The death of a 21-month-old boy despite four calls from his concerned mother to Healthline, the government-funded telephone advice service, does not highlight a need for new practices, the service's medical director says.

Ian St George was addressing the Wellington Coroner's Court yesterday after 23-year-old Aotearoa Tauiliili lost her son Rhys Foaese, who suffered from a rare and undiagnosed congenital abnormality in the diaphragm, the Dominion Post reported.

Rhys died of shock on July 28 last year after his stomach contents spilled out, pathologist Jane Zuccollo told the court.

Ms Tauiliili, who lives in Petone, called Healthline four times the previous night with concerns about her vomiting and restless child.

She was eventually instructed, around 7.40am, to take Rhys to his normal doctor during business hours.

Rhys collapsed at home before the surgery opened. An ambulance was called but he could not be saved.

Dr St George acknowledged Ms Tauiliili could have been told to seek emergency care after the third call, but said if every caller reporting Rhys' symptoms was sent to hospital there would be many unnecessary referrals.

The coroner reserved his decision.