During grading, eggs are passed over a strong light in a process known as candling. This method helps identify various issues, including blood spots. The likelihood of blood spots being present in brown eggs is slightly higher because their darker shells make it harder to detect them during grading. While candling methods, including electronic spotters, can reveal most eggs with blood spots, it is impossible to catch them all.
Blood spots occur when a blood vessel ruptures in the hen during egg formation or within the oviduct. This is a natural process, and the hen is not harmed. Eggs with blood spots are both chemically and nutritionally safe to eat. If the spot is small, it can be removed with the tip of a knife before cooking, if desired. However, if the rupture is large, it is not harmful but may not be appetizing, and in that case, the egg should be discarded.