WINNIPEG, Manitoba (Reuters) - It took an airport metal detector to give a Canadian woman a clue to why she was suffering from persistent stomach aches four months after having abdominal surgery. Despite the detector's beep, airport security guards in Regina, Saskatchewan, were unable to find any metal on her body before the woman's October flight to Calgary, Alberta. Several days later the woman had an X-ray. It showed a 12-inch-long, 2-inch-wide surgical retractor, used to hold incisions open, had been left in her abdomen after surgery four months earlier at the Regina General Hospital. The woman now wants compensation...