IntroductionTo investigate the effect of subcutaneous fat suture closure versus non-closure at cesarean section (CS) on long-term cosmetic outcome.Material and MethodsWomen undergoing planned or unplanned CS were randomized to either subcutaneous fat suture closure or non-closure using a 1∶1 allocation algorithm. Participants and outcome assessors were blinded to group allocation. Scar evaluation was performed after two and six months. Primary outcome measures were Patient and Observer Scar Assessment Scale (POSAS) summary scores six months after surgery. Secondary outcome measures were Vancouver Scar Scale (VSS) summary scores, retraction of the scar below the level of the surrounding skin, duration of surgery, and development of hematoma, seroma, surgical site infection (SSI) or wound disruption. Data were analyzed according to the intention to treat principle.ResultsA total of 116 women were randomized and 91 participants, 47 in the closure and 44 in the non-closure group, completed the trial and were analyzed. There were no differences in patient morphometrics or surgery indications between groups. At two and six months no significant differences were found with respect to POSAS or VSS scores between groups. After two months significantly more women in the non-closure group described their scar as being retracted below the level of the skin (36% vs. 15%, p = 0.02) whereas no difference was observed at six months. There were significantly more hematomas in the non-closure (25%) compared to the closure group (4%) (p = 0.005). There was no difference in duration of surgery, SSI, seroma formation or wound disruption between groups.ConclusionsSuture closure of the subcutaneous fat at CS does not affect long-term cosmetic outcome. (Level I evidence).Trial RegistrationClinicalTrials.gov NCT01542346.