High- and low-osmolar contrast agents in urography: a comparison of the appearances with respect to pyelotubular opacification and renal length.

The incidence of pyelotubular opacification and the change in renal length during intravenous urography with iohexol (Omnipaque) was compared with sodium/meglumine diatrizoate (Urografin). Pyelotubular opacification was seen in 14 out of 29 urograms performed with iohexol compared with one out of 28 urograms performed with sodium/meglumine diatrizoate. This increased incidence is statistically significant and has not been previously documented. The increase in renal length following intravenous contrast medium was similar for both iohexol and sodium/meglumine diatrizoate. The significance of these findings with respect to the interpretation of urograms performed with iohexol is discussed.