As a minimally invasive surgery, laparoscopic surgery brings many short-term and long-term benefits over open surgery, such as reducing postoperative complications, promoting postoperative recovery, and reducing hospital stay [1, 2]. The benefits of laparoscopic surgery over open surgery are associated with reducing surgical trauma and stress, but the precise mechanism is still unclear [3, 4].

Surgical trauma and stress can lead to a multitude of systemic responses, which can be reflected by the levels of inflammatory and stress markers such as cytokines, acute phase proteins, and stress hormones [4–6]. The response increases the permeability of the capillary membranes and affects fluid redistribution between intravascular and interstitial space, which can lead to local and general edema postoperatively [7–9]. Previous studies showed that postoperative edema is associated with poor clinical outcomes [7, 8]. We hypothesized that when compared with open surgery, laparoscopic surgery can alleviate postoperative edema by reducing surgical trauma and lower level of systemic response, which may contribute to better outcomes of laparoscopic surgery.

Crohn’s disease (CD) is a chronic inflammatory gastrointestinal disorder, characterized by phases of remission and frequent relapses that often need surgical intervention [10]. Surgery is often necessary to treat complications such as stricture, fistula, abscess, bleeding, or failed responses to medical therapy [10, 11]. Laparoscopic surgery has been widely applied in patients with CD because its safety and feasibility were confirmed, and many studies have exhibited its advantages over open surgery [12–14]. However, there are no reports about postoperative edema in patients with CD.

Bioelectrical impedance analysis (BIA) is widely used to measure body water to assess body water, find nonclinically evident edema, and manage fluid [15–18]. Compared with subjective methods, BIA is a more objective, numerical, and credible method to assess body water and edema, particularly for nonclinically evident edema [15]. The edema index, defined as the ratio of extracellular water to total body water, can present the level of whole body edema and segmental edema. According to the edema index, edema can be graded to slight edema (defined as edema index ≥ 0.395) and edema (defined as edema index ≥ 0.400) [19]. Segmental edema includes five segments as follows: right arm, left arm, trunk, right leg, and left leg [20].
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.

The aim of this study is to investigate the postoperative edema in CD and compare the impact of laparoscopic and open surgery on postoperative edema in a single disease.