Validation of the triangular prism method using computed tomography to estimate DIEP flap weight in routine clinical practice – a St Andrew free flap audit registry study

A total of 164 DIEPs were recorded, and complete data were available for 119 DIEPs (73%). The mean estimated flap weight was 979 g (range: 251-2,125, SD [standard deviation] 448), and the actual flap weight was 937 g (range: 303-2,792, SD 461). The Bland-Altman plot showed that the estimated weight overestimated the actual weight by an average of 41 grams. However, the LOAs of -530 and 614 grams far exceed the a priori set limits of maximum acceptable difference (100 grams) between the estimated and the actual flap weight. Further studies are needed regarding how the triangular prism method can be combined with clinical measurements to become an easily used and reliable tool.