Ponovni pregled brisov materničnega vratu: notranja kontrola kakovosti dela citološkega laboratorija

Efficient quality control is essential in a well-organized screening program for early detection of cervical precancerous lesions. Various Pap smear review procedures are used to improve the detection of high-grade lesions. In the Department of Cytopathology at the Institute of Oncology Ljubljana, Slovenia we re-screened 6,813 (12.6%) conventional Pap smears out of a total of 54,000 slides screened in 2006, 2007 and 2008. Random re-screening of the slides (both negative and atypical) was conducted as a component of the educational program for screeners. False negative rate (FNR) was calculated according to the formula: false negative cases / (false negative cases + true positive cases) X 100. Of 6,813 re-screened Pap smears, 302 (4.4%) were reclassified into different categories: 221 (3.2%) smears were reclassified from negative to reactive, 73 (1.1%) from normal to LGSIL, 7 (0.1%) from LGSIL to HGSIL and one cases (0.015%) was reclassified from negative to HGSIL (true false negative). Of 8 cases reclassified as HGSIL, 7 were histologically confirmed as CIN2 and CIN3, one was designated as CIN 1. In this study, FNR was 2.4% for LG atypias in squamous cells and 1.3% for HGSIL. In our laboratory, small number of personnel limits the potential for rapid re-screening of all negative smears. Therefore, random re-screening of smears during the screeners' educational program is an adequate policy for quality control.V dobro organiziranih presejalnih programih za odkrivanje predrakavih sprememb na vratu maternice je nujna dobra kontrola kakovosti. Pri odkrivanju patoloških sprememb visoke stopnje laboratoriji uporabljajo različne načine ponovnega pregleda brisov materničnega vratu (BMV). Na Oddelku za citopatologijo Onkološkega inštituta v Ljubljani izvajamo notranjo kontrolo kakovosti od leta 2006 dalje v okviru šole za presejalce. V triletnem obdobju od 2006 do 2008 smo od januarja do julija pregledali 54.000 BMV, kandidati šole pa so znova pregledali 6813 (12,6 %) BMV. Napačno negativno stopnjo (NNS) smo računali po formuli: napačno negativni primeri / (napačno negativni primeri + PIL VS) krat 100. Ob ponovnem pregledu smo 302 od 6813 (4,4 %) BMV razvrstili v višjo kategorijo. Iz skupine negativnih, tj. normalnih brisov (A), smo v negativne, tj. reaktivne (B), prerazporedili 221 (3,2 %) BMV. V 73 primerih (1,1 %) smo oceno iz negativnega spremenili v patološke spremembe nizke stopnje, v 7 primerih (0,1 %) pa smo ploščatocelične intraepitelijske lezije nizke stopnje (PIL NS) prerazporedili v ploščatocelične intraepitelijske lezije visoke stopnje (PIL VS). V 1 primeru (0,015 %) smo negativen BMV prekvalificirali v PIL VS (pravi napačno negativni BMV). Histopatološka preiskava je v 7 primerih potrdila CIN 2 in CIN 3, v 1 primeru pa je bila diagnoza CIN 1. NNS je v naši študiji za PIL NS 2,4 %, za PIL VS 1,3 %. Menimo, da bi morali tudi v Sloveniji uvesti obvezen ponovni pregled BMV v okviru notranje kontrole kakovosti dela. Kontrola kakovosti, ki smo jo uvedli v našem laboratoriju v okviru Šole za presejalce, je primerna in jo lahko zaradi pomanjkanja presejalcev še naprej uporabljamo