Decreasing Seroma Incidence Following Abdominoplasty: A Systematic Review and Meta-Analysis of High-Quality Evidence

Abstract Background Seroma formation is the most common complication of abdominoplasties. Many preventive interventions have been proposed, but none have been recognized as a definitive solution, partly due to varying levels of evidence (LOE) in the literature. Objectives We aimed to analyze seroma prevention methods supported by high-level evidence. Methods The PubMed database was queried through August 2023. Primary articles of interest included randomized controlled trials (RCTs), prospective comparative studies, and meta-analyses of these studies. The LOE for each article was determined according to the American Society of Plastic Surgeons Rating Scale. The “seroma occurrence ratio,” or ratio of seroma events in the interventional group to respective control group, was calculated to compare incidence rates between techniques. Results Twenty articles and 9 categories of techniques were analyzed. Study designs included 10 RCTs, 2 prospective cohort studies, 7 prospective comparative studies, and 1 retrospective randomized study. The use of progressive-tension and quilting sutures had the most data supporting a statistically significant reduction in seroma (occurrence ratio 0.306, P < .001). Tissue adhesives and preservation of Scarpa's fascia were also well reinforced (0.375, P < .01 and 0.229, P < .011, respectively), while increasing the number of drains was not (P = .7576). Meta-analysis demonstrated that compared with 2 drains alone, alternative techniques were more effective at reducing seroma occurrence (pooled risk ratio 0.33, 95% CI, 0.11-0.99). Conclusions This review highlights multiple seroma prevention techniques for abdominoplasty investigated in recent high-quality literature. We suggest future randomized comparative studies of the various seroma prevention methods to fully ascertain their efficacy following abdominoplasty. Level of Evidence: 1

Abdominoplasty is one of the most commonly performed operations by plastic surgeons. 1Among complications, such as bleeding, tissue necrosis, or infection, 2 one particular consequence of the wide area of dissection involved is an increased risk of fluid accumulation.][5][6][7] Although the acceptable standard for seroma formation is 10%, 8 incidence rates of up to 25% have been reported. 2everal mechanisms have been implicated, including disruption of lymphatic and vascular ducts, 2 dead space formation, 5 and shearing forces, causing release of inflammatory mediators. 9Although often self-limited, untreated seromas can cause wound dehiscence, infection, flap necrosis, and pseudocyst formation, resulting in poor cosmetic results and prolonged hospitalization. 7,10Given that abdominoplasties are generally elective operations, it is imperative to minimize the likelihood of seroma formation. 11any interventions have been proposed to prevent seroma formation following abdominoplasties, including suction drains, 12 fibrin sealants, 13 quilting sutures (QSs), 3 progressive tension sutures (PTSs), 14 and preservation of Scarpa's fascia. 15Of these interventions, the most commonly applied are postoperative drains implemented by 98% of plastic surgeons after abdominoplasties. 16Despite numerous studies examining these interventions, none have been recognized as the optimal method for seroma prevention. 10,17Due to sparse literature comparing the performance of these interventions with one another, there remains a broad spectrum of practices to reduce seroma formation.
Although a systematic review of prospective randomized controlled trials (RCTs) was published by Seretis et al, 18 the study's strict selection criteria excluded papers and other study designs that still demonstrated a high level of evidence (LOE) and could therefore contribute additional high-quality data.Given the body of literature added since then as well as the varying LOEs, there is a continued need for an updated and more comprehensive review of highquality publications for minimizing the risk of seroma occurrence following abdominoplasty.Therefore, the objective of this study is to analyze all currently available high-LOE publications on seroma prevention methods and compare their efficacies.

METHODS
This study adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.The PubMed database was queried for all full-text, English publications using the following search terms: ("Abdominoplasty"[Mesh] OR abdominoplasty) AND ("Surgical Wound Infection"[Mesh] OR "surgical wound infection" OR "surgical site infection" OR "Seroma"[Mesh] OR seroma).The term "infection" was incorporated as a search term to ensure that the search would return any potential studies that may have included infections secondary to seroma formation.A total of 355 results were returned on June 16, 2021 with no date restrictions.A total of 89 additional studies were returned after an updated literature search on August 23, 2023 with date restrictions from June 16, 2021 to August 23, 2023.Titles and abstracts were reviewed for relevance to interventions intended to reduce seroma occurrence following abdominoplasty.Primary articles of interest included high-quality study designs, such as RCTs, prospective comparative studies, and meta-analyses of these studies.Selected meta-analyses were reviewed for additional citations that were not retrieved upon initial query; these individual studies were included for analysis instead of the meta-analyses themselves to prevent redundancy.Retrospective studies were included only if randomized study designs were utilized.All other retrospective studies, prospective cohort studies without a comparison group, case series, and animal studies were excluded.Articles describing operations such as hernia repair, panniculectomies, abdominal wall reconstruction, and abdominal closures performed for deep inferior epigastric perforator flap harvest were also excluded.
A total of 40 articles met initial selection criteria; 2 additional articles were retrieved upon citation review of meta-analyses, and 22 articles were excluded upon full-text review.Ultimately, 20 articles were analyzed (Figure 1).The LOE for each article was determined according to the American Society of Plastic Surgeons (ASPS) Levels of Evidence Rating Scale for Prognostic/Risk Studies. 19The following data were extracted: study design, study period, number of patients, age, BMI, weight of resected tissue specimen (g), smoking status, proportion of females, technique(s) under investigation, seroma occurrence rate, methodology of diagnosing seroma, and follow-up duration.To compare seroma occurrence rates between techniques, we defined the "seroma occurrence ratio" as the percentage of seroma events in the interventional group divided by that in the control group, the definition of which varied due to inherent heterogeneity.
Microsoft Excel (Microsoft, Redmond, WA) was used to perform χ 2 tests, Fisher's exact tests, and comparison of means using nonparametric, 2-tailed, 2-sample t-tests.Yates's χ 2 tests were used for event counts (seroma or no seroma) less than 5. Interventions demonstrating 0% seroma rates were considered to have insufficient sample sizes for statistical analysis.Statistical significance was determined by P-values <.05.Meta-analysis of studies comparing standard drains and alternative techniques was performed using Review Manager (RevMan) Version 5.4 (Cochrane, London, England). 20For the meta-analysis, the primary outcome was clinical seroma occurrence reported as risk ratios with 95% CIs; estimates were pooled using the Mantel-Haenszel random-effects method.Heterogeneity was quantitatively assessed using the I 2 statistic.

Study Characteristics
Study designs included RCTs (n = 10), prospective cohort studies (n = 2), prospective comparative studies (n = 7), and retrospective randomized studies (n = 1).The year of publication ranged from 2007 to 2023, with 1 paper published prior to 2010.The average ASPS LOE was 1.1 ± 0.3.The average number of patients was 60, ranging from 20 to 160.Patients were followed postoperatively for a period ranging from 2 weeks to 20 months.They were assessed for seroma formation either clinically (n = 7), with ultrasound (n = 3), or both (n = 6); 4 studies did not specify (Table 1, Figure 2).

Seroma Rate
The use of PTS and QS showed the greatest amount of data supporting a statistically significant reduction in seroma, with 4 of 5 studies clearly demonstrating a beneficial effect compared with their respective control groups (P < .001; Figure 2, Table 2).The seroma occurrence ratio was 0.306 (P < .001;Table 4), further confirming their efficacy.
Studies examining tissue adhesives (fibrin sealants, fibrin glue, PRP, and TissuGlu) were the most numerous (n = 7) but revealed mixed results with regards to seroma reduction (3 studies demonstrated a significant benefit, but 4 studies did not; Figure 2).However, seroma occurrence ratio of tissue adhesives compared with their respective control groups was 0.375 (P < .01;Table 4), revealing a significantly lower seroma incidence.Similarly, among the 3 studies examining preservation of Scarpa's fascia, 2 demonstrated a benefit and 1 showed equivocal results (Figure 2).The seroma occurrence ratio for this technique was 0.229 (P < .001,Table 4), indicating a statistically significant reduction.
Other interventions such as continuous negative pressure drains, plasma coagulators (as opposed to monopolar electrocautery), lipoabdominoplasty (instead of conventional abdominoplasty), or triamcinolone injections all demonstrated a qualitative reduction of seroma rates (Figure 2), but statistical analysis did not support recommending these techniques (Table 4).Performing lipoabdominoplasty yielded a seroma rate of 0% compared with the control group rate of 23.8% with an insufficient sample size for statistical testing.Similarly, the use of plasma coagulators had a seroma occurrence ratio of 0.0 (control group rate: 9.1%), and statistical testing could not be performed.Continuous negative pressure drains showed equivocal results in seroma occurrence (seroma occurrence ratio of 0.164, P = .1069);however, these interventions had limited data supporting their benefit, given that only 1 study per intervention had met selection criteria.The publication on triamcinolone injections-a newer intervention for seroma reduction in abdominoplasty-reported average seroma volumes rather than proportions, and thus no occurrence ratio was calculated.Two interventions-using electrocautery instead of scalpels and using more drains (3 vs 2)-did not show a qualitative benefit in reducing seroma formation (Figure 2).The seroma occurrence ratio for electrocautery use was 1.67 (P = .1467),indicating no significant difference in seroma formation rates.The study examining 3 drains (n = 73) revealed no significant difference in seroma rates (seroma occurrence ratio of 0.658, P = .7576).

Meta-Analysis
The total number of patients was 113 for alternative techniques and 111 for standard drains, because 1 study 24 contained 2 separate cohorts eligible for analysis, and the control group from this study was counted twice (Figure 3).As mentioned above, the total number of unique patients was 203 (Table 3).Three studies comparing PTS and QS to drains in abdominoplasties were meta-analyzed to reveal a risk ratio of 0.29 (95% CI, 0.05-1.66,I 2 = 74%; Figure 3).Analysis of lipoabdominoplasty vs conventional drain use revealed a risk ratio of 0.10 (95% CI, 0.01-1.62)lacking statistical significance; however, only 1 study (n = 1) was included.Finally, analysis of 3 suction drains revealed a risk ratio of 0.66 (95% CI, 0.19-2.26),demonstrating no significant reduction in seroma formation.Although none of the individual 3 interventions examined in the meta-analysis demonstrated efficacy in reducing seroma formation, the overall pooled analysis demonstrated a statistically significant risk ratio of 0.33 (95% CI, 0.11-0.99,I 2 = 57%) compared with the standard approach of placing 2 closed-suction drains.

DISCUSSION
Seromas are one of the most common complications following abdominoplasty.The current review highlights recently published seroma reduction interventions with high-quality study designs.All of the selected articles were published within the past 2 decades, underscoring the recency of these techniques and indicating that many are still under investigation (Table 1).By exclusively evaluating papers with a high LOE (average grade 1.1 ± 0.3; Table 1)-with a majority of the selected publications comprised of RCTs and prospective comparative studies-we provide an expanded and contemporary overview of strong evidence-based recommendations, regarding the use of various methods to minimize seroma formation following abdominoplasty.Interestingly, in agreement with Seretis et al, 18 we found that compared with conventional abdominoplasty, seroma rates can be reliably reduced by certain surgical techniques, which will be discussed in further detail in the following paragraphs.
Overall, 9 categories of techniques were analyzed (Table 1, Figure 2).The majority of available data pertains to tissue adhesives followed by PTS, QS, preservation of Scarpa's fascia, electrocautery compared with scalpels for dissection, and plasma coagulators compared with conventional monopolar electrocautery.The remaining techniques-triamcinolone injections, 11 lipoabdominoplasty, 24 continuous negative pressure drains, 27 and using 3 rather than 2 closed-suction drains 32 -have only 1 high-quality publication each.While there is limited data for these techniques, the existence of high-level evidence suggests that they are already under close investigation.Furthermore, these techniques, with the exception of using 3 drains, qualitatively demonstrated potential benefit in reducing seroma formation.Given their promising results but acknowledged limitations due to small study numbers, further investigations are warranted to arrive at more definitive conclusions for these techniques.
Qualitative analysis of each technique revealed additional insight (Table 2).The technique with the least ambiguity in efficacy is the use of PTS or QS, which has demonstrated consistently positive outcomes in abdominoplasty (Table 2). 10,21,22,24Among the 5 PTS/QS studies, all but 1 study 35 demonstrated a clear advantage of utilizing PTS or QS over other techniques to mitigate seroma formation.Furthermore, although 1 study showed no difference in PTS compared with a lysine-derived urethane surgical adhesive (TissuGlu), it should still be noted that both groups achieved a 0% seroma rate in a small cohort of 10 patients each, and PTS was still considered efficacious. 35The other 2 categories that demonstrated a statistically significant difference in seroma formation rates were the use of tissue adhesives and preservation of Scarpa's fascia.While these techniques are well-reinforced, 22,[29][30][31][32]35 there is conflicting evidence regarding their definitive benefit, 17,21,25,26,33, and there may not yet be enough data to draw a conclusion at the time of this review. Aditionally, among the studies that demonstrated a substantial benefit, only 1 study 23 reported a formal power analysis, bringing into question the statistical reliability of the conclusions presented in these publications despite their high ASPS-rated LOE.
Two techniques that have not demonstrated a significant benefit in seroma reduction and had equivocal statistical differences were the use of electrocautery (vs scalpel) for dissection 30,36 and using 3 drains instead of 2 drains 32 (Table 2).Given these findings, it is likely that other factors and methods are more important in influencing seroma occurrence rate following abdominoplasty.Notably, Pisco et al 32 examined the use of 3 drains in the context of Scarpa's fascia preservation, which alone has already been demonstrated to reduce seroma formation and may have confounded the study's conclusions. 37Looking more closely at the method of dissection, while electrocautery may provide enhanced intraoperative control of bleeding, using a scalpel is thought to preserve overall tissue health by minimizing the amount of thermal injury and resultant inflammation and fluid accumulation. 38,39With regards to abdominoplasty, utilizing scalpel dissection may be more beneficial for seroma reduction when compared with electrocautery, 36 but the evidence remains mixed overall and may depend on the level of each surgeon's experience. 30Regardless, when deciding between scalpel or electrocautery for surgical dissection of such a large tissue flap, factors other than seroma formation, such as hematoma risk, bleeding risk, and total operating time, must be carefully considered.
Two studies compared the rate of seroma formation following electrocautery and the use of plasma coagulators in abdominoplasty. 7,34Although plasma coagulators (ie, PEAK PlasmaBlade or PlasmaJet) yielded a promising seroma formation rate of 0%, the 2 studies reported a similarly low seroma rate in the electrocautery group, thereby questioning the specific benefit of using plasma coagulators in this context.Overall, these 2 studies had insufficient data to perform an appropriate statistical analysis, warranting future studies before arriving at an evidence-based recommendation.Similarly, although triamcinolone injections 11 and lipoabdominoplasty 24 demonstrate promising initial results in reducing seroma formation rates, consistency across multiple studies and larger sample sizes are required to achieve a more meaningful conclusion.Notably, the 1 lipoabdominoplasty paper included in this review 24 recorded a mean volume of 1327 cc of lipoaspirate after infiltration using a superwet technique.The authors did not specify the method of liposuction, but there is also currently no strong evidence, suggesting increased seroma rates using ultrasound-assisted liposuction compared with powerassisted liposuction.Although higher lipoaspirate volumes may be associated with increased seroma rates, the overall evidence is mixed, partly due to variations in abdominoplasty techniques and degree of flap undermining, the latter of which likely plays a more direct role in determining seroma risk. 40In fact, a recent paper on surgical trends highlighted lower complication rates despite increased utilization of abdominal flap liposuction among plastic surgeons; the authors also partially attribute the decreased complication rates to diminished flap undermining, 41 emphasizing the multifactorial nature of seromas and other complications.Similarly, although Dillerud 42 published a higher rate of seroma formation when liposuction was combined with abdominoplasty compared with abdominoplasty alone, Gould et al 43 showed no difference in seroma rates when liposuction was used with PTS, indicating that liposuction alone may not be as influential as once thought in increasing seroma risk.
A selective subgroup meta-analysis was performed to evaluate seroma occurrence in studies controlled by the use of standard drains (Figure 3).Most of the data in the meta-analysis was derived from studies on PTS and QS.Lipoabdominoplasty and the use of 3 drains-while included in the meta-analysis and demonstrate positive or equivocal outcomes-are limited by smaller sample sizes.Overall, our meta-analysis illustrates that compared with the standard placement of 2 drains, alternative techniques are likely more effective at reducing seroma occurrence, which is supported by another recent meta-analysis 18 and motivates further research in this area.
Among the interventions examined in this systematic review, PTS and QS demonstrated the most reliable data supporting efficacy in reducing seroma formation rate.These studies were more numerous and consistently supported their ability to reduce seroma rates when applied in conjunction with drains. 10,21,22,24,35,While subgroup meta-   analysis demonstrated that PTS and QS do not have a statistically significant effect on seroma prevention when compared with 2 standard drains, this result may be limited by the sample size of the meta-analysis.Nevertheless, the results of our analysis should be thoughtfully compared with those reported by other authors of publications with lower LOEs.Notably, this review examined PTS and QS together because they both involve suturing the raised abdominal flap to the underlying abdominal wall fascia to minimize dead space. 5,6However, the definitions of these 2 techniques may vary between authors, and the techniques themselves also likely vary between surgeons, which may influence overall outcomes.There are several limitations to this systematic review.When performing the initial search, traditional abdominoplasty was not distinguished from Fleur-de-Lis abdominoplasty, although recent literature shows that this would be unlikely to influence seroma occurrence. 11The assignment of LOEs to each publication can be subject to interpretation bias and, consequently, selection bias; furthermore, Level 1 evidence as defined by ASPS does not necessarily correspond to high-quality evidence, and there are several factors omitted from the guidelines that can influence the quality of evidence regardless of study design. 44Additionally, as this study is a systematic review, there is inherent variability among patient populations and surgical techniques which may influence the efficacy of certain seroma prevention methods (variations in PTS techniques are a primary example).There was also a lack of standardization of the method used for diagnosing seroma that limited our analysis (Figure 4); we decided to examine clinically diagnosed seroma because of implied clinical significance, and the volume threshold for ultrasound-guided diagnosis may vary between practitioners.Finally, the number of eligible studies for the meta-analysis was limited by study designs: Not all studies had the same control group, but perhaps having 1 (ie, placement of 2 closed-suction drains) would be useful to enable a more robust metaanalysis in the future.

CONCLUSIONS
This systematic review highlights multiple techniques used to reduce seroma occurrence in abdominoplasty that were investigated in recent high-quality literature.The beneficial effects of PTS and QS, tissue adhesives, and preservation of Scarpa's fascia are reinforced by high-quality evidence that is relatively consistent across multiple sources.Other potentially beneficial techniques such as triamcinolone injections, adjunctive liposuction, continuous negative pressure drains, and the use of plasma coagulators (vs conventional electrocautery) warrant further discussion and research in order to arrive at a more definitive consensus.Notably, there is a difference between qualitative recommendations and statistically significant evidence that should be considered prior to integrating new techniques into practice; furthermore, establishing standardized control groups across multiple studies would afford more meaningful pooled comparisons.Overall, we suggest future randomized comparative studies of the aforementioned seroma prevention methods under investigation to fully ascertain their efficacy following abdominoplasty.

Figure 1 .
Figure 1.Flowchart describing our systematic literature review methodology.

Figure 2 .
Figure 2. Summary of recommendations on interventions included in this review.The number of studies making each recommendation is reported.

Figure 3 .
Figure 3. Forest plot of the meta-analysis comparing seroma rates of alternative techniques to those of standard drains.

Table 1 .
Summary of Data Collected From the Selected Articles n/s, not specified; PPP, platelet-poor plasma; PRP, platelet-rich plasma; PTS, progressive tension suture; QS, quilting suture; RCT, randomized controlled trial; US, ultrasound.

Table 2 .
Summary of Techniques Other Than Standard Suction Drains Used by the Selected Studies to Prevent SeromaOccurrence Following Abdominoplasty patients undergoing each specified intervention (excluding patients in comparison/control groups) was recorded.PTS, progressive tension suture; QS, quilting suture.a Includes fibrin sealant, fibrin glue, platelet-rich plasma, and TissuGlu).

Table 3 .
Summary of Characteristics of Patients Included in the Meta-AnalysisAlternative technique Standard drains P-value

Table 4 .
Seroma Occurrence Ratios for Each Technique