Dreaming of operation is both positive and negative sign as per dream meaning and interpretation. The dream means soon you will face an intense situation in life. It also means hospital related visits or sudden health problem resulting in an immediate medical intervention. Dreams of operation also are a warning sign about a problem in near future.
Dreaming of operation and you are not seen in the dream means you will face difficulties while you are away from home. It also means some kind of trouble to a family member or friend.
Dream of operation and you are seen in the dream means you will have to show courage and strength. The dream is asking you to be mentally prepared to face an adverse situation.
Dreams of operation and you see too much blood or organs or body opened up means you will witness something gory. It also means getting into legal tangle as you are a witness to a crime.
Please note that watching operation or reading or talking about it during daytime and then having the dream has no meaning. If the dream happens without any daytime influence then it has a meaning.