A more thorough explanation:

A foreign object is something that is found in a place where it doesn't belong. This can include an item that is accidentally left inside a person's body during surgery, such as a sponge or surgical instrument.

For example, if a patient undergoes surgery and a surgical instrument is accidentally left inside their body, it is considered a foreign object. This can cause serious health complications and may require additional surgery to remove the object.

The discovery rule is often used in medical malpractice cases involving foreign objects. This rule allows the statute of limitations to be extended if a foreign object is discovered at a later time.