Volume calculation of rats' organs and its application in the validation of the volume relation between the abdominal cavity and the hernial sac in incisional hernias with 'loss of abdominal domain'

BACKGROUND: The calculation of the volume ratio between the hernia sac and the abdominal cavity of incisional hernias is based on tomographic sections as well as the mathematical formula of the volume of the ellipsoid, which allows determining whether this is a giant hernia or there is a "loss of domain". As the images used are not exact geometric figures, the study of the volume of two solid organs of Wistar rats was performed to validate these calculations. AIM: To correlate two methods for determining the volume of the kidney and spleen of rats, comparing a direct method of observation of the volume with the mathematical calculation of this value. METHODS: The volume of left kidney, geometrically more regular, and spleen, with its peculiar shape, of ten animals was established in cubic centimeters after complete immersion in water with the aid of a beaker graduated in millimeters. These values were compared with those obtained by calculating the same volume with a specific mathematical formula: V = 4/3 × π × (r1 x r2 x r3). Data were compared and statistically analyzed by Student's t test. RESULTS: Although the average volume obtained was higher through the direct method (1.13 cm3 for the left kidney and 0.71 cm3 for the spleen) than the values calculated with the mathematical formula (0.81 cm3 and 0.54 cm3), there were no statistically significant differences between the values found for the two organs (p>0.05). CONCLUSION: There was adequate correlation between the direct calculation of the volume of the kidney and spleen with the result of mathematical calculation of these values in the animals' studies.