Abstract: Objective　To explore the strategy and technical points of harvesting outer muscle-sparing pedicled transverse rectus abdominis musculocutaneous （ms-TRAM） flaps to improve the blood safety. Methods　 From June 2020 to March 2023， 47 female patients with breast cancer were treated with different forms of ms-TRAM flaps to complete unilateral autologous breast reconstruction. Specifically， there were 31 cases of immediate breast reconstruction， 3 cases of immediate delayed breast reconstruction， and 13 cases of delayed breast reconstruction. There are three specific forms of skin flaps included： unilateral outer ms-TRAM flaps combined with traditional pedicled rectus abdominis musculocutaneous flaps （16 sides）， unilateral ms-TRAM flaps combined with free rectus abdominis musculocutaneous flaps transplantation （14 cases），and bilateral outer ms-TRAM flaps （17 cases）. Intraoperative fluorescence contrast was used to assess the inferior vascular pedicle carried by ms-TRAM flaps preserving the lateral rectus abdominis muscle when the flap was poorly vascularized. Results　 A total of 24 patients with lateral rectus abdominis muscle preserved had malvascularity， and 21 of them had additional anastomosis of subabdominal vascular pedicle carried by ms-TRAM flaps retaining lateral rectus abdominis muscle， preserving all the flaps successfully survived without obvious complications. The other 3 cases were not treated with special treatments， including 2 cases of partial necrosis， which healed after resection of the necrotic part and conservative dressing change， and 1 case was remedied with pedicle latissimus dorsi flap. After 12-36 months of follow-up， with an average of 23.9 months， the shape of the reconstructed breast was acceptable， the texture was satisfactory， and the basic symmetry was presented. Only linear scars were left in the donor area and the breast recipient area， and the abdominal wall function was not significantly affected. Conclusion　ms-TRAM with preservation of the lateral rectus abdominis muscle is limited by anatomical defects and unstable vascularization， and additional anastomosis of the subabdominal vascular pedicle pressurizes the flap to ensure safe vascularization.

Key words: Breast cancer, 　Rectus abdominis musculocutaneous flap, 　Breast reconstruction