When researching the approach known as “safe BBL” (ultrasound-guided fat transfer to the buttocks), you may wonder where the fat is placed as well as where it is taken from. BBL, short for Brazilian butt lift, is an operation that adjusts volume and shape by transferring your own fat tissue to your buttocks. We use real-time ultrasound, tracking the cannula’s position on a screen as we inject the fat. We place fat only in the subcutaneous layer, beneath the skin and above the muscle.
The shape of the buttocks seen from the outside and the layer through which the injection passes provide different information. We explain which boundary the ultrasound image shows, why we avoid the area beneath the muscle, and how donor areas relate to body contours. As you research the operation, you can also explore suitability criteria and the considerations for sitting, lying down, and wearing a compression garment afterward.
What does real-time ultrasound show during BBL?
During fat transfer, a cannula, a thin, tube-shaped surgical instrument, is advanced into the target areas beneath the skin. Its entry point is visible from the outside, but tissue boundaries need to be observed to establish which layer it occupies inside. We obtain these images during injection using real-time ultrasound. As the cannula moves, we can follow the position of its tip relative to the layer covering the muscle on the screen.
The ultrasound probe is the handheld device that obtains images from the skin’s surface. These images can show the subcutaneous tissue, the fascia (a connective tissue layer) over the muscle, and the cannula’s position. Real-time imaging means tracking the cannula’s location during the procedure. Marking the area where fat will be added during the examination and imaging the working layer during surgery are separate steps.
We use the term “safe BBL” for this ultrasound-guided approach. During your consultation, you can describe which part of your buttocks you would like to add volume to. During injection, we track the cannula’s position in the subcutaneous space as it reaches that area. In a Brazilian butt lift (BBL) plan, volume distribution and the tissue layer where fat will be placed are determined separately.
Why is fat placed only above the muscle?
We place fat above the muscle and avoid the deeper area because large blood vessels run beneath the muscle. The working area for injection is the tissue between the skin and the fascia covering the muscle. We do not inject fat into or beneath the muscle. The boundary we track with ultrasound guides us in keeping the fat transfer within this subcutaneous space.
“Above the muscle” refers to the subcutaneous region overlying the muscle. Placing fat within muscle tissue falls outside this definition. The subcutaneous layer in the buttocks may not have the same thickness at every point. Fullness visible from the outside therefore cannot, on its own, indicate the cannula’s depth inside.
The volume that can be added to the buttocks is also limited by the structure of the subcutaneous space. Having abundant fat in the abdomen or waist does not mean all of it can be transferred to the buttocks. Tissue in the donor area and the thickness and skin structure of the recipient area are assessed separately. The desired volume is considered in relation to this anatomical space where the fat will be placed.
When explaining the volume plan, we can show on a drawing which part will be filled out. A request involving the back of the buttocks requires a different distribution from one involving a hollow at the side. Although the target area changes, we keep the injection within the subcutaneous layer above the muscle.
Where can fat be taken from for BBL?
The abdomen, flanks, back, and thighs are among the areas from which fat can be taken. The area where fat is collected is called the donor area, and the buttocks receiving it are the recipient area. Fat thickness, distribution, and skin elasticity are considered when selecting a donor area. Previous liposuction may affect the choice through the location and amount of remaining fat.
During liposuction (fat removal by suction), we prepare the tissue collected from localized fat deposits for transfer. We then inject it into the areas previously identified in the buttocks. When relating the fat-removal markings to the intended buttock shape, we also take the donor area’s own contour into account. The extent of fat removal from the waist depends on tissue thickness there and its transition into neighboring areas.
The abdominal fat accessible through liposuction lies beneath the skin; fat inside the abdomen around the organs is outside the scope of this procedure. Fat distribution may also differ between the inner and outer thighs. Because the outer thigh borders the side of the buttocks, this transition is considered when marking the limits of fat removal. Removing all the fat from each donor area is not the aim.
The collected fat is prepared for injection by separating it from accompanying fluid and free oil. The material collected during liposuction therefore differs in composition from the tissue to be transferred. The volume to be injected into the buttocks cannot be calculated directly from the total material collected. Alongside the prepared fat, the recipient tissue in the buttocks also limits the transfer plan.
How does liposuction affect the buttock and waist contours?
The flanks, lower back, and transitions into the thighs also contribute to the appearance of the buttocks. Removing localized fat from the waist changes the curve between the waist and buttocks, while injecting fat into the buttocks adds volume there. We distinguish the locations of these two interventions on the drawing. You can also show whether the feature you would like to change is your waist width, the projection of your buttocks in profile, or their side contours.
VASER liposuction may be used during fat removal. In this method, we apply ultrasound energy to break up the fat tissue, then remove it with a cannula. The ultrasound used during BBL injection images the cannula and tissue layers. Ultrasound in the name of a fat-removal method does not describe the same process as imaging during injection.
Hip dips are the inward curves at the outer sides of the hips. Outer thigh fullness, often called saddlebags, is located at the upper outer thighs. Both features may be present in the same person, with a hollow that could receive fat and a full area from which fat could be removed in separate locations. Bone structure also contributes to the shape of these transitions, so fat volume alone cannot account for every contour.
If there is mild laxity in an area where fat will be removed, we can also explain the option of plasma skin tightening. This treatment applies controlled heat to the connective tissue beneath the skin with the aim of contracting collagen fibers. Plasma addresses a different need from the fat transfer that adds buttock volume. Extensive excess skin may instead bring lifting procedures that remove the extra skin into consideration.
Who may be suitable for ultrasound-guided BBL?
People seeking a change in buttock volume or shape who have enough fat in donor areas and are in suitable general health for surgery may be candidates for BBL. Very lean people may not have enough tissue for transfer. Even when the amount of fat is suitable, the subcutaneous space in the buttocks and skin elasticity are assessed separately. Expectations about appearance are considered in relation to the structure of these tissues.
A stable weight helps in planning around the existing fat distribution. If weight loss is still a goal, buttock volume and the amount of fat in donor areas may also change. An uncontrolled chronic illness or smoking may require surgery to be postponed. Cosmetic fat transfer is not performed during pregnancy.
The word lift in BBL can be confused with a buttock lift operation that removes excess skin. BBL adds volume through fat transfer, while a lift removes sagging skin and repositions tissue. If extensive excess skin remains on the buttocks after weight loss, the need for a lift is determined separately. Excess skin and volume loss in the same person may call for different procedures within one surgical plan.
If you have previously had injections or surgery in your buttocks, you can share the method used and the areas treated. Knowing where previous liposuction was performed also helps when choosing new donor areas. During the examination, we record the existing volume distribution on the right and left sides separately and mark the transfer areas accordingly.
Sitting, sleeping positions, and compression garments after BBL
After surgery, we ask you to avoid direct pressure on the buttocks where fat has been transferred. We provide the sitting cushion after the operation and show you how to position and use it. We explain its use in relation to the areas that received fat. Seeing a demonstration of where the support should sit helps you relate the advice to your own surgical plan.
A BBL sitting cushion supports the backs of the thighs to limit weight bearing directly on the buttocks. Its position is adjusted so that the buttocks receiving fat do not press against the seat. Placing support under the buttocks is different from supporting the thighs. The cushion’s shape and position should follow the surgical team’s demonstration.
Lying on the stomach or on a suitable side are positioning options used to avoid pressure on the buttocks. If fat has been placed at the side of the buttocks, whether lying on that side is appropriate is determined separately. An additional procedure, such as abdominal surgery, may also affect the lying position. Sleeping positions are therefore described according to where fat was placed and the full scope of the operation.
A compression garment is chosen to cover the areas where fat was removed without compressing the transfer areas in the buttocks. Its cut and the regions it touches are part of the choice, as well as its size. The sitting cushion distributes weight when seated, while the garment supports the surgical areas. Wearing the garment does not replace the advice on avoiding pressure while sitting or lying down.
Frequently asked questions
Is fat injected into the muscle during BBL?
No, we place fat only in the subcutaneous layer above the muscle. Because large blood vessels run beneath the muscle, we avoid the areas within and beneath it. We track the cannula’s position with real-time ultrasound during injection.
Is ultrasound used for the same purpose in VASER liposuction and BBL?
Ultrasound has different roles in these two applications. In VASER liposuction, its energy breaks up fat tissue; during BBL injection, ultrasound images the layer containing the cannula. Fat removal and fat injection are therefore explained as separate stages.
Can another area be used if I do not have enough fat around my waist?
The abdomen, back, or thighs may be considered as donor areas if their tissue structure is suitable. The choice depends on the amount of fat remaining in these areas and the properties of the overlying skin. If the total donor tissue is insufficient, fat transfer may not meet the desired increase in volume.
Does the clinic provide the BBL sitting cushion?
Yes, we provide the sitting cushion after surgery. We demonstrate how to use it to support the thighs without placing weight directly on the buttocks where fat has been transferred. Positioning advice takes the transfer areas into account.
Can everyone sleep on their side after BBL?
Whether side sleeping is suitable depends on which part of the buttocks received fat. Fat transfer at the side or an additional operation may change the choice of position. The areas to support and those to protect from pressure while lying down are described according to the surgical plan.
