Massachusetts has indefinitely suspended a surgeon's medical license because he left a patient anesthetized on an operating table with an open incision in his back while he went to a bank several blocks away.

The patient was not harmed, but the surgeon, Dr. David C. Arndt, created an immediate threat when he left the patient at Mount Auburn Hospital in Cambridge to go to a bank in Harvard Square, the State Board of Registration in Medicine said on Wednesday.

''I've never seen anything quite like this,'' said Nancy Achin Sullivan, executive director of the board.

An investigator for the board who interviewed the operating room staff and other hospital employees said the incident took place on July 10.