Nonionic versus ionic contrast media in intravenous urography: clinical trial in 1,000 consecutive patients

A double-blind clinical trial was performed in 1,000 consecutive patients to compare the safety and efficacy of intravenously administered nonionic (iohexol) and ionic (metrizoate) urographic contrast media. The patients ranged in age from 10 to 80 years. The incidence of mild to moderate adverse effects was 7.7% with iohexol and 31.2% with metrizoate. No serious reactions were recorded with either of the contrast media. Urography with iohexol was found to give better parenchymal opacification, pelvocalyceal opacification, and overall quality. The sum of examinations with good and excellent overall quality was 97.8% with iohexol and 91.1% with metrizoate. The frequency of poor overall quality urograms was 1.6% with iohexol and 7.5% with metrizoate. The data suggest that iohexol is safer and more frequently produces urograms of better quality.