Bosses at Aberdeen Royal Infirmary have been accused of “significant failings” over the operation and told it must never happen again.
The woman, who had already endured treatment for breast cancer, was left “devastated” by the reconstructive surgery which she claimed was rushed.
The hospital said it was “deeply sorry” for the bungled surgery and that it accepted all the recommendations made in a report by the Scottish Public Services Ombudsman (SPSO).
The ombudsman, Jim Martin, investigated a complaint by the woman, referred to as Mrs C.
Mrs C said she was left with one nipple twice the size of the other and pointing in the wrong direction, as well as an infection in one breast.
The patient said her surgeon – referred to as Consultant 1 – was changed at the last minute when she went to the hospital for surgery in March 2011.
Mrs C had been treated for breast cancer the previous year.
She was supposed to undergo a lateral mammaplasty on her right breast along with symmetrisation surgery on her left breast.
But the new surgeon changed the surgery to her right breast, and she said she was only given a consultation 45 minutes before the operation.
A report from the SPSO said: “She described that her breasts were completely different shapes, that her right nipple was twice the size of the left, and that it pointed to the ground. She developed an infection in one breast.
“A scar on the other breast re-opened and required to be packed and dressed by a nurse regularly.
“Consultant 1 said it would require time for the swelling to go down before the final results of the surgery could be assessed.”
Mrs C initially complained to the health board, but was unhappy with the response she received.
The report added: “Mrs C remained dissatisfied and brought her complaints to my office on 19 July 2011. She explained that the impact upon her both physically and psychologically as a result of her experiences was devastating.
“She wanted to ensure no future patients went through a similar experience.”
Mrs C said she was left “completely floored” by the last-minute change, which meant a more junior member of staff carried out the operation.
Almost 100 grams of tissue were removed from her right breast, and 250 grams were removed from her left breast.
The report continued: “The long term impact of this experience upon Mrs C, particularly given the sensitive nature of this type of surgery, should not be underestimated.
“I understand Mrs C is seeking an opinion regarding further potential treatment and surgical options from another NHS Board.”
The ombudsman found it was unreasonable to change the surgeon and the surgical procedure at such short notice.
Ombudsman Mr Martin ordered the health board to apologise to the woman, who he said suffered a “difficult and upsetting experience.”
He upheld Mrs C’s complaint that the outcome of the surgery was unacceptable.
An NHS Grampian spokeswoman said: “We have read the report, accept all the recommendations contained within it and will be carrying out all the actions required.
“We are deeply sorry for the level of distress suffered by Mrs C and we will be writing directly to her to make a full apology.
“We do not comment on individual staff members, whether past or present.”
A spokeswoman for Patient Concern said: “It’s ludicrous, where was the informed consent in that process?
“It’s particularly bad to go through this after having breast cancer.
“People need to be treated properly at such a time, but unfortunately you’re just dumped on a conveyor belt.
“It’s extremely depressing, but it’s such a common story with complaints.
“I hope she gets compensation.”