What is the purpose and follow-up procedure for urine cytology (urine for cytology) testing?

From the Guidelines

Urine cytology testing is primarily used to detect cancer cells in the urinary tract, particularly bladder cancer, and should be considered in patients with persistent microhematuria (MH) after a negative workup, especially those with irritative voiding symptoms or risk factors for carcinoma in situ 1. The test involves examining cells shed into the urine under a microscope to identify abnormal or cancerous cells. To perform this test, a patient provides a urine sample, typically a clean-catch midstream specimen or one collected during a cystoscopy procedure. After collection, the sample is sent to a laboratory where it's prepared on slides, stained, and examined by a cytopathologist.

Key Points to Consider

• Urine cytology is useful for detecting high-grade urothelial carcinomas but has lower sensitivity for low-grade tumors 1.
• The test is often used for surveillance in patients with a history of bladder cancer, typically performed every 3-6 months initially, with frequency decreasing over time if no recurrence is detected 1.
• Follow-up procedures depend on the results, with negative tests but persistent symptoms possibly leading to repeat testing, and atypical or suspicious cells requiring additional testing such as cystoscopy, imaging studies, or bladder biopsies 1.
• In patients with intermediate-risk disease, a negative cytology result can reliably re-stratify a patient into a low/negligible-risk category, with the post-test probability of cancer detection decreasing to 0.1%-0.4% 1.

Recommendations

• Consider urine cytology for patients with persistent MH after a negative workup, especially those with risk factors for carcinoma in situ 1.
• Use urine cytology as part of a comprehensive workup for bladder cancer, including history, physical examination, cystoscopic evaluation, and imaging studies 1.
• Repeat urine cytology and other evaluations as necessary based on patient risk factors and symptoms 1.

From the Research

Urine Cytology Purpose

• Urine cytology is a diagnostic tool used to detect urinary tract neoplasia, including bladder cancer 2.
• The test involves examining urine specimens for abnormal cells, which can indicate the presence of cancer or other conditions 2, 3.
• Urine cytology is particularly useful for monitoring high-risk patients and detecting cancers in the bladder, although its accuracy decreases for lesions in the ureter or renal pelvis 2.

Follow-up Procedure

• If urine cytology results are abnormal, further testing, such as cystoscopy or biopsy, may be necessary to confirm the diagnosis 4, 3.
• Cystoscopy is a more sensitive diagnostic tool than urine cytology, but urine cytology can be used as an additive diagnostic tool to cystoscopy 3.
• In cases where urine cytology results are discrepant with histologic findings, repeated testing or diagnostic delays may occur, although severe harm is rare 5.

Test Characteristics

• The sensitivity of urine cytology for detecting bladder cancer ranges from 38.0% to 78.3%, depending on the grade of the tumor and the number of samples taken 3.
• The specificity of urine cytology is generally high, ranging from 78.6% to 98.3% 3, 6.
• Urine cytology is not a good localizing technique, but it can aid in the diagnosis of infections and inflammatory diseases 2.

Clinical Applications

• Urine cytology is not recommended as a routine test for women with irritative voiding symptoms, as the yield is low and the risk of urothelial cancer is low in this population 6.
• The utility of urinary cytology in the initial evaluation of patients with hematuria may be minimal, due to the low prevalence of bladder cancer and the low sensitivity of the test 4.