The 47-year-old was still on the treatment table when she realised at some point that the acupuncturist had left and shut the office in the US state of Washington.

The woman said she tried to leave - but the doors were closed and needed a key to unlock them, even from the inside.

Police spokesman Mark Young said she set off motion detector alarms while attempting to get out and finally called 911 for help at about 7:30pm.

Officers responded and were able to get her out of the building and the woman was unharmed, according to the Bellingham Herald.

She said she had been undergoing treatment at Discovering Health in Bellingham, Washington.

A call to the clinic was returned by a lawyer, who declined to comment.

A Department of Health spokeswoman said if the patient filed a complaint, it would be investigated.

She would not speculate on what the penalty, if any, would be.