Urethral bulking agents are one of the recommended treatment options in the guidelines for the management of stress urinary incontinence. There are many different injectable agents on the market, however, current evidence demonstrates a lower efficacy when comparing urethral bulking agents to mid-urethral slings. However, given the lower rate of complication following urethral bulking agents, its use in the management of stress urinary incontinence is rising.

The efficacy of urethral bulking agents in the treatment of stress urinary incontinence has been demonstrated across multiple studies, including comparative studies between mid-urethral slings and urethral bulking agents. So far these have demonstrated a high variation in the dry rate achieved. Studies have evaluated pre-operative factors that predict the need for MUS revision/removal, however, the pre-operative factors that relate to functional outcomes of urethral bulking agents are incompletely understood.

We undertook a review of the current literature to determine the level of evidence regarding factors predictive of functional outcomes following the use of urethral bulking agents.

A scoping review of the literature using PubMed was undertaken, including the search terms as detailed below. 

Our analysis included all available studies evaluating patient factors contributing to functional outcomes following the use of urethral bulking agents in the treatment of stress urinary incontinence. A systematic literature search was conducted using the PubMed database using the following search terms alone or in combination:
a)	“urethral bulking agent” AND
b)	“stress urinary incontinence” AND
c)	“outcome” OR “functional outcome” AND
d)	“pre-operative factors” OR “patient factors”.

Our literature search yielded three suitable papers for review, two of these studies were retrospective single-centre studies, and one a retrospective multicentric cohort study. Of these, the only statistically significant contributing pre-operative factors to functional outcomes were severity of urinary incontinence (measured using the 24-hour pad test) and Pdet max. However, there was no statistical significance found with regards to age or urethral hypermobility.

This scoping review has demonstrated that there is currently very limited evidence available with regards to factors that are predictive of functional outcomes following the use of urethral bulking agents.

The current literature base does not provide sufficient knowledge to determine factors predictive of functional outcomes following the use of urethral bulking agents. Therefore, more research is required in this area, so that patients can be appropriately counselled regarding their treatment options of their stress urinary incontinence. This will also allow for better patient selection for this procedure, thereby, aiming to improve patient outcomes and satisfaction.