A toddler ended up in hospital when the thermometer his mum had inserted into his bottom disappeared from view when he fell over and sat on it.
The 18-month-old's mother said he "wouldn't sit still" and "kept moving" as she tried to check his temperature, concerned he had a fever.
The boy from Wenzhou City in East China's Zhejiang Province then wriggled away from his mum, falling onto the floor with the instrument still inserted.
He sat on the thermometer which then became lodged in his rectum and his mum unable to retrieve it.
Doctor Shao Fangbin with the Yuying Children's Hospital, took scans which clearly highlighted the thermometer, lodged in the child's rectal passage.
He said: "The mother came over after a few hours. She was in quite a lot of panic at the time."
Given the boy's young age, Shao decided against an endoscopy and instead waited to see whether the thermometer would be expelled naturally.
However, after two days the instrument had only moved further in to the boy's intestines, leaving the medic no choice but to operate.
Shao said: "The thermometer was lying to the right of his abdomen, so we went in with an endoscope, put it in a bag, and pulled it out of the incision."
The doctor noted it was fortunate that mercury did not spill out of the thermometer.
The boy has since been discharged and is not expected to suffer any long-term effects from the injury.