Body contouring surgery after massive weight loss is associated with increased complication rates. Therefore, presurgical optimization of comorbidities and a check-up for surgery-related parameters to minimize postoperative complications are of high importance. The consensus among experts is to perform postbariatric surgery rather cautiously or even refuse to perform such procedures in patients who are still markedly obese (Hauck et al. 2019; Promny et al. 2021). The target weight and stability of body weight are important conditions for the decision upon an operative procedure. Moreover, interventions should be performed by experienced surgeons (Dragu and Horch 2014). A multistage concept is recommended in cases requiring contouring of various body parts to reduce postoperative complications.

As a consequence of massive weight loss, excessive skin and soft tissue remain, posing an often underestimated burden for the patient. Body contouring surgery can help to overcome chronic inflammatory skin disorders triggered by extensive skin-to-skin contact and psychological stress (Stumpfe et al. 2022; Baillot et al. 2013).

Health-related changes following bariatric interventions in obese patients are well documented in the literature. Metabolic diseases such as diabetes or hypertonia as well as skeletal disorders are positively influenced. Moreover, the optimization or even normalization of laboratory markers is known (Mohapatra et al. 2020). On the other hand, bariatric procedures can influence the absorption or metabolization of different nutrients with influence on laboratory markers necessitating routinely performed blood controls and lifelong substitution of vitamins and micronutrients.

Although bariatric surgery is currently a common procedure with an elevated risk of wound healing problems, to date, in postbariatric patients, there is a lack of knowledge about the influence of bariatric interventions on laboratory markers following body contouring procedures. The presented data in this study reveal no exceptional variances in the course of laboratory markers independent of the bariatric procedure or the body contouring intervention. Preoperative control, especially for surgery-related markers such as hemoglobin, leukocytes, thrombocytes, or creatinine, presented normal values. As expected, postoperative changes from the baseline in different values occurred, but there was no need for a medical intervention such as blood transfusion (except for one patient) or drug administration related to the variational value (except for five patients with infections). Even though values for hemoglobin were decreased and those for CRP were increased at the time of discharge from the hospital, those values presented a correction compared to the latest values measured during the hospital stay and were normalized by 2 months postoperatively. If hemoglobin levels are reduced preoperatively, Bayter-Martin et al. recommend parenteral iron and erythropoietin administration (Enrique Bayter-Marin et al. 2021). In contrast, the administration of iron to treat preoperative iron deficiency anemia was not considered useful by Ng et al. (Ng et al. 2015). Bleeding complications are common in this highly elective patient group. Risk should be reduced to a minimum, as bleeding complications lead not only to revisional surgery but also to more than three times more hospital readmissions (Vieira et al. 2017). Additionally, the long-term risk of secondary postoperative hematoma formation can occur (Dragu et al. 2009; Stumpfe et al. 2020). In elderly patients over 60 years of age, the risk for bleeding and hematoma was found to be increased (Fliss et al. 2022).

According to Correia-Sa and colleagues, a preoperatively elevated CRP value indicated an increased risk for the formation of hypertrophic scars (Correia-Sa et al. 2017). The study examined laboratory markers before surgery and during the course of 5 days afterwards. Patients who developed hypertrophic scars in the clinical follow-up 6 months postoperatively already had an elevated CRP value before surgery. Pathologic scarring is thought to be caused by a prolonged or increased inflammatory response (Niessen et al. 2004). For this reason, current prophylactic and treatment strategies (e.g., intralesional corticosteroid injection or adjuvant radiotherapy/brachytherapy) focus mainly on limiting inflammatory processes (Lee and Jang 2018). Long-term studies evaluating scar formation are necessary to underline or disprove this association.

In addition to the standard laboratory markers, a detailed evaluation of nutrients was performed in this study. Bariatric surgical approaches can cause or worsen nutrient deficiencies. Nutrient deficiency can lead to various health problems, including weakness, hematoma, and infections (Bal et al. 2012; Gruener et al. 2022). The existing guidelines form the basis for recommendations on supplementation and treatment after weight loss surgery (Stroh et al. 2017). Standardized approaches to micronutrient supplementation and clinical and laboratory screening for micronutrient deficiencies are needed after bariatric surgery. Lifelong supervision in an obesity center for bariatric surgery is mandatory (Mohapatra et al. 2020). In this context, care should be taken to avoid excessive intake of vitamin supplements, as this can lead to acute kidney failure and, over time, to chronic kidney failure (Francesco Daher et al. 2017). Patients with regular attendance at an obesity center as well as with high compliance showed sufficient medication supplementation. Our data showed that there is no increased risk for surgery due to a deficiency of micronutrients if the abovementioned steps have been carried out regularly. If the recommended laboratory controls are regularly performed, there are no abnormalities to be expected in the specific and general laboratory markers in bariatric surgery patients.

Bariatric weight loss surgery is generally associated with a higher risk for complications compared to dietary weight loss (Staalesen et al. 2012). However, in this study and in the literature, there is no evidence for an increased complication rate between the individual bariatric procedures (Garcia Botero et al. 2017; Pajula et al. 2019). A risk factor for wound healing problems is described by a higher resection weight and a preoperative BMI higher than 30 kg/m2 (Parvizi et al. 2015). Further risk factors are known and should be taken into account in the planning of surgical interventions in this patient group. Overall, the complication rate in our patient population was low. In centers with high experience in the field of bariatric surgery and body contouring procedures, those interventions can be performed with a high level of safety.

According to the data found in this study, the authors recommend that certain laboratory parameters should be consistently monitored. A general baseline measurement should be obtained, especially for the parameters hemoglobin, thrombocytes, leukocytes and CRP, and creatinine. If the hemoglobin value is noticeable, it should be controlled in advance or optimized, if necessary (Dragu and Horch 2014). As considered above, the administration of iron and erythropoietin for preoperative optimization of hemoglobin is controversial (Enrique Bayter-Marin et al. 2021; Ng et al. 2015). Due to the correlation analysis in cases of high resection weight and high seroma production as well as in cases of an increased risk of seroma formation, the abovementioned parameters hemoglobin, thrombocytes, leukocytes, and creatinine are recommended to be controlled in the postoperative course (Salari et al. 2021). The values mentioned should likewise be within the normal range preoperatively in order to be able to intercept complications in the event of a significant discrepancy (delta).

If there is no regular visit at an obesity center, patients are recommended to check values for protein, albumin, arginine, glutamine, vitamin a, vitamin b12, vitamin c, folate, thiamin, iron, zinc, and selenium before body contouring in accordance with the literature (Agha-Mohammadi and Hurwitz 2008). The healing of wounds and optimization of the immune system are influenced by these parameters (Hurwitz et al. 2008). Marouf et al. claim that a valuation of the prealbumin or transferrin level shows the patient’s current nutritional status the best (Marouf and Mortada 2021). However, Botero et al. did not find a correlation between preoperative serum albumin levels and the incidence of complications in patients with body contouring procedures (Garcia Botero et al. 2017).

This study is limited by its retrospective design. A further subdivision into detailed subgroups — with an already small subgroup size — is not meaningful and comparable due to the resulting group size. A dietary weight loss reference group would be a preferable addition but seems infeasible due to the lack of laboratory markers in the long term before and after body contouring procedures. Future studies could focus on factors influencing certain diets, such as vegetarian, vegan, alkaline, and ketogenic forms. These can have far-reaching effects on the laboratory parameters already considered and thus also on the results of the body contouring operation.

Considering the safety of body contouring procedures after bariatric interventions in view of surgery-related and specific laboratory markers, we could not find particular risks. The correlations found between an increased amount of drain fluid and the parameters hemoglobin, thrombocytes, leukocytes, and creatinine should be assessed in further studies including a larger patient population. The aforementioned correlations were of no clinical relevance in this study. Patients with more drained fluid had higher alterations in the aforementioned parameters; however, these alterations were not related to necessary treatment. Despite these results, perioperative monitoring of laboratory markers is essential, as well as frequent control by a specialized center. Comorbidities require special attention for related laboratory markers during the entire treatment. Similar to any other relevant surgical procedure, presurgical check-ups for variations in laboratory markers are important in the planning of surgical interventions. Hence, these are further relevant data to improve the safety of body contouring interventions and reduce complications.