Available evidence indicates that intra-urethral injection of bulking agents is safe and effective for the treatment of UI, especially in women, resulting from intrinsic sphincter deficiency. Appropriate candidates should have no improvement in incontinence with conservative measures. For collagen-based products, a pre-treatment skin test for collagen should be performed, and show no evidence of local hypersensitivity. Patients whose incontinence does not improve after 3 treatment sessions are considered treatment failures. Periurethral injections of bulking agents should be avoided in the following persons: previous pelvic radiation therapy (less likely to benefit); unstable or non-compliant bladder; patients with severe allergies manifested by a history of anaphylaxis, or history or presence of multiple severe allergies; patients with an acute condition involving cystitis, urethritis, or infection; patients undergoing or planning to undergo desensitization injections to meat products (for collagen products).