A Hawke's Bay woman sitting in the back seat as her partner drove along a rural road stabbed him in the back with a knife through the car seat, in an attack that eventually left him unconscious.

Desiree Patricia Heta , 38, pleaded guilty in the Hastings District Court on Tuesday to a charge of wounding with intent to injure on her partner of 10 years.

On May 3 this year, Heta and her partner were travelling along Te Mata-Mangateretere Rd to visit a friend in Waimarama.

Heta's partner was driving the car and she was sitting directly behind him in the rear passenger seat.

The pair began to argue, with her partner "becoming verbally abusive and putting the defendant down", the summary of facts said.

An angry Heta picked up a large, black-handled knife from the seat beside her and began slashing the rear of the driver's seat.

The knife eventually slashed through the seat and stabbed her partner causing "a large wound to his back which bled profusely".

Despite the knife wound, her partner kept driving and the pair carried on arguing all the way to Waimarama, where he was treated for his wounds at his friend's address.

He eventually lost consciousness and an ambulance was called for further treatment.

The slashing of the knife resulted in a large wound in the centre of his back which required "multiple stitches". Police were still waiting for a report from Hawke's Bay Hospital on the extent of the injuries at the time of the court appearance.

Heta told police that she was tired of being put down by her partner all the time which resulted in her "getting really angry".

Her defence counsel said "it was a very unfortunate incident" and after a long history of domestic violence his client "finally snapped".

Judge Bridget Mackintosh remanded Heta on bail and she will be sentenced in July.