The mark of a successful Phowa is that after death, there is visible hair loss, a bump or some yellow liquid seeping around the vertex. These marks serve as proof of successful rebirth. If these symptoms are present, the subsequent guide for the practice of the intermediate state will no longer be needed. If not, the guru or dharma friends will need to provide guide for the practice of the intermediate state.

~Depicted from THE HANDBOOK'S FOR LIFE JOURNEY - On Death And Rebirth-How to Face Death