Surgical site infections are among the most frequent complications after abdominal surgery and are associated with impaired wound healing, prolonged hospital stay, additional treatments, and increased healthcare costs. Closure of the subcutaneous tissue before skin closure is commonly performed in abdominal surgery, but the available evidence supporting this practice remains limited and heterogeneous, particularly outside caesarean section surgery.

The SUTURE trial is a prospective, randomized, patient- and assessor-blinded superiority trial evaluating whether subcutaneous tissue closure reduces the incidence of surgical site infections after abdominal surgery. Adult patients undergoing elective open or laparoscopically/robotically assisted abdominal surgery with an abdominal incision of at least 6 cm will be randomized intraoperatively after fascial closure to either subcutaneous tissue closure using interrupted Vicryl® 2-0 sutures or no subcutaneous tissue closure. The primary endpoint is the occurrence of surgical site infection according to CDC criteria grade I-II within 30 days after surgery.

The trial aims to provide high-quality evidence on whether routine subcutaneous tissue closure should be recommended as a standardized wound closure strategy in abdominal surgery.

Surgical site infections (SSI) remain a common and clinically relevant complication after abdominal surgery. They may lead to delayed wound healing, postoperative pain, prolonged hospital stay, additional outpatient or inpatient wound care, antibiotic therapy, reoperations, reduced patient satisfaction, and increased healthcare costs. Despite improvements in perioperative care, SSI prevention remains an important target in abdominal surgery.

One potentially modifiable factor is the technique of abdominal wall closure, particularly whether the subcutaneous tissue is closed before skin closure. Subcutaneous suturing is frequently used in clinical practice, especially in patients with thicker subcutaneous tissue layers. However, the available evidence regarding routine subcutaneous tissue closure in non-caesarean abdominal surgery remains limited and heterogeneous. Therefore, high-quality randomized data are needed to clarify whether subcutaneous tissue closure reduces postoperative SSI after abdominal surgery.

The SUTURE trial is a prospective, randomized, patient- and assessor-blinded, single-center superiority trial conducted at the University Hospital Augsburg. Adult patients scheduled for elective abdominal surgery with an abdominal incision of at least 6 cm are eligible for screening. This includes open abdominal surgery as well as laparoscopically or robotically assisted procedures requiring specimen extraction through an abdominal incision of at least 6 cm.

Randomization is performed intraoperatively after fascial closure and before skin closure. Patients are allocated in a 1:1 ratio to either subcutaneous tissue closure or no subcutaneous tissue closure. In the intervention group, the subcutaneous tissue is closed using interrupted Vicryl® 2-0 sutures. In the control group, no subcutaneous sutures are placed before skin closure. Skin closure is performed according to the standardized institutional approach, using skin staples for open laparotomy and continuous intracutaneous Monocryl® 3-0 sutures for laparoscopically or robotically assisted procedures.

Patients and postoperative outcome assessors are blinded to treatment allocation. The operating surgeon cannot be blinded due to the nature of the intervention. Postoperative wound assessments are performed during the inpatient stay and at the predefined 30-day follow-up visit. The primary endpoint is the occurrence of SSI according to CDC criteria grade I-II within 30 days after surgery.

Secondary endpoints include wound closure time, postoperative antibiotic therapy for SSI, wound healing disorders and their extent, wound dehiscence, reoperation related to wound complications, all SSI including CDC grade III, complete wound healing at follow-up, length of hospital stay, patient-reported scar assessment and quality of life, as well as wound-care-related healthcare resource utilization.

The aim of the trial is to determine whether routine subcutaneous tissue closure reduces the incidence of clinically relevant SSI after abdominal surgery and whether this technique should be recommended as a standardized component of abdominal wound closure.

Inclusion Criteria:

• Adult patients (≥18 years)
• elective laparotomy (midline laparotomy, transverse laparotomy, subcostal incision, thoracoabdominal incision, or extended Pfannenstiel incision) or laparoscopically assisted abdominal surgery with a specimen extraction incision of at least 6 cm.

Exclusion Criteria:

• Emergency laparotomy.
• Anticipated or documented non-compliance with study procedures or follow-up.
• Patients in whom primary wound closure cannot be achieved at the end of surgery.
• Patients unable to provide informed consent.

Individual participant data will not be made publicly available due to ethical, legal, and data protection restrictions. De-identified data may be made available from the principal investigator upon reasonable request and subject to institutional approval, if permitted by applicable regulations and participant consent.