Ultrasonic evaluation of kidney volume in term and preterm infants.

Kidney volume in relation to gestational age, birthweight, and height was determined in 121 infants, 58 females and 63 males, with gestational ages from 23 to 43 weeks (mean, 33.3) and birthweight from 430 to 4600 gm (mean, 1982 gm). The kidney volume was measured using a real-time linear computed ultrasound scanner, with a 5 MHz transducer. The renal volume was calculated from outer kidney diameters using the volume formula for an ellipsoid. In the infants studied, mean volume of the right kidney was 6.0 ml (range, 1.4 to 13.8 ml), and of the left kidney 6.6 ml (range 1.5, to 15.6 ml), with no significant difference. A highly significant correlation was found between the volume of both kidneys and either gestational age, or birthweight, or height, with r values ranging from 0.81 to 0.92. The best correlation was observed with birthweight. No significant difference was found between males and females.