Background Protein denaturation and collagen contraction occur when living tissue is heated to well-defined temperatures. The result is reduced volume and surface area of the heated tissue. Objective To evaluate the adverse events of procedures in which a helium-based plasma technology was used with and without ultrasound-assisted liposuction for the coagulation of soft tissue. Methods A multicenter retrospective chart review was performed in which patients (n=192) were divided into two groups: one that received only soft tissue coagulation and the other that received both soft-tissue coagulation and liposuction. Each of the two groups was subdivided into patients with and without adverse events, including seroma. Odds ratios for adverse events were calculated for both demographic and surgical subgroups. Seroma data were analyzed separately. Results No serious adverse events were observed. Forty-six (24.0%) patients reported 51 total adverse events. Seroma was the most frequently occurring adverse event with 13 patients (6.8%) reporting 17 (33.3%) events in 12 body areas. In these cases, all areas were treated with both liposuction and soft tissue coagulation. Seroma was not observed in patients receiving soft tissue coagulation alone. Patients aged 61 to 76 years and males were more likely to experience seroma or other adverse event than younger patients or females, respectively. Conclusions The use of the helium-based plasma technology for soft tissue coagulation in combination with ultrasound for liposuction is associated with non-serious adverse events. The most frequently occurring adverse event, seroma, was not observed in patients treated with helium-based plasma technology alone.