Contrast media and pain in patients with acute ureteral stone obstruction. A comparative study with iohexol and metrizoate.

A randomized study was conducted in 43 patients who were in pain due to acute ureteral obstruction. Emergency urography was performed in all patients, using either a low osmolar non-ionic (iohexol) or a high osmolar ionic (metrizoate) contrast medium. Increase of pain following injection of contrast media was found in 56 percent of all patients. Increase of pain occurred with both contrast media without any difference between the degree of pain nor the number of patients who experienced an increase of pain. Delayed excretion was considered the only reliable indicator of the degree of obstruction in the present study. Nineteen (68%) of the 28 patients with a delayed excretion greater than 10 min experienced increased pain while the incidence of pain increase was significantly lower (33%) in patients without that sign of ureteral obstruction (p less than 0.05). The increase of pain was not associated with a simultaneous increase of the mean arterial blood pressure.