External Ultrasound Assisted Liposuction of the Abdomen: A Report of Our Experience

Introduction
Zocchi introduced the use of ultrasonic energy to the turnescent liposuction technique in the United States 1992(1). This first combination of ultrasound and liposuction incorporated ultrasonic energy into the tip of the liposuction cannula to emulsify the fat and facilitate its removal. This became known as Ultrasound-Assisted Liposuction (UAL). This technique is currently an accepted and commonly used method, though the incidence of complications is noteworthy. The drawbacks of UAL include the added cost and operating time as well as the risk of thermal tissue injury, seromas and paresthesias (I). In 1997, Silberg introduced the concept of external ultrasound assisted liposuction (XUAL) to facilitate the standard technique with an expected decreased incidence of complications when compared to UAL. The thought was that the ultrasonic energy applied pre-operatively would loosen the intercellular connections and facilitate the removal of the fat with the traditional turnescent technique. He also predicted that other potential benefits would include reduced operating time, improved skin contracture and shorter recovery time (2). Both Silberg and Wilkinson found that XUAL was safe and beneficial in preliminary studies, noting good skin contracture, ease of fat removal and decreased post operative pain and swelling (2,3). Several other preliminary studies have shown similar benefits and no significant adverse events associated with the use of pre-operative XUAL (4, 5, 6).

This study was undertaken to report our experience with XUAL of the abdomen at a single cosmetic surgery center over a one year period. The primary question being addressed was whether XUAL of the abdomen would result in a higher rate of adverse events when compared to the traditional turnescent technique.

Materials and Methods
Beginning January 1st, 2006 fifteen consecutive patients undergoing abdominal liposuction without the use of external ultrasound were prospectively included in the study. Data collected included each patient body mass index (BMI), volume of turnescent fluid infused, fat volume removed and total volume of aspirate. The traditional turnescent technique with a 10 gauge Capistrano aspiration cannula was applied in this group of patients. These patients were labeled group 1. In addition, 6 months later, on July 1, 2006, fifteen consecutive patients were treated with external ultrasound prior to abdominal liposuction, again using the traditional turnescent technique. Each case was performed in an identical manner. The ultrasonic energy was applied to the entire abdominal area in a standard fashion using a setting of 1.5 watts/cm2 for 10 minutes immediately following infusion of the turnescent solution, with the amount infused calculated based on the turnescent technique. All patients were under general endotracheal anesthesia during the infusion, the ultrasound application and the liposuction procedure, again using a 10gauge Capistrano cannula for aspiration. Data collected included each patient’s body mass index (BMI), turnescent fluid infused, fat volume removed and total volume of aspirate. There were no pre-operative, intraoperative or immediate post-operative adverse events in any patient in ether group.

Results
The abdominal liposuction procedures were eventful in all patients in group 1 and 2. All patients were dressed with the routine post-operative abdominal compression garments with absorbent cotton padding between the skin and the garment. These were worn continually for the first 7 days in all patients and only removed for showering on post-operative day two. Post-operative instructions were given to each patient in written form with detailed information about activity restrictions, diet, wound care and follow-up appointments.

The incidence of adverse events in both groups was evaluated in the post-operative period. Adverse events were defined as excessive ederna, ecchymosis, seroma greater than 50cc, hematoma, and infection or wound breakdown. There were no cases of adverse events in any patient in the immediate post-operative period. However, at the first post-operative appointment it was notable that 2 of 15 patients in group 1 (13%) had developed a significant (>50cc) lower abdominal seroma. Both patients were successfully treated with a single closed drainage procedure in the office via needle aspiration. In group 2 at the first post-operative visit it was notable that 5 of the 15 patients (33%) presented with a significant (>50cc) lower abdominal seroma. All patients in group 2 were successfully treated with drainage of the fluid via either needle aspiration or by opening the midline lower port and placing a passive drain in several cases. An average of 2.5 drainage procedures was required for resolution of the seromas in group 2. No patient in either group required additional surgery or anesthesia, and there were no associated infections or other complications. Compression garments with padding were worn continually until the seromas had completely resolved. All patients in both groups went on to full recovery with satisfactory results. Data from both groups are presented in table 1.

Statistical analysis of our data was done with a non-pooled inference test, with alpha set at 0.05. The analysis showed that the data provided sufficient evidence that group 2 has a significantly different seroma rate with 95% confidence, which gives borderline results at 5% significance. The analysis of the data suggests that any bias would likely be removed with 25 patients per group.

Discussion
The practice of incorporating ultrasound technology with liposuction is a time-tested and well-accepted technique. For over 15 years cosmetic surgeons have used both internal and external ultrasound energy to assist in the procedure of fat removal through liposuction. The concept of external ultrasound combined with liposuction was developed by several surgeons after the incidence of complications with the internal technique were noted to be higher than the standard liposuction procedure (2, 3). The intention was to facilitate fat removal with a lower risk of adverse events. Previous studies of XUAL have shown a good safety profile and subjective clinical benefits, including less post-operative pain, swelling and bruising (1, 3). In 1997, Havoonjian also reported a higher degree of skin contracture in his preliminary study of XUAL. Based on this early data, XUAL appeared to be safe and beneficial when added to the traditional turnescent liposuction technique by Klein and Lillis in 1985.

Our study of XUAL was based on these early findings and the anticipated benefits to our patients. Silberg and Wilkinson found that some of these benefits included reduced pain, reduced ederna that resolved more quickly and a shorter recovery time. Though our results in the early post-operative period were subjectively improved, or at least not changed, the incidence of seroma formation in the XUAL group (group 2) shifted our focus from the benefits to the possible adverse events. The data were analyzed and the two groups compared, specifically noting fat volume removed, total aspirate removed and the patients` pre-operative BMI. The incidence of seroma formation was clearly linked to higher BMI and total fat volume removed. The consistent variables included turnescent volume infused, amount of ultrasound energy delivered and cannula size used during the aspiration procedure. In most patients the flanks and low back were also sculpted with the liposuction technique, however, the abdomen was the only area treated with ultrasound pre-op. It is notable that the only area to develop a seroma was the abdomen, which suggests that the ultrasound could be related to the seroma formation. The cause of the seroma formation remains unknown; however the possibilities of septal breakdown, lymphatic and venous damage and cavity formation are reasonable.

In our practice, abdominoplasty is sometimes staged following abdominal liposuction. Frequently small pseudobursas are found in the areas of prior liposuction. While this makes sense and can explain the seroma incidence in general, we do not have data to implicate XUAL in these instances, and this could be a topic of further study. It is also notable that we often external ultrasound in our liposuction patients to reduce swelling in the early post-operative period. This application has subjectively shown to be very beneficial, and seems to even reduce the duration of post operative discomfort.

Our data suggests that XUAL of the abdomen will result in a higher incidence of seroma formation when compared to abdominal liposuction without the use of ultrasound assistance. Our study is limited by the small number of patients’ involved and non-randomized design. A prospective, randomized trail with an increased number of patients would certainly add value to our literature and confirm or refute our findings of an increased incidence of seroma with XUAL of the abdomen. There could also be other variables not evaluated by our study that could have contributed to our findings. A larger prospective trail could also show that XUAL does not significantly increase the incidence of seroma formation.

Conclusions
Based on this information we have concluded that there may be increased incidence of seroma formation with XUAL of the abdomen. We have not used the technique in our abdominal liposuction cases since discovering this information and will not resume the technique until further studies prove that the benefits outweigh the risk of adverse events.

Acknowledgements
The author would like to thank Tim Hawkins, BS, MS and Randall Griffus, PhD of Dalton State College for their assistance in statistical analysis of our data.

References

1. Havoonjian, H. External Ultrasonic Turnescent Liposuction. Dermatologic Surgery. 1997; 23:1201-1206.
2. Silberg, BN. The Use of External Ultrasound Assist with Liposuction. Aesthetic Surgery Journal. July/August 1998, pp284-285.
3. Wilkinson, TS. External Ultrasound-Assisted Lipoplasty. Aesthetic Surgery Journal. March/April 1999, pp124-129.
4. Lawrence, N. The Efficacy of External Ultrasound-Assisted Liposuction: A Randomized Controlled Trail. Dermatologic Surgery. 2000;26:329-332.
5. Mendes, FH. External Ultrasound-Assisted Lipoplasty from our own Experience. Aesthetic Plastic Surgery. 2000;24:270-274.
6. Gasperoni, C. External Ultrasound Used in Conjunction with Superficial Subdermal Liposuction: A Safe and Effective Technique. Aesthetic Plastic Surgery. 2000;24:253-258.

Table 1. Patient Data