Collagen injections are sometimes used to treat urinary stress incontinence, which is leakage caused by laughing and other activities that increase abdominal pressure. The injections are appropriate only if the muscle that controls urine flow (the sphincter) is weak and the pelvic floor muscles, which support the bladder and other urinary structures, are strong. This situation is usually a complication of surgery. In women, the causative procedure often is bladder neck suspension for stress incontinence. In men, it may be prostate removal, radiation for prostate cancer, or transurethral resection of the prostate (TURP) for prostate enlargement. Collagen is a fibrous tissue that, when injected into the urinary sphincter, adds bulk and creates a more secure seal.