THEORETICAL KIDNEY VOLUME VERSUS REAL KIDNEY VOLUME - COMPARATIVE-EVALUATION IN FETUSES

In order to present equations and normal growth curves of the theoreti cal kidney volume we studied 290 kidneys taken from 145 fresh human fe tuses ranging in age from 13 to 36 weeks post-conception (WPC). The ki dneys were evaluated in terms of greatest longitudinal length (L) supe rior pole width (SW), inferior pole width (IW), thickness (T) and real volume (RV). The theoretical kidney volume was calculated (ellipsoid formula: volume = length x width x thickness x 0.5236) by using SW, IW and the arithmetic mean between SW and IW. The assessment of the theo retical volume by using IW was well correlated with the real kidney vo lume. We found no statistically significant difference between right a nd left kidneys. During the second trimester (13 to 24 WPC) there was no difference in kidney volume between male and female fetuses. In the third trimester (25 to 36 WPC) male fetuses presented kidney volumes significantly greater than female fetuses. To evaluate the theoretical kidney volume in fetuses, one may use the IW, which is a quickly and easily obtained measurement. During the second trimester one may monit or the fetal kidney using equations and growth curves without taking t he fetal sex into account. During the third trimester the fetal kidney volume must be evaluated using specific curves for male and female fe tuses.