Renal Variants

comensatory hypertrophy

Enlargement of the unaffected contralateral kidney with unilateral renal agenesis or compromised renal function

dromedary hump

Bulge on the lateral border of the kidney (often on the left kidney)

dupex (duplicated) collecting system

Division of the renal sinus. In this variant, there are two separate renal sinuses; they are referred to as an upper pole moiety and lower pole moiety Obstruction to one or both of these collecting systems can occur Two ureters drain separate portions of the kidney Kidney with duplex collecting system will typically measure longer than a normal size kidney

the most common congenital anomaly of teh urinary tract

duplex collecting system

ectopic kidney

Pelvic kidney: one or both kidneys may be located within the pelvis; the pelvis is the most common location of an ectopic kidney Crossed fused ectopia: both kidneys are fused and on the same side of the body Thoracic kidney: kidney sits partially or completely in the chest

extrarenal pelvis

The renal pelvis is located outside of the renal hilum

fetal lobulation

Lobulated or bumpy outline to the kidney(s); can be seen in adults

horseshoe kidneys

Two kidneys that cross the midline and connect at their lower poles by an isthmus The isthmus of the horseshoe kidneys travels anterior to the abdominal aorta and inferior vena cava

hypertrophic column of bertin

Enlargement of a renal column seen as an indentation of the renal sinus Actually are double layers of renal cortex

junctional parenchymal defect (junctional line)

Results from the incomplete fusion of the two embryologic components (renunculi) of the kidney Appears as a hyperechoic, wedge-shaped structure on the anterior portion of the kidney; located between the upper and middle sections of the kidney

malrotated kidney

The kidney sits in the renal fossa but is positioned off of the normal axis

renal agenesis

Congenital absence of the kidney. Bilateral renal agenesis is typically not consistent with life

renal hypoplasia

The underdevelopment of the kidney in which there are too few nephrons Kidney will be smaller than normal

renal sinus lipomatosis

Excessive fat within the renal pelvis

Renal sinus will be large and echogenic

supernumerary kidney

A third, smaller kidney

Duplex collecting system. Sagittal image of the right kidney (RK) revealing two distinct renal sinuses (arrows), separated by a band of parenchyma, denoting a duplicated collecting system.