Stress urinary incontinence (SUI) has been treated surgically with the midurethral sling but in recent years, this option has come under scrutiny and the risk-benefit balance continues to be reviewed. The low-risk alternative for women with uncomplicated SUI is the bulking agent, which aims to achieve continence through coaptation of the urethra. Two classes of bulking agents can be identified: those made from solid microparticles in an absorbable liquid or gel carrier (particulate agents) and those comprising a homogenous gel (non-particulates) that resists absorption. Polydimethylsiloxane®, carbon-coated zirconium oxide®, calcium hydroxyapatite® and polyacrylate polyalcohol copolymer® are currently marketed particulate agents. With the exception of calcium hydroxyapatite, the particles are non-degradable. Each agent achieves its long-term bulking effect through reactive changes around the persisting particles while the carrier volume is lost. Bulkamid® is a non-particulate agent with the bulking effect resulting from the volume of gel injected. The lasting network of fine fibers formed by the host tissue anchors the gel in situ. Foreign-body granulomas, erosion and migration/material extrusion and loss of bulk have been observed in connection with the particle-based products. Bulkamid may be mechanistically less liable to these events; however, there are minimal data directly comparing the two types of bulking agent. The question of durability is inevitable based on their differing modes of action.
Keywords: bulking agents; non-particulate; particulate; safety; stress urinary incontinence.
© 2019 Chapple and Dmochowski.