A patient in New Zealand was given several unnecessary doses of chemotherapy after doctors misdiagnosed her with breast cancer.

A doctor's incorrect diagnosis of a biopsy meant a New Zealand patient had to go through several doses of chemotherapy for no reason.

Northland District Health Board patient had a biopsy test and the results of it were reported incorrectly, meaning the patient underwent the treatment unnecessarily.

The incident was one of 454 serious adverse events reported by hospitals around New Zealand for the year to June in a Health Quality and Safety Commission report released on Thursday.

The incidents include patients being stitched up with medical equipment still in their body and being given the wrong medical treatment.

One Auckland District Health Board patient was put under anaesthetic for hernia surgery, but before surgeons began operating, they realised the patient was only in for dental surgery.

Another Auckland patient had an unnecessary renal biopsy after the doctor selected the wrong name on an electronic clinic list.

The number of adverse events are up on last year and have more than doubled since the reports began in 2006-2007.

But the commission says this is due to better reporting of events rather than an increase in the serious incidents occurring.

Most of the incidents were falls, with 248 reported around the country - and in 98 cases a patient suffered a broken hip.

The clinical lead of the report, Sandy Blake, says DHBs are working to reduce the rates of falls and says the first step is treating and assessing bone health properly.

WHAT WENT WRONG
* 248 suffered serious harm in a fall
* 28 patients had a delay in treatment
* 16 patients were affected by incorrect process including an unnecessary procedure, and incorrect procedure or a procedure meant for someone else
* 30 people were given the wrong medicine, the wrong dose, administered the wrong way or had an adverse reaction to their medicine
* 11 patients had items left inside them including swabs, a needle and surgical equipment

OTHER SEVERE INCIDENTS
* Patient waited 150 days to be treated by a specialist for skin cancer, Waitemata
* Doctors performed a bone marrow transplant on identical twins they believed were non-identical, raising the risk of cancer returning, Auckland
* Patient given 10 times the amount of a drug they needed, required blood transfusion, Auckland
* Sperm incorrectly thrown out, despite it being stored for fertility samples, Auckland
* Patient needed to be resuscitated after inadvertently being given muscle relaxant through an IV line which hadn't been flushed, Counties Manukau
* Surgical instrument left in patient during surgery, MidCentral
* Patient given more medication than they needed, suffered a stroke and died, Capital and Coast
* Part of a stapler left in a patient's pelvis after emergency bowel cancer, Capital and Coast
* Wrong organ removed during surgery, Southland

Source: Health Quality and Safety Commission serious adverse events report, 2014

Copyright AAP 2014.