He said women who initially didn't want an IUCD often changed their mind by the time an abortion took place.
"My mistake was to assume that this had taken place and that [the patient] had changed her mind and wanted to have an IUCD as the assistant nurse had opened an IUCD and placed it on the instrument trolley for me to insert at the end of the procedure," the doctor said. "In this case my assumption was incorrect as [she] had not consented for this to take place."
Health and Disability Commissioner Anthony Hill released a report about the events. The names of the patient, known as Ms A, and surgeon, Dr C, were suppressed.
"The IUCD was inserted in Ms A during a procedure at Epsom Day Unit in 2010, without Ms A's knowledge," Mr Hill said in his report.
"The presence of the IUCD was identified in 2013 after Ms A was unsuccessful in her attempts to become pregnant."
Mr Hill found the surgeon was at fault for assuming the patient consented to the IUCD. "In this case, the operating surgeon did not take reasonable steps to ensure that Ms A had given her informed consent to the insertion of the IUCD prior to inserting it."
But Mr Hill also found systems operating at the Epsom Day Unit in 2010 for checking of consent prior to IUCD insertion were inadequate.
Mr Hill said Auckland District Health Board (ADHB) breached the Code of Health and Disability Services Consumers' Rights.
This was because ADHB failed to provide services to the patient with reasonable care. The Health Board was also found liable for the operating surgeon's error.
In response to Mr Hill's investigation, the surgeon apologised to Ms A and Epsom Day Unit made several changes to its processes to try avoid repeating the error.
Mr Hill recommended that ADHB audit its new system, and arrange a records-based review for patients randomly selected for the first three months of 2010, 2012 and 2014. Mr Hill said such a review would "identify any inconsistencies apparent from the records of those patients".
The Health Board was also asked to report back to the Commissioner on the findings of those audits.
When the patient first complained, an ADHB staff member said she'd write an apology letter to the patient, but never did.
The patient told the Commissioner the incident caused her to suffer stress and disappointment each month when she did not become pregnant, and that she spent money on pregnancy vitamins, pregnancy tests, ovulation kits, doctor's visits and various other matters while trying to conceive.
Auckland DHB chief executive Ailsa Claire said: "We regret the distress caused to the patient involved and unreservedly apologise.
"Auckland DHB is taking the recommendations outlined in the commissioner's report very seriously and will be prioritising actions to address them.
"A number of changes have been made to the system since 2010, when the incident occurred, to improve processes and minimise the risk of such errors from happening again."
