Storing partially used hyaluronic acid gel fillers after the initial patient injection carried a small risk of contamination, according to study results in Dermatologic Surgery.

“After tissue augmentation procedures, the remaining continent of filler syringes are commonly used for a retouch after a few weeks or for re-treatment, when the augmentation effect begins to subside after many months,” Mohammed Al-Haddab, MD, of the dermatology department at King Saud University, Riyadh, Saudi Arabia, and colleagues wrote.

The researchers studied patients injected with a portion of Juvéderm Ultra Plus (Allergan) or Restylane (Q-med), between 2009 and 2012 at a dermatology clinic.

The remaining hyaluronic acid from 36 syringes was stored at room temperature, with sterile procedures including exchanging the needle used for initial augmentation procedure with the original tip cap or with a new sterile needle to avoid microbial contamination.

The mean storage duration was 57.8 months, with in vitro testing for growth of microbes, including gram-positive and gram-negative bacteria, mycobacteria and fungi, for each syringe.

None of the syringes had any growth in the fungal and acid-fast bacilli cultural media. There were five positive bacterial cultures, which were predominantly contaminated with normal skin surface flora.

The researchers recommended using the fillers for deeper injections in the first session and discarding the remainder, since touch up procedures in deep injection are usually unnecessary.

Otherwise, “at a touch-up visit, we suggest squeezing out tiny drops of the [hyaluronic acid] (less than 0.05 mL) and changing to a new needle before commending the augmentation,” the researchers wrote. “The syringe should be discarded if the contents our cloudy.”