A woman had a gauze swab left insider her for days because of lack of communication during surgery.
A report by the Health and Disability Commissioner has found poor communication, unclear policy and staff unsure of their responsibilities contributed to the error.
In 2017, the woman had cysts removed from her vagina and uterus, but four days later she reported feeling "extremely unwell" and discovered a piece of surgical gauze had been left inside her.
"When I went to the toilet it felt like a part of me was falling out of my vagina and I was scared," she said.
It was then the doctor realised it was possible that a piece of gauze was left inside the patient and asked her to remove it, which she did.
The doctor then arranged to examine and treat the woman.
In the report by the Health and Disability Commissioner Anthony Hill, he said the theatre nurses did not properly count the swabs and tools before and after the procedure, and that no record of the gauze being inserted was made.
He found "communication was ineffective or non-existent at key points of the surgery, staff did not work together as an effective team, the count policy lacked detail, and staff members were non-compliant with the count policy".
For these reasons the commissioner said the medical centre did not provide the woman with reasonable care and skill thus breaching her rights.
But he said it was ultimately the surgeon's responsibility to ensure the policy was followed.
The surgeon said it was an "isolated, genuine mistake" and there "were systemic issues which contributed to the error occurring."
Mr Hill recommended the medical centre and surgeon provide a written apology to the woman and audit its count policy.