Bulking agents: a urogynecology perspective.

A bulking agent is a material injected into the wall of the urethra to improve urethral coaptation in women suffering from stress incontinence. The concept was initially described in the 1930s when sodium morrhuate and paraffin were used to augment urethral resistance. Sclerosing agents were also used for inducing permanent urethral scaring to improve urinary leakage. Eventually, collagen and autologous fat were found to be efficacious, and only collagen demonstrated proven safety and endured extensive testing, becoming the gold standard for injectable agents. Since then, multiple other products have been developed by the industry, each with its particular success rates and complications.