Urine cytology is a laboratory test that examines cells shed from the urinary tract to identify abnormalities. It helps healthcare providers detect unusual cells, which can indicate various conditions, including cancer, providing valuable information about urinary system health.
Defining Urine Cytology
Urine cytology involves the microscopic examination of cells in a urine sample. Cells naturally shed from the urinary tract lining (kidneys, ureters, bladder, urethra). A cytopathologist analyzes the prepared sample under a microscope, identifying cellular changes suggesting inflammation, infection, precancerous conditions, or cancer. While a helpful screening method, it is generally used with other tests for a definitive diagnosis.
Reasons for a Urine Cytology
Urine cytology is often ordered to investigate unexplained blood in the urine (hematuria). This includes visible and microscopic blood, as hematuria can signal urinary tract conditions, including cancer. It also monitors patients with a history of bladder or other urinary tract cancers for recurrence. It may also be used for persistent urinary symptoms like painful, burning, or frequent urination when infection is not the cause.
How a Urine Cytology is Performed
Urine sample collection typically uses a “clean catch” midstream method. This involves cleaning the genital area, starting urination into the toilet, then collecting a portion into a sterile container. This minimizes contamination. Avoid collecting the first morning urine, as cells can degrade overnight.
The collected sample is sent to a laboratory for processing. Lab technicians use a centrifuge to separate and concentrate cells. This material is prepared on slides and stained with special dyes, making cells and abnormalities visible for the cytopathologist.
Interpreting Urine Cytology Results
Urine cytology results categorize abnormal cells. A “negative” or “benign” result means no abnormal cells were found, suggesting normal cellular appearance.
An “atypical” result indicates cell changes not clearly normal or cancerous, possibly due to inflammation, infection, or other non-cancerous conditions. A “suspicious” finding suggests malignancy but is not conclusive for cancer. A “positive” or “malignant” result signifies cancerous cells, strongly suggesting urinary tract cancer. The Paris System provides standardized categories, focusing on high-grade urothelial carcinoma.
Understanding Limitations and Next Steps
Urine cytology has limitations, particularly its sensitivity in detecting low-grade tumors, which may not shed cells or show clear abnormalities. This can lead to false negatives, where cancer is present but undetected. Conversely, false positives can occur, indicating abnormal but non-cancerous cells, possibly due to inflammation or infection. The test’s accuracy is higher for detecting high-grade tumors.
Given these limitations, urine cytology is often part of a broader diagnostic workup. If results are atypical, suspicious, or positive, further investigations are recommended. These may include repeat cytology, imaging (e.g., CT scans), or cystoscopy (a thin tube with a camera to visually inspect the bladder lining). A biopsy may also be performed for a definitive diagnosis.