DIEP-MDS for Risk Stratification of Flap Vascular Compromise and Failure in Breast Reconstruction

Deep inferior epigastric artery perforator (DIEP) flap breast reconstruction is a cornerstone technique in autologous breast reconstruction after mastectomy. By preserving the rectus abdominis muscle while providing durable soft-tissue replacement, the DIEP flap provides reliable reconstructive volume and favorable aesthetic outcomes. Despite these advantages, the success of DIEP flap breast reconstruction depends critically on achieving and maintaining adequate flap perfusion. Early postoperative flap-related vascular compromise-including venous congestion, arterial insufficiency, pedicle thrombosis, and pedicle kinking or torsion-may require unplanned surgical takeback and can result in flap failure. These events increase perioperative morbidity, expose patients to additional procedures, prolong hospitalization, and increase health care resource utilization. Preoperative identification of patients at increased risk of flap-related vascular compromise is therefore clinically important for surgical planning, patient counseling, and risk mitigation. The vascular reliability of DIEP flap is closely related to DIEP perforator morphology, including perforator length, diameter, muscle thickness, and other anatomic features relevant to flap perfusion. Computed tomographic angiography (CTA) has become an integral component of preoperative planning for DIEP flap breast reconstruction and is widely used to map perforator anatomy and guide perforator selection. However, CTA-based assessment remains largely descriptive, with emphasis on anatomic mapping and selection of dominant perforators. Few studies have translated CTA-derived DIEP perforator morphology into a standardized quantitative framework for risk stratification of flap-related vascular compromise and flap failure. We hypothesized that marked deviation of an individual's perforator anatomy from normative anatomic distributions may increase the technical complexity and unpredictability of flap harvest, intramuscular perforator dissection, and pedicle preparation. This deviation in DIEP morphology may predispose to intraoperative vascular traction, vessel injury, vasospasm, or suboptimal pedicle preparation, thereby potentially increasing the risk of early postoperative flap-related vascular compromise, subsequent unplanned surgical takeback, and flap failure. In this multicenter retrospective observational study, we will develop a CTA-based quantitative risk score, termed the DIEP Morphological Deviation Score (DIEP-MDS). Using a reference CTA cohort of individuals without breast cancer or reconstructive surgery, we will first establish reference distributions for key anatomic features relevant to DIEP perforator morphology, including length, diameter, and muscle thickness. We will then convert CTA-derived anatomic features into a standardized deviation score that quantifies the extent to which a patient's perforator anatomy differs from these reference distributions. In the internal surgical cohort, the study will assess whether higher DIEP-MDS values are associated with increased risks of flap-related vascular compromise requiring unplanned surgical takeback, as well as flap failure. The score will subsequently be externally validated in an independent multicenter surgical cohort. The study will pre-specify an analysis to assess whether a dual-pedicle strategy is associated with a lower risk of flap-related vascular compromise compared with a single-pedicle strategy across DIEP-MDS risk strata.