Fat embolism. I read it's 20 times more likely for BBL. What's the probability ? Causes? Avoidable? If it happens then?

Fat embolus is a very serious and known complication of fat transfer. The probability of embolus is much higher in the setting of fat transfer than for liposuction alone.A fat embolus occurs when injected fat is inadvertently introduced into a vessel and travels centrally within the vasculature. The hallmark triad of symptoms include neurologic changes, a petechial rash, and respiratory changes. The treatment is typically supportive in nature. While it is a very serious complication, if diagnosed early it can be managed. Mortality rates are quoted as low as 5%.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.

Great question.  There has been recent literature written about the increase incidence of fat embolism with BBL.  What causes this is that the gluteal tissue has a lot of blood supply and if fat is accidentally injected into the larger vessels, it creates an embolism.  Unfortunately these blood vessels cannot be seen, but the general anatomy and areas to avoid are somewhat known.  I don't know if there is any study that has shown a probability percentage but the incidence is low for a fat embolism that causes issues.  The biggest problem with fat embolism is respiratory distress - which is a medical emergency and would need to be hospitalized.  Very small embolisms usually do not cause an issue, but because they don't present with symptoms it is unknown how probable the true rate of fat embolisms are.Hope this information helps!- Dr. Roger Tsai   @DrRogerTsai