Evaluation of collection and preservation techniques for urinary cytology

To decrease cellular degeneration and promote standardization of methods, the optimal conditions for urinary cytology need to be established. In separate experiments under controlled conditions, dissociated malignant human and benign rat bladder cells were collected and suspended in urine supernate at pH 4.5, 6.0 and 8.0. One-half of each suspension was added to an equal volume of 50% methanol, and aliquots were than examined at 1/2, 2, 24 and 72 hours for preservation of nuclear and cytoplasmic morphology and staining reactions. Cytologic detail was better preserved at pH 4.5, with little difference between fixed and unfixed specimens. Cellular morphology progressively deteriorated with increasing pH and prolonged storage. Fixation after collection improve preservation in urine of pH greater than 4.5. The pH of the first voided morning urine can be lowered by the ingestion of 1 gm of vitamin C at bedtime, improving cellular preservation both before and after voiding. These methods, if widely adopted, will improve the preservation of urine samples and reduce the variations in collection and preservation of specimens at different institutions.