The "free" routine postcatheterization urogram: a cost/benefit analysis.

Postangiography urography has become routine procedure in most centers performing cardiac catheterization in children. We analyzed the x-radiation dosage and clinical yield of this procedure. Using lithium fluoride thermoluminescent dosimeters, radiation exposure to the abdomen and gonads was measured in 35 children during postangiography urography. Results of 334 consecutive routine postangiography cine-urograms were evaluated based on clinical significance and compared to previous reports on this subject. Average absorbed abdominal radiation dosage was 241 mR +/- 240 from cine-urography, 16 mR +/- 13 from fluoroscopy, and 107 mR +/- 111 from a single abdominal roentgenogram. Gonadal dosage averaged 8 mR and was uniformly less than 27 mR. Of 334 routine postangiography cineurograms, 282 (84%) were normal, 30 (9%) were technically inadequate, 12 (3%) had abnormalities that were clinically insignificant or were falsely "positive" and in 10 (3%), clinically significant urologic conditions were confirmed. Because of the low yield of clinically significant anomalies and the added radiation exposure, we no longer perform routine postangiography cine-urography in children. Following cardiac angiography, the upper renal collecting systems are examined fluoroscopically. If abnormalities are suspected or fluoroscopy is equivocal, a single abdominal roentgenogram is performed. Using this procedure, mean average absorbed abdominal radiation dose can be reduced from 241 mR to 30.5 mR.