Background: According to guidelines, the primary diagnosis of bladder carcinoma is symptom oriented. This means that diagnostic testing is indicated for macrohaematuria, chronically recurrent microhaematuria and chronic bladder urgency. This study tests the suitability of three point of care (POC) test systems, UBC rapid, NMP22 BladderChek and BTA stat, available on the market, with respect to interference due to blood contamination in urine samples.
Materials and methods: Urine samples were obtained from voluntary asymptomatic individuals without a history of bladder cancer. A specimen negative in all test systems was selected for further study. This sample was treated with fresh heparinized blood in a 1:10 ratio and then titrated in a dilution series. All the urine samples and their consecutive test results were photographed and a urinalysis was performed on each sample.
Results: In none of the samples of the dilution series did UBC rapid or NMP22 BladderChek show a false-positive result due to blood contamination. In contrast, with the BTA stat testing system, false-positive results were obtained from all samples with macrohaematuria and with densities up to 150 erythrocytes/μl, indicating a suspected tumour, whereas the sample was actually proven to be tumour free.
Conclusion: For the primary diagnosis of bladder carcinoma, neither the UBC rapid nor the NMP22 BladderChek POC test systems are sensitive to the presence of blood in the urine, whereas BTA stat consistently yields false-positive results due to cross-reactivity to macrohaematuria and microhaematuria up to a density of 150 erythrocytes/μl, thus this system should not be employed for this examination.