Human fetal compensatory renal growth.

The occurrence of prenatal compensatory renal growth has remained in question, despite the general acceptance of this phenomenon postnatally. We measured by ultrasound imaging the renal length of 22 human fetuses with a solitary kidney or contralateral multicystic dysplastic kidney, and compared it to measurements in 40 normal control fetuses. Renal length was normalized to fetal biparietal diameter. Analysis of covariance showed that the solitary kidneys were significantly larger than normal controls (p < 0.0001), although the rate of growth was not significantly increased above normal. These data document the presence of compensatory renal growth in human fetuses with solitary or functionally solitary kidneys.