The effect of water soluble contrast material on urine cytology.

Urothelial cells were obtained from the pelvicalyceal system of ten patients by retrograde pyelography using a 60% solution of meglumine diatrizoate (Hypaque meglumine 60%, Winthrop Laboratories, New York, New York). The cells showed some cellular shrinkage, nuclear pyknosis, fragmentation, and occasionally cytoplasmic vacuolization. Cells from bladder urine obtained from 14 patients after an intravenous urogram using a 50% solution of sodium diatrizoate (Hypaque sodium 50%) showed no cytologic changes. In vitro exposure of bladder urothelial cells to 50%, 25% and 12.5% Hypaque sodium and 60%, 30% and 15% Hypaque meglumine as well as exposure of mesothelial cells to 50% Hypaque sodium resulted in the same cytologic changes as those seen when the urothelium was exposed in vivo to this material during retrograde pyelography. The mechanism for this effect, therefore, is by direct action of the contrast media on the cells and is concentration dependent. The cytopathologist should be aware of the changes induced by radiographic contrast materials such as Hypaque sodium or meglumine when interpreting urine cytology. This knowledge may be useful in preventing false positive diagnoses.