Semilunar line diastasis frequently coexists with rectus diastasis and may compromise outcomes after isolated midline repair.

BACKGROUND: Semilunar line diastasis (SLD) is a lateral fascial separation that may coexist with rectus diastasis (RD). Persistent lateral bulging and core instability after isolated RD repair suggested that unrecognized SLD may limit functional and aesthetic outcomes. This study characterizes SLD in patients with RD and reports early outcomes after concurrent repair. METHODS: This single-center observational cohort included 13 consecutive adults with RD and SLD who underwent endoscopic abdominal wall reconstruction. The first four patients were operated on before SLD was recognized as a distinct clinical entity; two developed persistent lateral bulging, and two required secondary repairs. After introducing preoperative assessment of the semilunar lines, nine patients underwent simultaneous RD and bilateral SLD (BSLD) repair using a modified subcutaneous onlay laparoscopic approach (SCOLA), with midline and bilateral semilunar plication reinforced by wide midweight mesh. Outcomes included core stability, lateral contour, patient-reported aesthetic satisfaction, return to normal activity, and early complications. RESULTS: Concomitant RD + BSLD repair was associated with improved core stability, correction of lateral bulging, high patient-reported aesthetic satisfaction and rapid return to normal activity. No major complications occurred; minor events, including seroma and superficial wound necrosis, resolved conservatively. Patients whose BSLD was not initially repaired had persistent lateral bulging or required secondary repair. CONCLUSION: In this preliminary descriptive series, SLD appeared to be clinically relevant in patients with RD. Concomitant repair of BSLD, when present, was associated with favorable functional and aesthetic outcomes. These findings support preoperative assessment of the semilunar lines and greater awareness of SLD during RD repair.