[caption id="attachment_24660" align="alignleft"]gallbladder removal, surgery in the operation theatre[/caption]ROCHESTER, Minn. — Why are major surgical errors called “never events?” Because they shouldn’t happen — but do. Mayo Clinic researchers identified 69 never events among 1.5 million invasive procedures performed over five years and detailed why each occurred. Using a system created to investigate military plane crashes, they coded the human behaviors involved to identify any environmental, organizational, job and individual characteristics that led to the never events. Their discovery: 628 human factors contributed to the errors overall, roughly four to nine per event. The study results are published in the journal Surgery.