Hospital staff failed to carry out the last check before a teenager killed herself, a court heard.
Kelly Campbell, 17, from Basildon, had a history of self-harm and suicidal thoughts.
She was being treated for bulimia on the Poplar adolescent ward at Rochford Hospital, run by Essex Partnership University Trust, at the time.
Although initially a voluntary patient, she was eventually detained under the Mental Health Act as professionals feared for her safety after a similar suicide attempt on the ward in December last year.
Having initially been under constant supervision, at the time of death this had been relaxed to hourly observations - the last of which was carried out at midnight.
She was found hanged in the bathroom at 2am that night. An inquest into her death is underway at Essex Coroners’ Court.
Det Insp Ashley Howard, of Essex Police, told the court the death was not being treated as suspicious. He also noted the 1am check was not conducted by staff.
Child and adolescent psychiatrist Dr Joshua Westbury told the court he could not determine whether the check would have prevented Kelly’s death.
When speaking about her death, he said: “I did not feel that was likely to happen.
“I was very concerned she might self-harm or overdose. The incident in December seemed exceptional.”
Dr Westbury described Kelly as "an unusually challenging" patient who was "ambivalent" about her recovery.
He said: "In some ways she wanted to get better and in some ways she didn't."
He told the court he felt "stuck" when it came to treating her and said he had resorted to several different approaches to her treatment.
When asked by Essex senior coroner Caroline Beasley Murray if he would have treated Kelly any differently in hindsight, he said: “I don’t think I can answer that question.”
She was found hanged in her room in the early hours of February 9 this year.
The inquest in front of a jury continues.
Anyone who is having suicidal thoughts can talk to the Samaritans by ringing 116 123 any time of the day or night.
The number is free and trained volunteers are there to listen to what you have to say.
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