A toddler has died after doctors failed to spot she was ill with meningitis, her parents have said.
Lili Backhouse, aged 23 months and one of twins, was taken to Queen's Hospital in Romford, Essex, by her parents Brian and Julie earlier this month.
They claim a doctor said their daughter's illness, which included fever and sickness, was a viral infection and sent her home.
But within a few hours the youngster's health had deteriorated and her parents took her to A&E.
Doctors there diagnosed her with meningitis, but it was too late to save her life.
Lili's twin Lukas fell ill with meningitis just hours after his sister died, but doctors caught the disease and he has made a full recovery.
It is also claimed that another toddler from Essex was sent home after being seen at Queen's on the same day, despite the fact he too had meningitis.
A Just Giving fundraising webpage has been set up in Lili's honour to raise cash for the charity Meningitis UK.
It says: "This donation page has been set up in the memory of Lili Jane Backhouse, who was taken suddenly from us on the 9th January 2011, aged just 23 months.
"It took less than nine hours for this terrible illness to take hold of Lili, and something that the doctors originally dismissed as a cold or virus sadly ended up taking her life just hours later.
"Lili's twin brother, Lukas, also contracted the illness later that day, but due to the tragic circumstances that surrounded Lili, he was treated early enough to fight against it, and luckily won the battle. Lukas was finally discharged from hospital a week later.
"The strain of meningitis that both Lili and Lukas had was meningitis B, the only strain that still has no vaccination."
Interim chief executive for Queen's, Deborah Wheeler, said: "Our thoughts are with the Backhouse family at this extremely difficult time.
"Meningitis is notoriously difficult to diagnose and our doctors did the very best they could for Lili.
"We would be happy to meet with both families to discuss any concerns they have and will be looking into both cases to see if anything could have been done differently."
Steve Dayman, chief executive of Meningitis UK, who lost his son to the disease in 1982, said: "It's always worrying to hear about cases where lives might have been saved.
"Unfortunately we hear stories like this far too frequently.
"It seems that doctors are sending children home too readily, which is often a deadly mistake to make when they're suffering from meningitis as it can kill in under four hours.
"Keeping children in for observation is especially important at this time of the year when cases of both meningitis and flu are rising.
"All medical professionals should know that the sooner antibiotics are administered the better the chances of survival are.
"Parents know their children best and don't go to the doctor's unless they're really concerned.
"Just because a patient doesn't have a headache, stiff neck and dislike of bright light doesn't mean they're not suffering from a life-threatening meningitis infection."