How is BBL preformed without hitting veins in the gluteal muscles?

One can lower the risk of the injection into vessels by several ways.  First, avoiding injecting into deeper planes where these vessels lie is recommended for safety, but may mean less of the fat survives as a graft.  Using  larger instruments makes it less likely that they can puncture into an vessel.  And, constantly moving as one injects makes it less likely that one will inject any significant amount of fat into a vessel.  Even still, there always exists a risk.  However, I believe that employing the above methods, as well as using vasoconstricting solutions, makes these risks so rare as to be acceptable.  The reported cases of deficits with these kind of surgeries do not make any mention of the technique and measures the surgeon used to avoid this complication.  So, make sure your surgeon is certified by the American Board of plastic surgery and is performing a safe technique.Best of luck!

Dr. SubbioBoard-Certified Plastic Surgeon  Newtown Square/Philadelphia, PA

The risk will not be zero with any technique or instrument but superficial injections with larger blunt cannula will have the lowest risk. Tweet       

Fat embolus is a very serious and known complication of fat transfer (which has been recently 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.
As always, discuss your concerns with a board certified plastic surgeon (ABPS).