Is it safe to use an 18 gauge syringe to inject fat for BBL?

With the risk of fat emboli, there is no need to use a sharp needle for fat transfer when a blunt atraumatic cannula can be used instead (with more safety and equal control).Fat embolus is a very serious and known complication of fat transfer (which has been recently and tragically spotlighted in the media). While it is true, injection of donor fat into the infra-muscular plane (within the muscle) increases fat viability this does come with a significant increase in risk. There are large vessels deep to and within the muscle which can be inadvertently injected while grafting leading to a fat embolus. The consequences of such a complication are very serious and life threatening.
At the recent American Society of Plastic Surgeons Hot Topics, data from AAAASF (ambulatory surgical certifying body) was presented, suggesting that BBL/gluteal lipoaugmentation demonstrates a dramatically higher risk profile than other surgeries. The Aesthetic Surgery and Educational and Research Fund is convening a task force as well. The hope is that we will have more concrete guidelines for addressing these very serious complications.
That being said, the safest way to avoid fat emboli is to stay in the subcutaneous plane (at the expense of fat viability)and avoid the deeper muscular plane. If grafting of the deep plane is planned, surgeons should consider blunt cannulas, aspiration prior to injection. Using a supra-gluteal approach to minimize the risk of inadvertent intravascular injection has also been proposed.I would recommend discussing your concerns with your board certified plastic surgeon (ABPS).

Thank you for your question. I would make sure that you consult with a board certified plastic surgeon who is experienced in day transfer and BBL procedures. The standard for large volume fat transfer into an area such as the butt is to use a large 3-4 mm blunt tip cannula. The reason is two fold. One, the blunt tip cannula prevent trauma to the deep large vessels and avoids or minimizes the possibility of injecting fat in the vessels that would result in a fat embolus that could be leathal. Second, the larger bore cannula provides less resistance and pressure put on the fat cells resulting in less trauma to the cells and an over higher graft take rate. I would be very cautious of a surgeon who says he or she is going to do a larger volume fat transfer to the buttocks with a sharp 18 gauge needle or even a blunt 18gauge needle. Keep asking questions to make sure that you are fully informed and are confident in your plastic surgeons ability. Good luck. 

Typically larger cannulas (e.g. 5mm), not needles, are used for fat transfer. Be sure to consult with a board-certified plastic surgeon to gain insight.