The goal of this observational study is to contribute to a better understanding of the perioperative kinetics of intestinal microbial composition and association with surgical site infections.

The main question this study aims to determine if:

• Patients undergoing surgery develop transient intestinal dysbiosis
• Such transient dysbiosis is associated with translocation to the systemic circulation and surgical site infection

Patients undergoing elective abdominal surgery will be included prospectively. Informed consent will be obtained. From patients the following information and samples will be collected:

• Perioperative: Baseline health data, nutrition data, measurement body composition, glucose monitoring

• Intraoperatively:

  • Mucosal swabs
  • Blood from central venous catheter and portal vein
  • Mesenteric lymph node
  • Intestinal specimen
  • Bile
  • Subcutaneous biopsy

• Postoperatively:

  • If a surgical site infection occurs samples from infected site

Inclusion criteria:

• Patients undergoing laparoscopic colorectal resection with anastomosis or patients undergoing duodeno-pancreatectomy.
• Elective surgery
• Informed consent
• Age > 18 years

Exclusion criteria:

• Emergency surgery
• Other surgery 30 days prior to surgery
• BMI <18 or >50kg/m2
• Planed simultaneous second procedure with involvement of the intestinal tract
• Cholestasis with cholangitis, hepatic disease (defined as cirrhosis Child B or C) or renal disease (acute or chronic renal failure defined as eGFR≤ 30ml/min)
• Severe active enteritis or colitis, malabsorption, enteric infections
• Pancreatitis

Patients undergoing elective abdominal surgery