A damning report by the Health and Disabilities Commissioner has recommended an audit of the services provided by the country's top abortion clinic.
It comes after a woman complained she had a long-term contraceptive device inserted in her uterus without her consent at the time of an abortion in 2010.
The woman, whose identity is protected, only discovered the intrauterine contraceptive device after going for medical tests when she tried repeatedly and was unable to fall pregnant three years later.
Investigation by the Health and Disability Commissioner has found a doctor at the Epsom Day Clinic mistakenly inserted the contraceptive device (IUCD) without the woman's consent.
It found that to be in breach of the patient's rights.
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The doctor has also been found to have failed in his duty of providing health services with "reasonable care and skill".
Over 800 women have their pregnancies terminated at the Epsom Day Clinic each year. In the report the way in which staff at the clinic deal with the high turnover of patients is likened to a 'conveyor belt' .
The doctor who performed the termination told the Commissioner he performs up to 10 procedures a day and cannot recall the specific patient concerned.
However he said an IUCD was placed on the instrument trolley during the operation and was therefore inserted. Because of this he told the Commission he believed the woman had given her consent.
The doctor also said he tells his patients during the procedure if he is inserting contraception, but at this time they are usually sedated.
In a statement the Auckland District Health Board has "unreservedly" apologised for the error. It says it is taking the recommendations in the Commissioners' report very seriously.
It's made a number of changes since the complaint, including written consents, and doctors now obtains a signature of consent from their patients before inserting an IUCD.
The report, though, says the ADHB refused to admit their consent system was inadequate at the time of the error, citing "insufficient evidence".
It says there is "no suggestion" the clinical treatment provided was of concern and that the complainant suffered "no physical injury or permanent harm".
The Health and Disability Commissioner requested patient records detailing when a device had been inserted without consent.
The Auckland District Health Board responded that it kept no searchable record.
The Health Board told the Commissioner it would not be possible to ascertain cases where the patient did not receive the treatment she consented to, without a case by case review of tens of thousands of cases.
As written consent had not been previously required, a search would not reveal conclusively whether or not consent had been given.
The Auckland District Health Board says it believes it can measure its errors on the basis of complaints and there have been "not more than three in a decade".
A third party audit of the ADHB's systems has been recommended, from patients selected randomly from the first three months of 2010, 2012 and 2014.
An audit of the system the clinic uses to ensure the correct procedure is performed on the correct patient has also been recommended. The ADHB is required to report back within three months.