Have been diagnosed with blighted ovum shud I wait for miscarriage or should go for d &c?

Difficult. There are pros and cons of each. Waiting is the most natural choice. It may take 2 weeks or longer before bleeding begins and then it may last 2 weeks or longer and be painful. A D&C does carry risk of both the procedure and the anesthesia. Psychologically many women prefer the D&C so that it will be over and they can begin the healing process. You should take your time and decide whats best.