Size and location of the kidneys during the fetal period.
OBJECTIVE
The aim of this study was to determine the morphometric development and location of the kidneys during the fetal period.


METHODS
Three hundred and forty-four fetal kidneys, obtained from 172 human fetuses and aged between 9 and 40 weeks, were used in this study. Fetuses were divided into four groups according to the gestational weeks: first trimester, second trimester, third trimester, and full-term gestation. First, the anterior abdominal wall was dissected. Topographic localization of the kidneys in the abdominal cavity was then assessed. The distance between the inferior pole of the kidney and iliac crest was measured. The vertebral levels of the superior and the inferior poles and relations to ribs of the kidneys were determined. The distances between hilum of the kidneys and inferior vena cava, abdominal aorta, and midline of the vertebral column were determined. The dimensions (width, length, and thickness), weight, and volume of kidneys were measured.


RESULTS
The results showed that the distance between the inferior poles of the kidneys and the iliac crest increases with gestational age. The vertebral levels of the superior and inferior poles of the kidneys increased during the fetal period. The level of the left kidney was higher than the level of the right kidney in the fetal period. The posterior surface relations to the ribs showed certain ascendance during gestation, corresponding to vertebral levels. However, fetal kidneys do not reach the same level as adults at full term. The kidneys move farther apart from the midline of the body during the fetal period. The dimensions, weight, and volume of the kidneys increased with gestational age during the fetal period. The ratio between kidney weights and fetal body weights were determined, and we observed that the ratio decreased during the fetal period. There were no sex or laterality differences in any parameter.


CONCLUSIONS
The morphometric parameters and the location of the fetal kidneys were determined by the present study. This will also contribute to imaging of fetal kidneys and detection of kidney abnormalities in the intrauterine period. We hope that the present results can provide some useful findings for radiological (ultrasound and MR) studies.
Department of Anatomy, Faculty of Medicine, Suleyman Demirel University, Isparta, 32260, Turkey. osmansulak@yahoo.com
Osman
O
Sulak
Gülnur
G
Ozgüner
Mehmet Ali
MA
Malas
D001012:Aorta, Abdominal / Q000196:embryology; D005260:Female; D005865:Gestational Age; D006801:Humans; D007085:Ilium / Q000196:embryology; D007668:Kidney / Q000196:embryology*; D008159:Lumbar Vertebrae / Q000196:embryology; D008297:Male; D009929:Organ Size; D011247:Pregnancy; D012272:Ribs / Q000196:embryology; D014682:Vena Cava, Inferior / Q000196:embryology