Since eggs are candled, do they still need to be checked for blood spots?

Blood spots in fertilized eggs are prohibited, and one should check cracked eggs to make sure they are blood-free. Commercial eggs today are not fertilized and blood spots are not halachically prohibited.

Nonetheless, even today, the prevailing minhag (custom) is to discard eggs with blood spots and check cracked eggs before they are cooked. Though raw eggs are candled before they are packaged, the candling process is not foolproof and the OU cannot guarantee that the eggs are 100% free from blood spots. The presence of an OU on a box of eggs does not obviate the need to check the individual eggs for blood spots. OU supervision is limited to the method of processing the raw egg. For example, raw eggs are sprayed with mineral oil to coat the egg shell with sheen and clog the pores to enhance the shelf life of the egg.