Attempted Suicide & Disclosure

A patient entered the dental operatory wearing a short-sleeved blouse that revealed a bandage around the anterior cubital of her right arm. During the health history interview, the hygiene student questioned the patient about the bandage. The patient revealed that she had cut her brachial artery during a recent suicide attempt. Since this and other information obtained did not contraindicate treatment, the student performed a class I prophylaxis. The appointment proceeded well. The patient seemed normal, relaxed and cheerful. After the patient was dismissed, the student noticed a blue journal on the counter. She opened it to reveal a psychologist's name, address and phone number. She continued flipping through the journal, soon realizing it was her patient's diary of daily thoughts. Instead of closing the journal and calling her patient to let her know she had left it behind, the student continued to read the entries. One such entry indicated that her patient planned to attempt suicide again that following weekend since her roommate planned to be away, thus leaving her alone in the apartment. The hygiene student became very concerned and frightened.

What should she do? What would you do? What ethical principles were violated, if any? Should confidentiality be breached? Does our present "Code of Ethics" guide us?