Not all unsatisfactory ThinPrep® cervical Pap tests™ are unsatisfactory: Reprocessing improves the satisfactory and detection rates of ThinPrep® cervical cytology

Abstract

One of the merits of ThinPrep 1 (TP) liquid-based preparation in cervical cytology is the reduction of the unsatisfactory rate in comparison with conventional smears. 1-3 This is achieved by reducing the presence of obscuring hemorrhage, inflammation, lubricant, mucus and nonblood contaminant materials in the background, and by virtue of the rapid fixation that allows clear viewing of the cellular details. 1-3 However, certain technical problems, probably inherent within the TP technique, can lead to unexpected limitations with regards the final satisfactory rate, especially when handling bloody material from symptomatic women. 3 Hemorrhagic smears can lead to deceptively unsatisfactory material that on occasions can hide significant epithelial abnormalities. Attempts to overcome this drawback can be a beneficial and a relatively cost-effective measure. Reprocessing by glacial acetic acid (GAA) wash is one way to improve the satisfactory rate of TP Pap tests.We conducted a prospective study over a 2-year period to investigate the effectiveness of reprocessing of unsatisfactory TP Pap slides in improving the overall satisfactory rate. We also studied the ability of reprocessing to uncover significant epithelial abnormalities. We used the 2001 Bethesda System, which requires a minimum number of squamous cells of 5,000 for liquid-based cytology to be clearly visualized. 4 Therefore, TP Pap tests slides with squamous cells less than 5,000 cells or poorly visualized and obscured cells were considered unsatisfactory and they were reprocessed. The remaining, residual Pre-servCyt 1 vial contents were transferred into a centrifuge tube. The fluid was centrifuged at 3,000 rotations per minute for 5 minutes. The supernatant was decanted, leaving a pellet at the bottom. A volume of 27 ml of CytoLyt 1 solution and 3 ml of concentrated GAA were added to the tube, and the contents were resuspended by vigorous agitation and recentrifuged at 3,000 RPM for 5 minutes. A 5 ml of PreservCyt 1 solution was added to the pellet, homogenized, and then added to a new PreservCyt solution TP vial and the solution was homogenized by vigorous manual agitation. A new second TP Pap slide was prepared using ThinPrep 2000 machine with a new filter. The reprocessing took 45 minutes and together with 30 minutes for Pap stain, the total turnaround time was 75 minutes.The study covered 8,224 TP Pap tests. Of these, 336 (4.08%) cases showed unsatisfactory Pap tests. After reprocessing, 285 (84.8%) cases showed satisfactory second slides, while 51 (15.2%) cases remained unsatisfactory. The final unsatisfactory Pap tests were reduced to 51 (0.62%) with a reduction rate of 69.6% of the unsatisfactory Pap tests. Of the 285 postprocessing satisfactory cases, 31 (10.9%) cases showed additional significant epithelial abnormalities. Of these, 15 (58.06%) cases showed atypical squamous cells of undetermined significance (ASCUS), 5 (16.13%) showed low-grade squamous intraepithelial lesion (LSIL), 4 (12.9%) showed high-grade squamous intraepithelial lesion (HSIL...

Factors associated with reduced accuracy in Papanicolaou tests for patients with invasive cervical cancer

“…Several studies (although not all) have reported significant underlying lesions, including invasive carcinoma, in women with unsatisfactory Pap test results . By directly studying a relatively large population of patients with invasive cervical cancer, the results of the current study demonstrate that patients with cervical cancer have a significantly higher rate of unsatisfactory and limited‐quality Pap tests.…”

“…Several studies have reported improved results in bloody ThinPrep Pap tests by processing an aliquot with glacial acetic acid. Reprocessing unsatisfactory cytology specimens with glacial acetic acid can significantly reduce the unsatisfactory rate by 18.3% to 69.6% according to multiple studies . This method is primarily effective with macroscopically bloody samples, with limited effect reported in cases with interfering lubricant …”

“…False‐negative screening tests can potentially result in a delay in diagnosis and treatment for women with undiagnosed high‐risk lesions, including cervical intraepithelial neoplasia of type 3 (CIN3) or cancer. Earlier literature has documented adequacy limitations in cytology samples from women harboring cervical cancer . Although sampling errors can account for the false‐negative Pap tests in many cases, it is well known that necrotic debris, blood, and inflammation (ie, tumor diathesis) noted in the background of frankly malignant Pap tests can interfere with accurate interpretation by cytotechnologists and cytopathologists.…”

Effect of glacial acetic acid pre‐treatment of cervical liquid‐based cytology specimens on the molecular detection of human papillomavirus

“…Concerns about the compatibility of GAA treatment with HPV testing were further raised by AbdullGaffar and Kamal in 2010, noting the need to validate the process used before bloody specimens could be considered suitable for HPV testing. The data collected from completed questionnaires from the Scottish cytology laboratories further highlight the heterogeneity of the GAA protocols used to treat bloody specimens and the complexity of assessment of the impact of GAA treatment on HPV tests.…”

Factors contributing to high ThinPrep® Pap test unsatisfactory rates in an academic medical center laboratory

“…The authors hypothesized that excessive blood obstructed the membrane filter, competing for capture of epithelial cells, thus producing an unsatisfactory cellular yield on the slide. Over the last several years, studies have reported an increase in specimen adequacy and cervical abnormality detection rates on the reprocessing of cervical samples with glacial acetic acid. Unlike prior studies, our laboratory visually examines the ThinPrep® vials for the presence of blood prior to processing in order to increase cellular yields.…”