"The nurse realised her mistake immediately but allowed the woman to go home without informing her of the needle-stick error."
She also failed to assess the woman's blood pressure and weight, but documented that she had done so.
The following day the nurse told the practice manager of the error and was told to inform the woman and the woman's GP.
The nurse did not do so and then went on leave for four days.
When the nurse returned to work she informed the GP, the report said.
The patient was immediately contacted and blood tests taken. They all came back negative.
Ms Baker found that the nurse breached the code in several respects, including failing to provide services with reasonable care and skill by reusing a needle from another patient; and by not notifying the woman of the mistake promptly she did not provide her with the information that a reasonable consumer would expect to receive.
"[The nurse] is an experienced practice nurse. In this case she let down [the patient] by not following safe practice in the administration of Depo-Provera, leading to the needle-stick injury, and also by her actions after the error," Ms Baker said.
"I consider [the nurse] should have appreciated the potential gravity of the needle-stick error and not waited five days before making further attempts to discuss the matter with [the GP]."
The nurse would be referred to the Nursing Council of New Zealand with the recommendation that she undergo a competency review, the HDC said.