From the Guidelines
Cytology of urine is a crucial diagnostic test for detecting bladder cancer and other urinary tract malignancies, and it should be used in conjunction with cystoscopy and other urinary biomarker tests for comprehensive evaluation of patients with hematuria or those being monitored for recurrent bladder cancer, as recommended by the most recent guidelines 1.
Importance of Urine Cytology
Urine cytology involves collecting a urine sample, preferably the first morning void or a random sample with adequate volume (30-50 mL), which is then preserved and processed for microscopic examination by a pathologist. For optimal results, three consecutive morning samples should be submitted. The procedure is non-invasive and requires minimal preparation, though patients should avoid excessive fluid intake before collection to prevent dilution of cellular material.
Diagnostic Accuracy
Urine cytology is particularly useful for detecting high-grade urothelial carcinomas but has lower sensitivity for low-grade tumors. Results are typically reported as negative, atypical, suspicious, or positive for malignancy. While positive findings are significant, negative results don't completely rule out cancer due to the test's limited sensitivity.
Clinical Recommendations
According to the American Urological Association (AUA) guidelines, urine cytology may be useful in patients with persistent microhematuria following a negative work-up or those with other risk factors for carcinoma in situ (e.g., irritative voiding symptoms, current or past tobacco use, chemical exposures) 1. However, the American College of Physicians recommends against obtaining urinary cytology or other urine-based molecular markers for bladder cancer detection in the initial evaluation of hematuria 1.
Key Considerations
- Urine cytology should be used in conjunction with cystoscopy and other urinary biomarker tests for comprehensive evaluation of patients with hematuria or those being monitored for recurrent bladder cancer.
- The test is non-invasive and requires minimal preparation.
- Patients should avoid excessive fluid intake before collection to prevent dilution of cellular material.
- Positive findings are significant, but negative results don't completely rule out cancer due to the test's limited sensitivity.
- The decision to incorporate cytology as part of the work-up is best made by the treating physician who has knowledge of the patient’s history, physical findings, and other clinical information.
From the Research
Cytology of Urine
- Urine cytology is a diagnostic tool used to evaluate patients with hematuria, but its utility in the initial evaluation of patients with microscopic hematuria may be minimal due to its low sensitivity in detecting bladder cancers 2.
- A study found that the number of hematuric patients harboring bladder cancer was small (7%), and cytology detected only a few cases of cancer, with subsequent cytologies not detecting any additional cancers 2.
- Urinary cytology is indispensable for the evaluation of gross hematuria and surveillance of patients with urothelial neoplasms, but guidelines for the evaluation of women with a positive cytology and normal urinary tract are lacking 3.
- Routine urine cytology has been found to have no role in hematuria investigations, as it is costly and of limited clinical value as a first-line investigation for all patients with hematuria 4.
- The use of urine microscopy and cytological examination for early detection of bladder cancer in patients with lower urinary tract symptoms has been found to be not useful due to the low prevalence of bladder cancer in this population 5.
- Hematuria, whether gross or microscopic, warrants a thorough history and physical to determine potential causes and assess risk factors for malignancy, with prompt urologic referral recommended for gross hematuria 6.