Urgent action needs to be taken by the NHS after call handlers missed opportunities to save the life of a six-year-old boy, a coroner has warned.
Sebastian Hibberd died of intussusception at Derriford Hospital in Plymouth on 12 October 2015.
In a report, coroner Ian Arrow told NHS England and NHS Digital more children could die unless changes are made to how 111 calls are handled.
NHS Digital said it would "ensure any necessary lessons are learned".
Intussusception is a condition in which the bowel "telescopes" in on itself, causing the walls to press on one another and creating a blockage.
Sebastian's family made repeated calls to the NHS 111 number reporting he was delirious, had cold hands and feet and had been throwing up green vomit.
Call handlers failed to spot warning signs part of the boy's bowel had collapsed and an inquest in February concluded there were "several missed opportunities" to save him.
Mr Arrow's Prevention of Future Deaths Report, seen by the BBC, recommended NHS England and NHS Digital carry out a review of their procedures.
It warned that call handlers were not being "adequately assisted" by the algorithm used to assess patients over the phone.
"In my opinion there is a risk that future deaths will occur unless action is taken," he wrote.
"Without changes in the NHS Pathways the 111 call handlers will not be adequately assisted by the Pathways to recognise the acutely unwell child."
NHS Pathways is a clinical tool used for assessing, triaging and directing the public to urgent and emergency care services.
Mr Arrow said there were inadequate questions for children over five about some of the symptoms for intussusception and it did not allow for a meaningful pain assessment.
He called for more support for call handlers dealing with unusual cases and asked that NHS England reviews the need for a fail-safe mechanism to ensure a face-to-face meeting with a doctor is arranged following repeated calls over the condition of a child.
Sebastian's parents Russell and Nataliya said they hoped the coroner's report would "prevent any other family having to live through the nightmare that we have".
NHS Digital said it would "consider the evidence presented and the findings by the coroner, to ensure that any necessary lessons are learned".
NHS England has not yet commented.