Troy Almond was 17 months old when he died on March 22, 2016, less than 24 hours after being discharged from the Shoalhaven District Hospital emergency department.

An autopsy revealed the Nowra boy had died of sepsis.

Deputy state coroner Teresa O’Sullivan on Monday found Troy died due to the failure of the hospital's treating specialist to recognise the signs of toxicity caused by possible sepsis, to investigate the possibility of sepsis, and to administer antibiotics.

She accepted expert opinions the bacterial infection was treatable with early detection and early administration of antibiotic therapy to which the microorganism was sensitive.

Troy’s parents Kim Macklin and Daniel Almond sat in the Nowra Courthouse holding hands, a portrait of their late son on their knees.

Mr Almond said that when Troy died, it was "like the sun had gone out".

“All we can hope is by us going through this, it can contribute to this not happening again," Mr Almond said.

“Through Troy’s loss and our loss hopefully other families won’t have to experience the same circumstances."

Ms Macklin said they missed their son “tremendously”, describing him as a “very bright, beautiful, happy, outgoing little boy”.

“He was super tight-knit with his brothers and they were fiercely protective of him," she said. “It is a terrible loss for all of us.”

The inquest heard the toddler had a temperature and was lethargic and vomiting when his mother took him into the hospital's emergency department just after 10am on March 21, 2016.

After spending four hours in the emergency department where he received treatment, he was discharged suffering from what was described as a viral infection.

The inquest heard a number of NSW Health Between the Flag procedures for sepsis pathway in pediatric patients which raises a “red flag” for a number of health issues, such as heart rate, oxygen levels and temperature which fall outside desired levels, were not used.

Troy had red and yellow flags for high temperatures and increased heart rates.

The toddler’s condition deteriorated overnight and he woke the following day with diarrhoea and had begun vomiting again and became "unresponsive" later that morning, prompting his parents to phone triple-0.

They performed CPR until paramedics arrived and transported him to hospital, where he was pronounced dead at 12.50pm.

Emergency department doctor Babak Tajvidi apologised to Troy’s parents, saying he had “made a mistake”. During his evidence last month Dr Tajvidi conceded the toddler “most likely” already had sepsis when he first presented to hospital.

Ms O’Sullivan said procedural changes had already taken place at the hospital, including ongoing training, but encouraged the hospital to “continue to review and update their staff orientation and training".

The coroner expressed her gratitude to Troy’s parents, who attended every day of the inquest.

“Their dignity and patience throughout the coronial process was admirable," Ms O'Sullivan said.

"I know that there are no words to comfort them. The best that I can do is to acknowledge the enormity of their loss and their love for their beautiful son, Troy.” she said.

Shoalhaven District Hospital acting director of nursing Brad Scotcher said procedures at the hospital had changed following Troy's death.

“We really regret what’s happened,” Mr Scotcher said outside of court.

“We’ve put significant protocols in place to make sure our staff are well trained in the use of systems required to look after children who present to us with sepsis and that we work harder on identifying and managing that early."

Mr Scotcher would not comment on what had happened to the staff involved in the incident.