After the woman began experiencing unusual bleeding in 2012, the GP performed a smear test for her on both cervixes, finding the larger left cervix bled on being touched and had a lumpy appearance.
Two forms were then sent to the laboratory and the GP received a normal smear test result back, but there was nothing to indicate which cervix the result related to, or that there was another result still pending.
As the woman still had symptoms of bleeding, the GP sent a referral to a District Health Board gynaecology clinic.
The referral detailed the woman's cervical history, and she was placed on a waiting list with a "low" grading and a follow-up time of six months.
The DHB has since acknowledged that she was incorrectly graded and should have been categorised as semi-urgent, with a follow-up timeframe of one to three months.
The medical centre later received the second smear test result which was abnormal, however there were still no details about which cervix the test referred to and it was mistakenly marked as a duplicate.
The national screening unit wrote a letter to advise the woman of the abnormal result but she never received it.
Not wanting to wait for six months, she went to a private gynaecologist who diagnosed her with cervical cancer, and she underwent a hysterectomy.
Health and Disability Commissioner Anthony Hill has criticised the GP, medical centre, DHB and laboratory for their actions.
Mr Hill said the GP failed to discuss options of specialist involvement before the patient's symptoms began and should have realised there would be two results from the smear tests.
The medical centre was also criticised for not having adequate test result tracking systems, the DHB for incorrectly grading the patient, and the laboratory for not recording which sample each result related to.
Mr Hill has recommended that both the GP and medical centre provide a written apology to the woman and carry out a review of their processes.
The DHB was also required to carry out a review to ensure result reports clearly identified which cervix a report refers to in cases where patients have two cervixes.
Mr Hill also recommended that the national screening unit consider copying patients' doctors in on its correspondence regarding abnormal results, in order to provide a safety net.