A surgeon sometimes moves from one surgery to the next before the first one is completed, leaving junior surgeons, residents and physician assistants to complete the noncritical portions of the procedure. The practice happens tens of thousands of times per year, but one might wonder: Are such overlapping operations safe?

For the most part they are, but with two potentially important exceptions, according to research by investigators at Harvard Medical School and Stanford University published Feb. 26 in JAMA and thought to be one of the most comprehensive analyses on the subject to date.

Link to full Harvard Medical School release on study led by MGH physician Anupam Jena.