A 16-year-old died from a cardiac arrest caused by chronic constipation, an inquest has heard.
Emily Titterington's GP said her death could have been prevented if she had been treated differently.
The inquest at Truro City Hall, Cornwall, was told Miss Titterington had refused to be examined in the days leading up to her death.
A Home Office pathologist said the case was "like nothing she'd ever seen before".
Miss Titterington collapsed and died at her home in St Austell in February 2013.
Giving evidence, her older sister Hannah Herbert said their mother had told her that her younger sister had not gone to the toilet for six to eight weeks and that this was routine.
Mrs Herbert also revealed she had contacted social services telling them "something terrible might happen" if Emily stayed in the same environment.
Miss Titterington's GP, Dr James, said he found no evidence of safeguarding issues, and that her mother, Geraldine Titterington, had tried to persuade her to be examined.
He told the coroner he had prescribed laxatives, but that with hindsight had he examined her abdomen, "we would be having a different conversation".
"Her death could have been prevented with the right treatment at the right point," he said.