Reference ranges of kidney dimensions in term newborns: sonographic measurements

Abstract

Ultrasonographic measurement of kidney dimensions is important in evaluation of renal disease during the neonatal period, when renal abnormalities are common and renal size rapidly changes with age.

To determine the reference ranges of kidney dimensions in newborns and to provide a reference chart for daily practice.

In this prospective study, kidney dimensions were evaluated in 385 healthy newborns with a gestational age a parts per thousand yen37 weeks. Each neonate seen at an obstetrics clinic and neonatal intensive care unit was examined with sonography within the first week of life. Relationships of all dimensions with gender, gestational age, height and weight were statistically analyzed.

All dimensions of the kidneys were smaller in girls than in boys (P < 0.05). The dimensions of the left kidney were larger than those in the right kidney in both genders (P < 0.01). Longitudinal and anteroposterior dimensions of the right and left kidneys showed no correlation with the gestational age in either gender. The dimensions correlated with the height in boys (P < 0.01), while no correlation was seen between the dimensions and height in girls (P < 0.05). Weight had the best correlation with all dimensions in both genders.

The reference values of kidney lengths and diagrams from this study may be useful in the sonographic evaluation of kidneys in newborns.