NEONATAL KIDNEY --USG

1.The sonographic appearance of the kidneys in the neonate differs from that in older children in respect of  

a.more lobulation

b.much less renal sinus echogenicity

c..very echogenic cortex

d.CM differentiation extremely well

e.cortex thicker relative to the size of  pyramid

ans 1.e

 Neo­nates have much less renal sinus fat than in older children, and the central renal sinus echogenicity is uncommonly appreciated at this age.

The immature neonatal cortex is very echo­genic; in contrast to that in older children, it is hyperechoic relative to the liver—even more so in premature neonates. Because of this, sonography depicts corticomedullary differen­tiation extremely well .Postnatally, the echogenicity of the cortex gradually decreases, and it is usually hypoechoic relative to the liver by 4 months of age, but occasionally this process takes until 6 months.

 Normal renal pyramids are hypoechoic relative to the renal cortex, indepen­dent of patient age, and are more echogenic than normal urine in the collecting system, which is anechoic .

Compared with the cortex in older children, the immature cortex in the neonate is thinner relative to the size of the pyramids. Therefore, the pyramids appear relatively large .

To those unfamiliar with this normal neonatal ap­pearance, the relatively large, normal, hypoechoic pyramids may be misinterpreted as dilated calices or renal cystic disease and the relatively thinner hyperechoic cortex may be misinterpreted as cortical scarring or even ischemic changes.

Figure . Normal sonographic appearance of the renal pyramids in young infants. (a) Transverse sonogram of a neonatal kidney shows good corticomedullary differentiation. The hypoechoic pyramids normally appear

relatively large at this age. (b) Focused longitudinal sonogram of a kidney, obtained with a linear-array transducer,

shows striations of the parenchyma, which are better appreciated in the cortex than in the pyramids.

The echogenic structures (arrows) represent the collapsed fornices of the calices (which are not distended with urine) together with some renal sinus fat. 

REF --RADIOGRAPHICS