About 4,000 frozen eggs and embryos were lost when a tank failed at the University Hospital Fertility Center in Cleveland, the clinic said more than three weeks after the initial incident. That number is more than double what was previously estimated by the facility. In letters sent out to affected patients, the hospital said it was unlikely that any of the eggs and embryos are viable and blamed the loss on human error. The hospital explained that an alarm system that alerts staffers to temperature swings had been shut off, but they don't know who turned it off. Meanwhile, NBC News found that the maker of the tanks used in the hospital has a “a history of previous malfunctions dating back almost 15 years.” Regulators in the U.K. observed 21 incidents of Custom Biogenic Systems equipment failing in 2003, noting that the manufacturer was aware of the incidents, as well.