A man has been found guilty of GBH after he hit a four-year-old girl so hard he nearly killed her.

The girl, who cannot be identified for legal reasons, was admitted to St George’s Hospital where a large team of experts cut open her abdomen and operated for several hours trying to find out what was wrong.

During the operation on Tuesday, March 26, 2013, a surgeon told the girl’s mother it looked like they were going to lose her, at which point the mother was described as sinking, screaming silently, Kingston Crown Court heard.

Doctors discovered a blow to the stomach had caused two holes in part of her intestine and two litres of fluid had leaked out of her bowel and surrounding organs.

The injury was described by medical experts as so rare they had to refer to literature. They estimated the trauma would have taken place within 48 hours of her arriving in hospital.

The little girl, from Tooting, spent a month in hospital and was placed in a foster home on release.

The girl’s mother was arrested along with her ex-boyfriend, her housemate and housemate’s boyfriend.

The jury saw a video of the little girl being questioned about her stomach pain, in which she gave different answers about why she had gone to hospital, including eating too many sweets.

When asked directly if her mother’s boyfriend hurt her, the girl replied “yes” and “he punched me”.

Her foster carer also told the court the girl made a punching movement in her stomach.

The mother’s ex-boyfriend was found guilty of grievous bodily harm with intent on October 24.

The three other defendants, the mother, flatmate and flatmate’s boyfriend, were cleared of causing or allowing the little girl to suffer physical harm.

The flatmate’s boyfriend, who was at work on the day the injury was inflicted, was acquitted early in the trial on instruction of the judge. The flatmate was acquitted by the jury. She had gone to bed the previous night and only realised something was wrong with the little girl when she went into the mother’s bedroom on the Monday morning.

The mother was also acquitted by the jury and told the court: “There’s no way I thought anyone had assaulted [her]. If I thought that I would call the police because she was the most important person to me.”

Over the Sunday night the mother’s ex-boyfriend shared her bed, while the little girl slept in the same room on another bed. He was accused by the prosecution of hitting the little girl, who often liked to sleep in her mum’s bed.

The ex-boyfriend is due to be sentenced on November 18.