Direct Smear Versus Liquid-Based Cytology in the Diagnosis of Bladder Lesions

Urine cytology is an important diagnostic method for urinary tract cancers (especially carcinomas), which is suitable for follow-up of residual urothelial tumors after surgery of malignant bladder tumors. Liquid-based cytology (LBC) was used for the first time in cervical cytology Compared to direct smear cytology (DSC), LBC reduced background elements (including cellular debris, inflammatory cells, and blood cells), provided better cell preservation, and had a higher satisfaction rate. In this study, we performed two different methods (DSC and LBC) to detect bladder lesions; also, we determined the sensitivity and specificity of these methods.

A total of 146 samples were taken from patients with suspected bladder cancer and processed for direct smear and LBC. In both methods, findings were reported according to the Paris System. Then, patients underwent cystoscopy and biopsy. Next, the accuracy of cytology methods was evaluated according to biopsy reports. The sensitivity and specificity of these methods were also calculated.

Credit indices obtained for the direct smear method included sensitivity (62.5%), specificity (89%), positive predictive value (89.5%), and negative predictive value (91.5%). For LBC methods, credit indices included sensitivity (85.7%), specificity (99%), positive predictive value (96%), and negative predictive value (96%). Agreement between the two methods was statistically significant (P<0.000) in negative biopsies but not in positive biopsies (P>0.05).

This study showed that LBC has higher sensitivity and specificity than the direct smear.