Liquid-based cytology is a commonly used method for cervical cancer screening but new evidence suggests that ThinPrep, a liquid-based test, is no more effective than conventional cytology.  In a cluster-randomized trial conducted in 246 clinics in the Netherlands, ThinPrep was compared to conventional cytology for cervical cancer screening in 89,784 women aged 30-60 years.  Though the liquid-based test resulted in fewer unsatisfactory results, there were no significant differences in the detection of abnormalities between the two tests in analyses performed at 2 independent laboratories (level 1 [likely reliable] evidence). For each test, the rate of atypical squamous cells of undetermined significance (ASCUS) was 2-4%, of low-grade squamous intraepithelial lesions (LSIL) about 1%, and of high-grade squamous intraepithelial lesions (HSIL) 0.5-0.8% (Obstet Gynecol 2008 Dec;112(6):1327).  These results are consistent with an earlier systematic review (Obstet Gynecol 2008 Jan;111(1):167) and an earlier randomized trial (BMJ 2007 Jul 7;335(7609):28).  Liquid-based cytology is more expensive than conventional cytology but it does provide the added ability to test for HPV (including reflexive testing of abnormal samples), gonorrhea and Chlamydia from the same sample.  Whether this benefit warrants the increased cost will depend on many factors that may vary across different practice environments.  For more information, see the Cervical cancer screening (including Pap smears) topic in DynaMed.