Y would us of spleen be normal, and ct spleen measure 13cm ,liver 17cm on us and 19 cm reidel lobe on ct..doc not worried about spleen .should i be?

U/S is freehand: U/S is sometimes limited by operator skill and persistence. Also maximum dimensions can be hard to get since only so many angles are available to the sonographer. CT is more complete to see the anatomy and can be most accurate for organ volume esp. by 3D measurement. Reidel's lobe is normal, see pic. Mild splenomegaly needs clinical correlation, so its significance "depends".