To our knowledge, our study is the first to report the incidence of postoperative edema in CD after enterectomy. The results have shown that the edema index increased significantly after surgery and there was approximately 71% edema, including slight edema and edema, after surgery. It was reported that about 53% (20/38) of patients develop edema after major abdominal surgery [7] and Vaughan-Shaw et al. reported that approximately 35% (19/55) of patients develop edema after emergency abdominal surgery [8]. The different incidences may be ascribed to different methods used to assess edema and the heterogeneity of patients enrolled; in the two studies, the patients had different primary diseases, physical conditions, and nutritional status.

The impact of laparoscopic surgery and open surgery on postoperative edema was compared from different aspects, as described above. A smaller number of patients with postoperative edema and lower value and increment of the edema index were found in the laparoscopic surgery group than the open surgery group. Perioperative fluid management, nutritional status, different surgery, and systemic diseases have great influences on postoperative edema [24, 25]. In the present study, we excluded those interfering factors as much as possible. All patients were in fine preoperative physical condition, including the nutritional status. Both groups adopted the same fluid infusion strategy, and each day’s volume was not different in the perioperative period. The total volume of fluid intake and output was higher in the laparoscopic surgery group than in the open surgery group. Fluid management was applied according to body weight, and if fluid infusion affected the postoperative fluid redistribution, more edema would have been found in laparoscopic surgery rather than in open surgery. Overall, we believe that it was the different surgery that influences postoperative edema, and laparoscopic surgery can reduce postoperative edema when compared with open surgery.

When compared with conventional open surgery, the benefits of laparoscopic surgery have been widely investigated and confirmed in CD [12, 13, 26–29]. The present study demonstrated those benefits as well, including reducing intraoperative blood loss and length of incision, speeding postoperative recovery, shortening hospital stay, and reducing surgical-related complications, especially incision-associated complications. Meanwhile, there were still disadvantages for laparoscopic surgery in CD [27], such as requiring experienced laparoscopic surgeons and skills, increased cost and time, and not being suited for patients with severe complications and intra-abdominal adhesions.

Unlike local edema caused by local surgery, such as thyroidectomy or hand surgery [7, 8, 30], all five segmental edema indexes increased after surgery, indicating that abdominal surgery resulted in generalized edema. The generalized edema is associated with a systemic response to surgery [4, 31, 32]. Surgical trauma and stress can lead to a multitude of systemic responses, which encompass a wide range of interlinked endocrinological, metabolic, and immunological pathways [3–6, 14, 31, 32]. Through varied pathways and mediators, the response to surgical trauma can increase the permeability of the capillary membrane and results in a redistribution of plasma proteins and fluid from the intravascular to the interstitial space [7, 33]. Less postoperative edema indicated less surgical trauma and stress of laparoscopic surgery. In the perioperative period, the levels of inflammatory and stress markers and edema index increased and decreased, with a “peak value” on POD3, indicating the natural course of stress responses and body recovery after surgery.

Postoperative edema is associated with poor clinical outcomes, such as delayed healing, more complications, slow bowel function recovery, and longer hospital stay [7, 30]. Itobi et al. reported that postoperative edema could independently predict gastrointestinal recovery, and measurement of edema can be used to identify those patients at risk of poor clinical outcomes [7]. In an animal study, when compared with open surgery, the laparoscopic surgery groups had faster intestinal transit recovery, and the faster intestinal transit recovery was associated with less edematous changes [34]. The benefits of laparoscopic surgery are associated with less postoperative edema, surgical trauma, and stress to surgery accordingly [4–6, 31]. Overall, the present study suggested that laparoscopic surgery can reduce postoperative edema and response to surgical trauma and stress, as well as speed postoperative recovery compared with open surgery. Reduction of postoperative edema may elucidate the association of laparoscopic surgery with better clinical outcomes.

However, there were limitations in the present study. First, we did not observe the evolution of body water consecutively. Most patients were with drainage tubes, electrocardiograph monitoring, and bellybands, which interfere with the result of BIA on POD1 and POD2. Second, it was not a random study. We tried to randomize patients to different surgery procedures in the same ward, but it failed. Instead, we adopted strict inclusion and exclusion criteria to reduce bias as much as possible, and there no difference in preoperative characteristics between the groups. Further randomized clinical trials are required.
We reported for the first time incidence of postoperative edema in CD. Compared with open surgery, laparoscopic surgery can reduce postoperative edema and speed postoperative recovery and reduce levels of inflammatory and stress responses to surgery for patients with CD. Alleviation of postoperative edema may contribute to enhanced recovery after laparoscopic surgery compared to open surgery.