右腎 is read as うじん (ujin) and means right kidney.
うじん
ujin
うそく
right side
うよく
right wing (in soccer, rugby, etc.)
みぎて
right hand
みぎ
right
うわん
right arm
うたん
right end
うせつ
turning to the right
うは
right wing
うほう
right foot
うおうさおう
moving about in confusion
うちゅうかん
between right and center fielders (centre)