右腎 is read as うじん (ujin) and means right kidney.
うじん
ujin
みぎがわ
right side
うよく
right wing (in soccer, rugby, etc.)
みぎて
right hand
みぎ
right
みぎうで
right arm
みぎはし
right end
うせつ
turning to the right
うは
right wing
うほう
みぎあし
right foot
うおうさおう
moving about in confusion
うちゅうかん
between right and center fielders (centre)