Urine cytology

Specimen:

Urine: voided urine is the collection method of choice for screening for urological disease. 

Although satisfactory for microbiological examination, early morning urine specimens provide poor samples for cytologic examination. 

A mid-morning or random specimen is recommended with the sample being sent to the laboratory quickly for processing. 

Rapid transport to the laboratory is recommended. If a short delay is inevitable, the container may be placed in a refrigerator.

 For longer delays prompt fixation can be achieved by collection of 50-100 mL of urine into an equal amount of 50% alcohol. 

Sensitivity of urine cytology increases with the number of specimens examined. 

Ideally at least three mid-morning or random specimens should be submitted for examination.

Catheterised specimens: may be submitted if clinically indicated.

Because of cellular changes present in catheterised specimens it is essential that the clinician indicate the nature of the sample.

Bladder washings: if clinically indicated this method of collection may be superior to voided urine. Disadvantages are the same as for catheterised specimens. 

Again the laboratory must be informed of the method of specimen collection for accurate interpretation.

Brushings: a disposable or non-disposable brush may be introduced through a cystoscope. 

The sample is brushed directly onto slides which can be alcohol fixed or air-dried depending on the laboratory protocol.

Method:

Laboratory preparation methods vary and include cytocentrifugation, membrane filter preparations and monolayer preparations. 

Examined with Papanicolaou staining and microscopy.

Application:

Detection of inflammatory lesions including specific infections, urinary crystal and calculi disease, iatrogenic changes and neoplasms of the urinary tract. 

Clinical information is essential as instrumentation and the presence of urinary tract stones may result in cytologic changes that mimic malignancy.

Interpretation:

Presence of malignancy recorded.  Interpretation of low grade urothelial neoplasms may be problematic due to benign mimics and minimal nuclear change. 

In females interpretation may be limited by contamination of cells from the lower genital tract.

Reference:

Gray W and Kocjan G eds. Diagnostic Cytopathology.  3rd ed. 2010. Churchill Livingstone.