Injectable bulking agents to treat stress incontinence have been used safely for several years. Bulking agents are usually composed of collagen (bovine), synthetic materials, or material obtained from the patient (autologous).

Stress incontinence is often the result of a weakened sphincter muscle (intrinsic sphincter deficiency), allowing the sphicter to remain partially open at rest. When abdominal pressure exceeds urethral pressure, the patient will experience loss of urine involuntarily.

Candidates for treatment with bulking agents include women who suffer from stress incontinence as a result of sphincter deficiency and men who become incontinent after prostate surgery. The procedure does not improve urge or overflow incontinence. The intervention itself is simple and can be performed in the office or in a hospital. It takes approximately 30 minutes to complete the procedure, and a local or general anaesthetic may be used.

For some, the injection of a bulking agent around the urethra may result in a cure (25%), while others experience an improvement in symptoms (50%). The procedure works less well in men. In addition, the procedure may need to be repeated every few years, as collagen is broken down by the body, resulting in a return or worsening of symptoms.