Postphlebographic thrombosis: a double-blind study with methylglucamine metrizoate and metrizamide

A double-blind, randomized study was conducted in 170 patients to compare the effects of two hypertonic contrast media in phlebography of the leg: one was ionic [methylglucamine metrizoate (Isopaque Cerebral, 280 mg I/mI)] and the other nonionic [metrizamide (Amipaque, 280 mg I/mI)]. Ninety patients who showed no venous thrombosis on phlebography were followed up for 6 days with the 125I-fibrinogen uptake test, and those with abnormal scans were referred for further phlebography. Eleven of the 42 patients in the Isopaque group (26%) demonstrated signs of fresh venous thrombosis, compared with only 2% (1/48) in the Amipaque group, a highly significant difference (p less than 0.001). Six patients in the Isopaque group (14%) demonstrated clinical signs of superficial thrombophlebitis, which was not seen in the Amipaque group. Anticoagulant therapy is effective in preventing contrast-induced thrombophlebitis.