Hundreds of thousands of women around the world are paying big bucks — and taking big risks — to get plumper, perkier derrières.

More than 520,000 people elected to get some type of buttock augmentation, including what's known as the BBL, or Brazilian butt lift, in 2021.

That’s an astounding 40.5% increase over 2017, according to the International Society of Aesthetic Plastic Surgery.

Yet the BBL — a procedure that involves harvesting fat from other areas of the body and injecting it into the buttocks — has been shown to have the highest mortality rate of any other aesthetic surgery procedure. 

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In South Florida alone, 25 BBL-related deaths were reported between 2010 and 2022.

And in a study published in the Aesthetic Surgery Journal in 2017, researchers from the University of Miami Miller School of Medicine found that the risk of death from the BBL procedure was somewhere between one in 2,351 and one in 6,214.

Fox News Digital talked to a woman who had the procedure — which for her was safe and smooth, according to her descriptions.

A 24-year-old Pilates instructor from Glendale, Arizona, said she'd always been self-conscious about certain areas of her body — and decided to do something about it.

"I have always had ‘hip dips,’ and I was unhappy with the pouch that was starting to form on my tummy," Alexandra of Arizona (she asked that her last name be omitted) told Fox News Digital via email. 

"I wished I could just move the fat to my backside instead," she said.

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Once she decided to get a Brazilian butt lift, the traveled to San Francisco, California, for the procedure. There, Dr. Jonathan Kaplan, a board-certified plastic surgeon, performed her surgery. 

She said she was thrilled with the results. 

"I was never trying to get a big butt, really — it was mainly just about removing my fat and replacing it to fill out my curves a little more," she said. "I just wanted a fuller, more natural look."

It’s not entirely clear who pioneered the procedure or how it got its name. 

It’s been reported that a Brazilian plastic surgeon named Ivo Pitanguy was the first to perform it in the 1960s. 

However, Dr. Leonard Grossman, a New-York based plastic surgeon, told Fox News Digital that he has been credited with inventing the procedure. 

In 1996, Dr. Grossman performed the surgery on a TV show in 1996. The patient on the show was a Brazilian woman, so the segment was titled "Building the Brazilian butt."

Today, the surgery is widely referred to as the Brazilian butt lift — even by the American Board of Cosmetic Surgery.

Despite its name, the BBL isn’t actually a "lift." It’s a fat-grafting process where fat is removed from other areas via liposuction and injected into the buttocks. The end result is a rounder, fuller, perkier butt.

Depending on the individual patient’s anatomy and fat composition, the fat can be extracted from the abdomen, thighs, hips, lower back or other areas.

The BBL doesn’t use any artificial fillers or implants, just the body’s own natural fat. 

So why are BBLs so risky — and what should people know if they're considering a surgical boost to their bottoms? 

Dr. Alexander Zuriarrain, a quadruple board-certified plastic surgeon with Zuri Plastic Surgery in South Miami, Florida, said he's performed more than 2,000 Brazilian butt lifts and has never had a complication. 

He believes lack of training is to blame for many of the deaths.

"There is a lack of consensus on the specific techniques that should be employed when injecting fat into the buttock," Dr. Zuriarrain told Fox News Digital in an email. 

"This has led to a great deal of confusion among practitioners as well as fear in the public."

Dr. Grossman has also performed thousands of Brazilian butt lifts and said he's never had any issues. He agrees that the alarming number of deaths is due to inexperienced doctors performing BBLs without the proper training.

"Just because someone is board-certified doesn’t mean they’re an experienced plastic surgeon," he said in a discussion with Fox News Digital.

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Dr. Grossman claims to know of at least one surgery group in the state of New York that advertises having plastic surgeons on staff despite having had no formal training. Just last year, he said the group experienced at least three deaths related to BBL procedures. 

"They’re practicing on human beings, and that's where people are getting hurt and dying," he said.

Dr. Adam Rubinstein is chief of plastic surgery for Jackson North Medical Center in Miami, Florida. When it was reported that South Florida experienced 25 BBL-related deaths between 2010 and 2022, he and his colleagues did some investigating.

"We found that in nearly all of those cases, fat was placed into the muscle, leading to fat embolism, which caused the patients' deaths," he told Fox News Digital in an email. 

"It is now well-known that placing fat in the muscle is a very bad idea … It is no longer allowed in the state of Florida," he added.

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Dr. Rubinstein said there are large veins around the muscles of the buttocks that can be injured during a BBL if the fat injections are placed in those muscles. 

"If that happens, there’s a high risk of fat entering the injured veins and being carried by the bloodstream to the lungs, causing a fat embolism," he said. 

Pulmonary fat embolism is the leading cause of death during BBL procedures, studies show.

In 2017, the Aesthetic Surgery Education and Research Foundation (ASERF) sent an anonymous survey to 4,843 plastic surgeons worldwide to try to determine how often fat embolisms occurred. 

Around 7% of the surgeons who responded said they had seen at least one pulmonary fat embolism during their careers, with a total of 32 fatalities reported.

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In June 2021, the Florida Medical Association (FMA) announced in a press release on its website that intramuscular or submuscular fat injections were prohibited. 

The release also stated that "[w]hen performing gluteal fat grafting procedures, fat may only be injected into the subcutaneous space and must never cross the gluteal fascia." 

BBLs are more dangerous for some patients than others.

"Factors that make patients prone to complications with any surgery include a history of diabetes, hypertension, anemia, obesity and malnutrition," Dr. Samuel Lin, an associate professor of surgery at Harvard Medical School, told Fox News Digital.

Patients who smoke or drink excessively should stop doing so before surgery, said Dr. Lin. Those with chronic lung, heart or kidney disease also face a higher risk of complications, he warned.

Additionally, people who are significantly overweight or underweight probably aren’t good candidates for BBLs, Dr. Rubinstein said. 

"Being overweight greatly increases the risks of complications, including infection and wound healing problems," he said. 

"On the flip side, a very thin patient has less fat in the buttocks to begin with and could be at a higher risk for fat being accidentally placed into and around the muscles." 

Also, a very thin person may not have enough fat to transfer from other areas.

For those considering a BBL, it’s important they choose an experienced surgeon who is certified by the American Board of Plastic Surgery. 

"It’s not enough to ask a doctor if he or she is board certified," said Dr. Rubinstein. "You must look for the American Board of Plastic Surgery, since that is the only Board that certifies plastic surgeons. A doctor can be certified by the American Board of Pediatrics and still be offering BBL surgery services."

Additionally, Dr. Zuriarrain recommends choosing a surgeon who uses a wireless ultrasound device that helps ensure the injection doesn’t go too deep into the muscle, which is "a recipe for fat embolism and possible death."

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(The FMA now requires that Florida surgeons use ultrasound technology for buttock injections.)

Experts also say to steer clear of high-volume plastic surgery centers.

"You probably shouldn’t be the seventh operation your surgeon is performing that day," said Dr. Rubinstein. 

"The state of Florida has now limited the total number of operations a surgeon can perform in a day. More than three procedures in one day can be a lot for one doctor. Make sure you’re not getting a tired surgeon at the end of the day."

Dr. Rubinstein added that the best way to avoid a bad outcome is to make careful choices in procedures, surgeons and facilities.

"Do your homework like your life depends on it, because it just might," he said.