Factors influencing pre-injection aspiration for hyaluronic acid fillers: A systematic literature review and meta-analysis.

Pre-injection aspiration of hyaluronic acid filler is a well-recognized yet controversial safety technique. Many consider aspiration to be an important safety measure to prevent inadvertent intravascular filler injection. To assess factors influencing pre-injection aspiration by understanding the relationship between aspiration time and a range of product, needle, and procedural characteristics.