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Urine Cytology

Indications:

• Diagnosis of bladder cancer, urethral cancer or upper urinary tract cancer (in unclear cases).
• Follow-up of bladder cancer with an intermediate or high risk for recurrence or progression.
• Follow-up of upper urinary tract cancer.

Preparing the Specimen for Urine Cytology

Use fresh urine for cytology, morning urine is not suitable due to osmotic artifacts. An irrigation of the bladder or upper urinary tract with 5–20 ml NaCl is an alternative to voided urine. The urine or the irrigation fluid is centrifuged, the cells are fixed on a slide and stained (e.g., Papanicolaou's technique or quick staining techniques).

Normal urothelial cells are large (see adjacent leukocytes) and have a small round nucleus.

Urine cytology with a high-grade tumor cell: in comparison to the normal urine cytology, a reduction of the cytoplasm and an enlargement of the nucleus is seen. The nucleus is not round and of inhomogen staining.

Reporting:

Normal urothelial cells are large and contain a small round nucleus with fine homogenous chromatine [fig. normal urothelial cell]. Depending on the dedifferentiation of the urothelial cells, the nuclear-cytoplasmic ratio increases as the nucleus enlarges and the cells become smaller [fig. high-grade cancer cell]. In addition, the nucleus becomes irregular in regarding to form and chromatine, see table criteria for malignancy of urothelial cells. Urine cytology is observer-dependent. However, in experienced hands specificity exceeds 90% for the detection of high-grade tumor cells. Well-differentiated tumors are more difficult to identify, since fewer cells are shed and the differences between inflammation and well-differentiated tumors are not unequivocal.

The microscopic examination of exfoliated urothelial cells in voided urine can reliably identify G2 and G3 cells of urothelial carcinoma. Well-differentiated tumors are more difficult to identify, since fewer cells are shed and the differences between inflammation and well-differentiated tumors are not unequivocal.

References

  Deutsche Version: Urinzytologie