Microscopic examination of exfoliated cells in the urine.
Ideally performed on a mid morning sample, or not the first void after waking, and ideally the whole voided urine (mid stream may be acellular).
- EAU – at least 25 mL, morning urine not suitable because of cytolysis
3 x specimens on different days increases the sensitivity.
Not sensitive for high grade disease – only 10 %. However, quite sensitive for CIS.
- Sensitivity 30 – 60 %
- Specificity 90 + %
i.e, positive cytology is concerning for likely tumour in urinary tract, whilst negative cytology does not rule out cancer.
Should be reported using Paris criteria:
High grade urothelial carcinoma:
- Nuclear:cytoplasm ratio > 0.7
- Nuclear hyperchromasia
- Irregular nuclear membrane
- Coarse chromatin
- At least 5 cells
Suspicious
- At least 1 cell with cytological changes (N:C ratio > 0.7, hyperchromasia, irregular nuclear membrane, coarse chromatin) but less than 5 cells
Atypical
- N:C ratio > 0.5, with one of the cytological changes
- No other reason for atypia
Low grade
- Fibrovascular cores or tissue fragments from a papillary lesion required – rare
Non diagnostic / unsatisfactory
Other malignancy
Negative – no abnormal cells
Causes of atypical urine cytology – calculi, infection, instrumentation, inflammation, chemo/radiation.
Positive cytology without bladder tumour
- Upper tract assessment – CT IVP / RPGs, ureteric washings +/- ureteropyeloscopy
- Random bladder biopsies
- Prostatic urethral sampling
10 % of CIS not well seen on white light cystoscopy.
If all negative? Ongoing surveillance – many will end up developing detectable urothelial carcinoma.
EAU recommend mapping biopsies at trigone, dome, right, left, anterior and posterior bladder wall (+/- enhanced cystoscopy).
Prostatic urethral biopsy – use resection loop between 5 and 7 o’clock.