Umbilical hernia repair is one of the most common surgical performance in general surgery. Up to now, the use of suture repair has been the preferred technique for small umbilical hernia defects without any gold standard procedure. Mesh have been reserved to larger umbilical hernia defects. However, there is an increasing evidence that mesh reinforcement could be advantageous to lower the high recurrence rates also in smaller umbilical hernias. A remained important question is in what anatomical position the mesh should be placed. The investigators hypothesize that the use of an onlay mesh in small umbilical hernia defects can reduces recurrence rates without increasing postoperative complications compared to a suture repair.

The trial is a prospective multicenter randomized clinical trial comparing onlay mesh to suture repair. Two hundred and eighty-eight patients with a primary elective umbilical hernia below and equal to 2 cm from seven Swedish participating surgical centers will be enrolled. Randomization will be performed intraoperatively following the measurement of the defect (with stratification for centra and for the defect size) to either closing the small umbilical defect with a simple primary suture repair or closing the defect with a simple primary suture repair with an attached small flat lightweight polypropylene only mesh on the aponeurosis. Trial participants, investigators and follow-up clinical surgeons will be blinded for the assigned allocation. The primary endpoint will be recurrence at 1 and 3 years. Secondary endpoint will be surgical site postoperative complications at 30 days and pain 1 year after surgery. As follows, participants will be visiting the outpatient clinical at 30 d, 1 year and 3 year after surgery.

All analyses will be performed according to the intention to treat principle and as specified in the analyses plan of the study protocol.

There is no randomized clinical trial today comparing recurrence rates between an onlay mesh repair and a suture repair for small umbilical hernia defects. The trial design allows a good detection of differences in recurrence with the large sample size and the adequate follow-up. Surgeons are becoming more aware of the mesh's advantage even for the small defects, but are reluctant to use a mesh due to anatomical positions with a large dissection and an increased risk of complications. A small onlay mesh could be an easy and safe method of choice for small umbilical hernia defects to avoid increased recurrence rates. Guidelines for small umbilical hernia repairs have stressed out the need for reliable data for treatment recommendations. The investigators can expect that the trial will have a direct implication on small umbilical hernia repair standards.

The clinical study protocol has underwent full external peer review as part of the funding process with Research funding from SLL (Stockholms läns landsting) Karolinska Institutet. Approval of the protocol by the Swedish Ethical Review Authority was obtained at December 2018 and January 2020.

Inclusion Criteria

• Elective surgery of a primary umbilical hernia with a defect ≤ 2 cm that is measured clinically or with radiology.

Exclusion Criteria:

• Incisional hernia: previous surgery in the area of the operation
• Recurrent umbilical hernia
• Epigastric hernia (a defect from 3 cm below the xiphoid till 3 cm above the umbilicus) [20]
• Another operative procedure at the same time (i.e. cholecystectomy)
• An umbilical hernia with a defect > 2 cm measured clinically, with radiology or intra-operatively
• Multiple defects
• Pregnancy
• Infected wounds
• Acute operation (incarcerated hernia)
• BMI>35
• Ascites
• Immunosuppression
• Anticoagulant treatment (Warfarin, NOAK)
• Connective tissue disease