Prenatal compensatory renal growth: documentation with US.

PURPOSE

To determine whether compensatory renal growth (CRG), which occurs in adults, children, and infants after loss of functioning renal tissue, occurs in fetal life.

MATERIALS AND METHODS

Prenatal ultrasound scans were used to select 29 patients with a unilateral multicystic dysplastic kidney and four patients with unilateral renal agenesis. Accurate measurements of prenatal renal length were obtained in 21 of these patients; an accurate measurement of postnatal renal length and birth weight was obtained in 27 of these patients. Prenatal and postnatal renal measurements of the contralateral kidney were compared with renal length in 23 matched control patients and previously reported normal renal lengths.

RESULTS

The single functioning kidneys in the study patients were significantly longer than those in the control patients before and after birth (P = .001).

CONCLUSION

This study provides strong evidence to support the belief that CRG occurs before birth.