Why is it people get multiple rounds for a BBL?

About 75% of my practice is revision surgery on patients who were operated on by other PSs. It is of paramount importance that the patient follow postoperative instructions to the letter and that the compression garment is worn as instructed. A less than desirable result may occur when a patient develops massive fluid collections postoperatively or repeated small fluid collections, which will cause a wavy nature to the skin or wrinkles in the skin. When the proper postoperative regimen is followed, the risk for contour irregularity is exceedingly small.
Contour deformities after liposuction are uncommmon and can be somewhat unpredictable as scarring is uniquely individual. Having the BBL done a second time is an option as long as the patient has enough fat to be transferred.  The revision implies that there is less fat than the first time, and scar tissue will make the surgery much more difficult on the surgeon.  The percentage of fat survival in the BBL the second time should be about the same.  About 50% of the fat that is transferred lives and becomes a part of you.  This will hold stable as long as there is no weight fluctuation.

Dear csanchez0,
generally speaking, 30-50% of transferred fat is lost after surgery and some patients get multiple rounds of fat transfer in order to get a significant increase in size. If you are considering a surgery, I would suggest you to consult a board-certified plastic surgeon. Only after a thorough examination you will get more information and recommendations.
Daniel Barrett, MD
Certified, American Board of Plastic Surgery
Member, American Society of Plastic Surgery
Member, American Society of Aesthetic Plastic Surgery

You are still a candidate for a BBL! High definition VASER liposuction allows the PS to harvest more fat from smaller areas. This fat is also more viable than fat harvested using traditional techniques. If you are a good candidate for a Brazilian Butt Lift (BBL), the optimal outcomes are achieved with: 1) use of VASER liposuction to harvest the fat, 2) a closed looped system such as Puregraft to process the fat, and 3) strategic micro-packet transplant technique. These three processes have demonstrated over 95% fat graft take. This means that your results will be stable as long as you maintain your weight. As an official VASER trainer, I am routinely referred unhappy BBL patients. One of the most common reasons for disgruntled BBL patients is that patients are not able to accurately communicate their desired buttocks goals to their surgeons.  A buttocks assessment tool can be an invaluable tool to communicate to your surgeon the exact buttocks size and shape you are desiring. A Skype or FaceTime consultation with a BBL specialist can help you get an accurate recommendation and pricing. 
Respectfully,
Arian Mowlavi MD,FACS
Realself 100 Hall of Fame Inductee