Estimation of Hemi-Abdominal-Based Free Flap Weight Using Two Computed Tomography-Derived Measurements

Nicolas Greige, Bryce Liu, David Nash, Katie E. Weichman, Joseph A. Ricci

Research output: Contribution to journalArticlepeer-review


Background Accurate flap weight estimation is crucial for preoperative planning in microsurgical breast reconstruction; however, current flap weight estimation methods are time consuming. It was our objective to develop a parsimonious and accurate formula for the estimation of abdominal-based free flap weight. Methods Patients who underwent hemi-abdominal-based free tissue transfer for breast reconstruction at a single institution were retrospectively reviewed. Subcutaneous tissue thicknesses were measured on axial computed tomography angiograms at several predetermined points. Multivariable linear regression was used to generate the parsimonious flap weight estimation model. Split-sample validation was used to for internal validation. Results A total of 132 patients (196 flaps) were analyzed, with a mean body mass index of 31.2 ± 4.0 kg/m 2 (range: 22.6-40.7). The mean intraoperative flap weight was 990 ± 344 g (range: 368-2,808). The full predictive model (R 2 = 0.68) estimated flap weight using the Eq. 91.3 x + 36.4 y + 6.2 z-1030.0, where x is subcutaneous tissue thickness (cm) 5 cm lateral to midline at the level of the anterior superior iliac spine (ASIS), y is distance (cm) between the skin overlying each ASIS, and z is patient weight (kg). Two-thirds split-sample validation was performed using 131 flaps to build a model and the remaining 65 flaps for validation. Upon validation, we observed a median percent error of 10.2% (interquartile range [IQR]: 4.5-18.5) and a median absolute error of 108.6 g (IQR: 45.9-170.7). Conclusion We developed and internally validated a simple and accurate formula for the preoperative estimation of hemi-abdominal-based free flap weight for breast reconstruction.

Original languageEnglish (US)
Pages (from-to)549-554
Number of pages6
JournalJournal of reconstructive microsurgery
Issue number7
StatePublished - Sep 13 2022


  • DIEP
  • TRAM
  • breast reconstruction
  • flap weight estimation

ASJC Scopus subject areas

  • Surgery


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