A Cross-Sectional Study of Adult Inguinal Hernial Orifice Diameter Estimation by Computed Tomography

[Purpose] This study aimed to determine an optimal method for estimating adult hernial orifice diameter using computed tomography (CT) performed with the patient in the prone position to achieve inguinal decompression of the hernia (CT hernia study).[Methods] Fifty-four adult patients with inguinal hernia underwent laparoscopic hernia repair by transabdominal preperitoneal patch technique. Before surgical manipulation, we measured actual hernial orifice diameters in these patients. All patients underwent surgery after the CT hernia study became the standardized form of preoperative imaging for adult inguinal hernia patients in 2006 at St. Marianna University Hospital. We calculated the estimated hernial orifice diameter using four formulas for external inguinal hernias (Type I) and two formulas for internal inguinal hernias (Type II). Then, based on the preoperative images, a linear univariate regression model was created for the four type I estimation formulas by defining the estimated values as explanatory variables (X) and the actual hernial orifice diameters as objective variables (Y).[Results] A significantly positive correlation was observed between all estimation models using preoperative diagnostic imaging and actual hernia diameter measurements in the adult patients. The most effective formulas were the estimation method mimicking 3D imaging (length of a line connecting the medial pole of the inferior epigastric artery and internal margin of the external iliac artery in the same transverse image) for type I hernias and the sagittal image method (maximum length of a line connecting the superior and inferior ends of the hernia sac [intraperitoneal tissues] projecting outside the transversalis fascia line in a sagittal image) for type II hernias.[Conclusion] CT hernia studies that mimic 3D reconstruction in type I hernias and use sagittal images for type II hernias may be a useful method for estimating hernial orifice diameters in adult patients.