TAT for AAW Pap tests with a NILM diagnosis was 9.0 days compared to 6.2 days for a NILM diagnosis without AAW Conclusions: AAW reduced Pap test unsatisfactory rate with minimal delay in TAT and no significant change in rates of atypical diagnoses.