Nine-year-old Leila died days after falling off a swing and her family doesn't know why.

When nine-year-old Leila Baartse-Harkin fell off a swing in September last year her parents couldn’t have imagined the tragedy that awaited them.

Leila’s Adelaide Hills parents took her to hospital for the abdominal complaints and vomiting she was suffering on September 29 2015, but she was later discharged.

Two days later their daughter died, of what an autopsy revealed was peritonitis due to a perforated small bowel.

Now, doctors, her family and the courts are trying to find out what went wrong.

At an inquest into her death, which began last year, the court has today heard that a junior doctor who treated Leila believed her condition worsened after she was released from hospital, The Adelaide Advertiser reports.

Leila had jumped off a swing and fell on her stomach at Eastern Fleurieu School after-school care.

She was later complaining of stomach pains, vomiting and was unable to lie down as her ‘stomach was hurting’, according to her mum Edie Harkin.

Her parents took her to Strathalbyn Hospital, and from there she was sent to the Women’s and Children’s Hospital.

Women’s and Children’s Hospital registrar Dr Amy McMellon sent Leila for x-rays, noting she had a rigid abdomen and an elevated heart rate, but said those scans did not indicate internal injuries.

The court heard Leila should have had a CT scan to test for a perforated bowel.

Dr McMellon told the court Leila appeared to be clinically improving and "was reporting that she had no more pain" after she was given two doses of pain medication and discharged.

But Leila continued to vomit and have stomach pains and her parents took her to a GP the next morning.

That doctor did not examine her abdomen or check her vital signs, the inquest has been told.

Leila's condition worsened that afternoon and into the next morning.

When she became unresponsive her parents rushed her to the hospital, which was a short drive from their house. But the emergency department was locked up and unattended.

“(There were) no doctors there… I called triple-0 while we were there (and) two nurses came out (and started CPR),” Ricky Harkin, Leila’s father, said last year.

While hospital staff were able to restart Leila’s heart, she was pronounced dead around 8am that day.

Dr McMellon told Deputy State Coroner Anthony Schapel that Leila didn't have the fatal bowel perforation when she attended her.

"I know that she did not have it from my examination," Dr McMellon said.

She also said Leila’s family were told to go seek further medical help if Leila’s condition worsened, which Leila's mother disputes.

"I feel like they [the health system] failed her,” Mrs Harkin told the Sunday Mail in October last year.

"The people that were working were under pressure, overworked — there is such a strain on the health system. I feel like my daughter was a victim of that."

The inquest continues.