Validation of a simple technique of volumetric analysis of complex incisional hernias without 3D CT scan reconstruction

Purpose Volumetric analysis is being increasingly utilized in the preoperative evaluation of complex incisional hernias. Three-dimensional (3D) reconstruction of abdominal computed tomography (CT) scan has been used to obtain surface area (SA) and volume (Vol.) measurements, while others have used simple mathematical formulas to obtain SA and Vol. estimates without 3D reconstruction. Our objective was to assess the correlation of SA and Vol. measurements and estimates of complex incisional hernias. Methods We conducted a retrospective agreement study of adults who underwent abdominal wall reconstruction from 2007 to 2018. Demographics, hernia characteristics, and operative data were collected from the medical record. SA and Vol. measurements were obtained after 3D CT reconstruction. Linear CT variables were obtained independently by two surgeons and SA and Vol. estimates were calculated. Because both surgeons reported similar results, only lead author values are reported in the abstract. We used Pearson's correlation coefficient (r) to assess inter-rater agreement and the agreement between SA and Vol. measurements and estimates. Results A total of 108 patients were eligible for analysis. The mean age was 57 +/- 11 years and 53 (49%) were female. 42 (39%) hernias were recurrent, 10 (9%) patients had a stoma, and 9 (8%) had a history of open abdomen. The mean defect width was 11 +/- 4 cm and mean defect surface area (DSA) was 150 +/- 95 cm(2). Inter-rater agreement of SA and Vol. estimates was high (r >= 0.80). There was high correlation between SA and Vol. measurements and estimates for DSA, hernia sac volume (HSV), abdominal cavity volume (ACV), and HSV/ACV ratio (r = 0.81, 0.89, 0.94 and 0.91, respectively). Conclusion SA and Vol. estimates demonstrated high level of agreement with SA and Vol. measurements using 3D reconstruction. SA and Vol. estimates can be obtained using simple mathematical formulas using easily obtained linear variables negating the need for the time and effort consuming 3D reconstruction.