Buttock Augmentation Using Doppler Ultrasound-guided Cannulation for Patient Safety

Abstract

Background:

Augmentation gluteoplasty performed through autologous fat grafting is a surgical technique that volumizes the buttock and shapes the gluteal region according to the patient’s expectations, but it is one of the most dangerous aesthetic surgical procedures due to the high rate of the complication and mortality. The aim of the study was to assess the safety of subcutaneous gluteal fat grafting using ultrasound-guided cannulation.

Methods:

A retrospective study of the clinical outcomes of gluteal augmentation with Doppler ultrasound-assisted fat grafting was conducted. The medical records of 177 patients who underwent gluteal augmentation between February and May 2024 were analyzed.

Results:

In a sample of 177 patients who received gluteal fat grafting, we found that the visualization of perforating arteries had a median of 9 arteries (interquartile range: 2) per buttock. Distribution by quadrants varied among patients. The use of Doppler ultrasound-guided fat grafting was shown to be safe; related complications included 5 patients with hematomas, 2 with seromas, and 1 with suture dehiscence; no cases of infection, deep vein thrombosis, pulmonary embolism, or death were reported.

Conclusions:

Subcutaneous gluteal lipoinjection with Doppler ultrasound indirect vision is a procedure that meets patient safety standards. It allows visualization of the tissue where the fat is grafted, reducing the risk of developing thrombotic events by identifying risk structures such as the intramuscular plane and vascular structures. Achieving a good aesthetic result and a low complication rate requires prior training in the use of ultrasound specifically for gluteal lipoinjection using Doppler.

Takeaways

Question: Is Doppler ultrasound assistance essential to reduce complications and mortality in buttock fat grafting?

Findings: Each buttock contains a high number of perforating arteries, with a median of 9 arteries per side (interquartile range: 2). Their distribution varies between quadrants and is not consistent across patients.

Meaning: There is no universally safe zone for fat grafting without the aid of ultrasound. Ultrasound imaging enables precise identification of gluteal anatomical layers, whereas Doppler ultrasound allows for localization of perforating vessels. Together, they represent the safest approach to performing gluteal fat grafting.

INTRODUCTION

Gluteal augmentation using autologous fat grafting is a surgical technique that enhances the buttocks by volumizing and shaping the gluteal region according to the patient’s expectations.¹ Buttock augmentation ranks as the seventh most common plastic surgical procedure globally, with more than 820,760 procedures performed in 2022, particularly prevalent in South American and Asian countries.²

Despite its popularity, gluteal fat grafting has been associated with various complications such as surgical site infection, seroma, wound dehiscence, hematomas, and soft tissue necrosis.³ However, none are as concerning as the increased reports of mortality due to fat embolism related to gluteal fat grafting over the last decade, with numerous deaths reported in Mexico, Colombia, and Florida.⁴ The Aesthetic Surgery Education and Research Foundation estimates the occurrence of fat embolism at approximately 0.06% during this procedure.⁵

The mortality linked to buttock augmentation via autologous fat grafting is primarily attributed to fat injections at the intermuscular level,^3–5 which increases the risk of both micro fat embolism (MIFE) and macro fat embolism (MAFE).⁶ MIFE arises from microtraumas to vessels that release small fat particles into the bloodstream, eventually lodging in the lungs and disrupting the alveolar–capillary interface. Clinical symptoms manifest 24–48 hours postoperatively, with a mortality rate of approximately 30%, depending on the timeliness of intervention. Conversely, MAFE involves larger fat emboli that block blood vessels in the lungs, causing immediate clinical manifestations and a mortality rate exceeding 95%.⁶

Given these risks, plastic surgery associations have issued guidelines to enhance the safety of the procedure. These include mandating that only certified plastic surgeons trained in the technique should perform the procedure, that it be guided by ultrasound, and that pre- and postoperative counseling be provided.⁷ However, a recent survey revealed that more than half of surgeons do not use ultrasound, citing it as unnecessary and relying on their experience instead.⁸

In contrast, there is a growing trend in favor of patient safety, with many surgeons now adopting ultrasound guidance during these procedures. This approach has led to better aesthetic outcomes, fewer complications, and no reported fatalities.^9–11 The aim of the current study was to assess the safety and efficacy of subcutaneous gluteal fat grafting using Doppler ultrasound-guided cannulation.

METHODS

Study Design

A retrospective analysis was conducted on the clinical outcomes of gluteal augmentation performed using Doppler ultrasound-guided fat grafting. Medical records from 177 patients who underwent the procedure between February and May 2024 were reviewed. The data collected included information on surgical interventions, medical history, liposuction volumes, fat grafting volumes, safety measures, and recorded complications.

Subjects

The study involved medical records from 4 surgeons based in Bogotá, Colombia. The participants were all patients between 19 and 60 years of age who underwent subcutaneous gluteal fat grafting with ultrasound guidance. Patients were excluded if they declined to participate or if their medical records were incomplete. All patients gave informed consent to participate in the study.

Procedure

Following liposuction, the limits of the gluteal region were marked (superior: iliac crest line; inferior: subgluteal fold line; medial: intergluteal line; lateral: projection of the posterior axillary line). A perpendicular line was drawn from the midpoint of the superior line to the midpoint of the inferior line, and from the medial to the lateral line, dividing the buttock into 4 quadrants (superior lateral, superior medial, inferior lateral, and inferior medial). (See Video 1 [online], which displays gluteal region marking for fat grafting.)

Video 1. This video displays gluteal region marking for fat grafting.

Download video file ^{(52.4MB, mp4)}

Doppler ultrasound was then used to explore the gluteal layers in real time, searching for perforating arteries at the subcutaneous level. Any blood vessels detected were marked on the skin to guide the fat grafting process. (See Video 2 [online], which displays Doppler ultrasound exploration per each gluteal quadrant.)

Video 2. This video displays the Doppler ultrasound exploration per each gluteal quadrant.

Download video file ^{(1.8MB, mp4)}

Gluteal fat grafting was performed manually using syringes while the patient was in the prone position. After decanting, fat was injected retrogradely using a 4-mm cannula. The surgeon visualized the cannula in the subcutaneous space using the ultrasound, ensuring it remained at least 5 mm from any vascular structures, while an assistant held the ultrasound probe in place.

RESULTS

The study sample comprised 177 women, with a median age of 36 years (interquartile range [IQR]: 17 y). Most patients were Colombian (71.1%), followed by American (22%), Venezuelan (3.4%), and Canadian (3.4%) (Table 1).

Table 1.

Demographic Characteristics

Variable	Measure of Central Tendency or %	Dispersion Measurement
Age, y	Median: 36	IQR: 17
Sex	%, total: 177	NA
Female	100, 177
Male	0, 0
Weight, kg	Mean: 63.2	SD: 6.2
Height, m	Mean: 1.64	SD: 0.09
BMI, kg/m2	Mean: 23.49	SD: 2.32
Home country	%, total: 177	NA
Colombia	70.7, 123
United States	22.4, 39
Venezuela	3.4, 6
Canada	3.4, 6

The majority of patients had no medical history (93.2%), whereas 3 patients had a history of obesity (1.6%), 3 had hypertension (1.6%), 3 had anxiety disorder (1.6%), and another 3 had both hypertension and anxiety disorder (3%). Regarding surgical history, 166 patients had no previous intervention (95.1%), whereas 4.8% (9 patients) had undergone prior liposuction (Table 2).

Table 2.

Medical History

Variable	Measure of Central Tendency or %	Dispersion Measurement
Medical history	Total: 177, %	NA
Yes	12, 06.7
No	165, 93.2
Plastic surgical history	Total: 177, %	NA
Yes	169, 95.1
No	08, 04.8

The median duration of the procedure was 240 minutes (IQR: 40 min), with a median infiltrated volume of 1600 mL (IQR: 200 mL) for both buttocks. The median liposuction volume was 4000 mL (IQR: 700 mL), and the median fat injection volume per buttock was 800 mL (IQR: 100 mL).

Pregrafting measurements revealed slight asymmetry between the buttocks: the right buttock had a median height of 24 cm (IQR: 4 cm) from the iliac crest to the subgluteal fold, with a median width of 14 cm (IQR: 3 cm) from the posterior axillary line to the intergluteal line. The left buttock had a median height of 23 cm (IQR: 5 cm), and a median width of 18 cm (IQR: 3.5 cm).

The visualization of perforating arteries in each buttock had a median of 9 arteries (IQR: 2) per buttock. The distribution by quadrant was as follows: the left buttock’s upper outer quadrant had a median of 3 arteries (IQR: 1), the upper inner quadrant had a median of 2 arteries (IQR: 1), the lower outer quadrant had a median of 2 arteries (IQR: 1), and the lower inner quadrant had a median of 2 arteries (IQR: 1). In the right buttock, the upper outer quadrant had a median of 3 arteries (IQR: 1), the upper inner quadrant had a median of 3 arteries (IQR: 2), the lower outer quadrant had a median of 1 artery (IQR: 1), and the lower inner quadrant had a median of 2 arteries (IQR: 1). For better understanding of this distribution, see Figure 1, which shows an anatomical reference map showing the locations of the perforating arteries present in more than 80% of study participants (Table 3).

Fig. 1.

Most frequent locations for visualization of perforating arteries in each buttock.

Table 3.

Superficial Gluteal Arteries

Variable	Measure of Central Tendency or %	Dispersion Measurement
Superficial gluteal arteries	Median: 9	IQR: 2 (8–10)
Left gluteal region
Upper outer quadrant	Median: 3	IQR: 1 (2–3)
Upper inner quadrant	Median: 2	IQR: 1 (1–2)
Lower outer quadrant	Median: 2	IQR: 1 (1–2)
Lower inner quadrant	Median: 2	IQR: 1 (1–2)
Right gluteal region
Left gluteal region	Median: 3	IQR: 1 (2–3)
Upper outer quadrant	Median: 3	IQR: 2 (2–4)
Upper inner quadrant	Median: 1	IQR: 1 (1–2)
Lower outer quadrant	Median: 2	IQR: 1 (2–3)

Procedure-related complications included hematomas in 5 patients, seromas in 2 patients, and suture dehiscence in 1 patient. No cases of infection, deep vein thrombosis, pulmonary embolism, or mortality were observed (Table 4).

Table 4.

Complications

Variable	Measure of Central Tendency or %	Dispersion Measurement
Complication	Total: 177, %	NA
Yes	08, 4.51
No	169, 95.4
Complication	Total: 177, %	NA
No	169, 95.4
Bruises	05, 2.8
Seroma	02, 1.1
Sutures dehisce	01, 0.5

DISCUSSION

This study outlined the use of Doppler ultrasound-guided subcutaneous gluteal fat grafting, demonstrating that real-time visualization during the procedure significantly reduces complications and ensures patient safety. Fat embolism is a rare but serious complication of gluteal fat grafting, with an estimated occurrence of 0.06% and a mortality rate of 1 in 6214 patients.⁵ The pathophysiology of fat embolism—whether micro (MIFE) or macro (MAFE)—is linked to vascular trauma or fat dissemination under negative pressure.⁶ However, understanding these mechanisms allows surgeons to adopt preventive measures.

Evidence suggests that the subcutaneous region is the safest area for fat injection, as it is the natural site for fat deposition, has fewer major blood vessels, and is not directly affected by the gluteus maximus muscle.^1,12,13 The small blood vessels in the subcutaneous layer (diameter smaller than 2 mm) collapse under pressure, reducing the risk of fat embolism. As our findings show, the distribution of these vessels is not uniform across quadrants, highlighting the importance of ultrasound guidance to avoid vascular injury.¹⁴ This supports the Florida statement that mandates the use of ultrasound-guided fat injections. In contrast, intramuscular fat grafting carries a higher risk of thrombotic events,⁴ as the gluteal veins’ variable distribution in the intramuscular plane does not allow us to have a safe zone for fat injection without real-time visualization.¹⁵

Our study demonstrated that Doppler-guided fat grafting, with a 5-mm safety margin, resulted in zero thrombotic events—consistent with previous studies using ultrasound-guided subcutaneous fat grafting.^9–11 The quadrant marking method we used provides surgeons with a reliable visual reference for vessel locations, facilitating safer fat grafting (the visual approach helps the surgeon to develop a detailed plan for fat grafting). Additionally, the surgeon must inject the fat using ultrasound assistance to be certain of where the fat is being deposited.

The overall complication rate of 4.51% in our study is lower than the 9%–30% range reported in the literature.³ The observed complications—hematomas, seromas, and 1 case of suture dehiscence—are typical for this procedure. The low complication rate may be due to several factors: real-time ultrasound visualization to maintain a 5-mm margin from vascular structures, the use of a 4-mm cannula to reduce the risk of vascular injury, and the use of a single upper-pole entry point, avoiding multiple ports in the lower gluteal area.⁵ Additionally, antibiotic prophylaxis was administered, and ultrasound-guided technique training ensured optimal safety.^7–17

Our study has certain limitations. As a retrospective study based on patient records, it was not feasible to explore new variables of interest, obtain missing information, or conduct interviews or follow-up with the patients.

In conclusion, subcutaneous gluteal fat grafting using Doppler ultrasound guidance meets modern safety standards by ensuring visualization of tissue during fat injection. This approach seems to reduce the risk of thrombotic events by identifying critical structures such as vascular tissues and the intramuscular plane. Prospective studies are required. We achieved aesthetic results and a low complication rate based on our experience and training in ultrasound-guided fat grafting techniques.

DISCLOSURE

The authors have no financial interest to declare in relation to the content of this article.