The presence of significant inflammation immediately post-BCG instillation can affect the accuracy of urine cytology. Urinary markers may be used to assess response to intravesical BCG therapy. In examining the change in UroVysion® FISH results before and after an induction or induction plus maintenance course of BCG, several studies have noted a correlation between response to BCG and likelihood of disease progression.133-137 Based on these studies, it appears that the presence of a persistently positive UroVysion® FISH following completion of induction BCG predicts a poor response to BCG therapy with a higher likelihood of recurrence and progression. Additionally, in patients who had a history of NMIBC, an observational study utilizing a novel scoring system based on UroVysion® FISH identified an association between a positive FISH and the development of MIBC.138 Based on these data, clinicians can use UroVysion® FISH as an early guide to predict response to intravesical BCG therapy. An additional test that could be used is Bladder EpiCheck®. One prospective cohort study of 65 patients demonstrated a positive Bladder EpiCheck® was associated with increased recurrence and BCG-unresponsiveness.139 However, a positive Bladder EpiCheck® does not currently have any evidence-based guidance on change of therapy and only has a 43% positive predictive value of BCG-unresponsiveness. Lastly, Computational Histology Artificial Intelligence (CHAI) can potentially be used to predict response to intravesical treatment; however, there currently is no evidence-based guidance for use of a specific alternative agent in this setting.140 The utility of protein-based markers in this setting has not been well-tested, but as with cytology, inflammation may also negatively impact their ability to predict response. Equivocal urine cytology can occur in as high as 21% of patients being evaluated for hematuria.141 Performance of a complete diagnostic work-up to rule out cancer is typically the default approach in many of these patients with atypical cytology readings and is one reason why its routine use is no longer advocated for hematuria evaluations. Even in patients with high-grade cancers, cytology may be read as suspicious or atypical.142, 143 Thus, utilization of another test to arbitrate an atypical or equivocal cytology reading may be helpful in reducing the need for unnecessary diagnostic evaluations in intermediate- and high-risk bladder cancer patients. While a smaller observational study suggests diagnostic accuracy of UroVysion® FISH to be inferior to urine cytology, studies have used UroVysion® FISH in this context, and found that these urine markers may help distinguish between patients with recurrence versus no recurrence.138 In more recent observational studies, Bladder Epicheck® had improved sensitivity but decreased specificity as compared to urine cytology, indicating potential utility in conjunction with cystoscopy for surveillance of recurrent disease.144-146 Some patients may present with a positive urinary marker while the bladder appears cystoscopically tumor-free. A proportion, but not all, of such patients subsequently develop cystoscopically-identifiable tumors. In these instances, the urinary marker is able to identify a tumor before it manifests, resulting in an “anticipatory positive” test. Among the newer markers, UroVysion® FISH has been found to yield an “anticipatory positive” test in approximately 30-40% of patients.147, 148 A recent study suggests that patients with atypical cytology and positive UroVysion® FISH may develop recurrent identifiable tumors earlier than patients with a negative UroVysion® FISH.149 In light of these data, these patients should continue close surveillance but do not all develop identifiable tumors.