E-Mail karger@karger.com Gynecologic Cytopathology Acta Cytologica 2013;57:585–590 DOI: 10.1159/000353843 External Quality Control of Cervical Cytopathology: Interlaboratory Variability Cinara Zago Silveira Ázara Edna Joana Cláudio Manrique Nádja Lindany Alves de Souza Andryne Rego Rodrigues Suelene Brito do Nascimento Tavares Rita Goreti Amaral Unit for External Quality Control, School of Pharmacy, Federal University of Goiás, Goiânia, Brazil ization of diagnostic criteria, and enhance the accuracy of screening and improve the quality of cytopathology test re- sults, it is necessary to perform external quality control. © 2013 S. Karger AG, Basel Introduction The cervical cancer screening programs based on screening tests has proven its efficiency in many countries where such programs are organized and mortality rates have been reduced [1]. However, this screening test must present a good diagnostic accuracy [1, 2]. The screening tests show a high percentage of false negatives (FN), with a range of 2–62%. The main causes of the low sensitivity are related to mistakes during the collection of material, the examination of the smear or the interpretation of results [3–5]. Programs of quality con- trol in cytopathology are an alternative that attempts to minimize these mistakes [6, 7]. Internal quality control is a necessary tool in the rou- tine of laboratories in order to reduce mistakes in the assessment and interpretation of screening tests [8, 9]. However, the evaluation of the performance of different laboratories can only be achieved through external qual- ity control [10]. Key Words Quality control · Cytology · Cervical screening Abstract Objective: To compare the variability of screening tests held at laboratories with the Unit for External Quality Control (UEQC), checking the frequency of cases that were discor- dant, false-positive, false-negative, unsatisfactory or that had a delay in clinical management and diagnostic agreement. Materials and Methods: The study analyzed 10,053 screen- ing tests from January 2007 to December 2008, including all positive cases, all those that fall under unsatisfactory and at least 10% of negative screening tests. The magnitude of the agreement was analyzed using the kappa coefficient. Re- sults: Out of the 10,053 cases analyzed, 7.59% were consid- ered disagreeing, and it was estimated that 1.1% were false- negative. There was a delay in the clinical procedure regard- ing 2.44% cases. There were 2.82% of cases identified as false-positive and 1.24% as unsatisfactory. The diagnostic agreement was excellent (kappa = 0.81). The agreement of most laboratories concerning screening tests was classified as very good. The agreement of the sample adequacy was reasonable (kappa = 0.30) and the agreement regarding the representation of epithelia was considered excellent. Con- clusion: Most laboratories showed very good agreement; however, it is worthy of note that to establish the standard- Received: January 14, 2013 Accepted after revision: June 19, 2013 Published online: October 1, 2013 Correspondence to: Dr. Cinara Zago Silveira Ázara Avenida Engenheiro Eurico Viana, Quadra 1, Lotes 1/2/3 nº 30 Apartamento 1106, Bloco A, Residencial Spazzio Gran Ville Bairro Alto da Glória Goiânia, Goiás 74815-725 (Brazil) E-Mail cinarazago  @  hotmail.com © 2013 S. Karger AG, Basel 0001–5547/13/0576–0585$38.00/0 www.karger.com/acy