Asymptomatic microhematuria (AMH) can be an indication of urinary tract cancer. Several international guidelines address algorithms for the evaluation of AMH found through routine dipstick testing [1, 2]. Especially in women with AMH, critics regard extensive diagnostic work-up including imaging as having too little specificity [3]. The aim of this study was to determine the (predictive) value of AMH a risk factor for urinary tract cancer, specifically in women attending an urogynecologic outpatient unit.

All patients who visited our urogynecologic outpatient clinic between April 2013 and March2023 were included. Demographic and clinical data including the dipstick results of all catheterized urine samples were extracted from the patients´ electronic charts. The obtained dataset (n= 3324) was cross-referenced with the central Austrian Cancer Registry. We analyzed the correlation between AMH findings and urinary tract cancer diagnosis. We defined urinary tract cancer as cancer that involved one or more of the following organs: kidney, ureter, bladder, urethra (ICD-10 codes C64-68).

Of 3324 included patients, 267 were positive for AMH, 2014 were negative for AMH. Dipstick results were missing for 1043 patients. Data from the Austrian Cancer Registry revealed urinary tract cancer in 33 patients within 10 years after urinanalysis. The 33 cases of urinary tract cancer were: bladder cancer (ICD-C67) in 20 patients (61%), kidney cancer (ICD-C64) in 13 patients (39%). Three patients had multiple urinary tract cancer diagnoses. Of all identified cancer cases, 6 patients had AMH and 12 patients had an urinanalysis negative for hematuria. Thus, the incidence of any type of urinary tract cancer was 2.2% in urogynecologic patients with AMH (Table 1). Fisher's exact test yielded a p-value of 0.01331 at a significance level of 0.05%.The sensitivity of the presence of AMH in the urinanalysis of catherized specimens was 33, the specifity was 88.5 (Table 2).

Our urogynecologic patient population showed a high prevalence of AMH at 8% and a higher incidence of urinary tract cancer diagnoses at 1% (n=33) compared to the general population. Incidences recorded in this study differ from those reported in the general population as urogynecologic patients represent a special patient group. Frequency of urinary tract cancer diagnoses in the AMH group was higher (2.2% vs. 0.6%), which implies a correlation between a positive hematuria dipstick finding and the presence of urinary tract cancer. On the other hand, 261 of all 267 AMH patients (97.8%) did not have a urinary tract cancer diagnosis. Thus, screening all dipstick AMH findings does not appear to be appropriate. In addition, 12 of the 2014 patients without AMH were diagnosed with a urinary tract cancer. Relying on the urinanalysis in these patients would miss their malignancy. 
Strength of the study: first study on the value AMH as a predictor for urinary tract cancer in urogynecologic patients. Large sample size, urinanalysis was always done from catheterized specimens, and robust cancer incidence data from a national cancer registry, in which all cancers diagnosed and treated in Austria are registered (as required by law).
Limitations of the study: Incidence of cancer of the urinary tract in women is low. An even larger database would yield even exacter estimates. The predictive value of macrohematuria could not be evaluated.

Current guidelines for the work-up of microhematuria do not appear to be useful for urogynecologic patients. A specific prediction model and algorithm for the diagnostic work-up of urogynecologic patients with asymptomatic microhematuria could be useful in deciding which patients actually require further investigations.

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