University Hospital's fertility clinic says it had been experiencing problems with a storage tank for several weeks before it malfunctioned last month and ruined more than 4,000 eggs and embryos. It's twice the number originally reported by the hospital.
University Hospitals says the problem forced the clinic's staff to manually fill liquid nitrogen into the tank to keep the embryos frozen.
UH also says an alarm system was turned off on a storage tank that should have alerted staff to changes in the temperature on March 4.
UH CEO Tom Zenty issued an apology on Tuesday via a video posted on Facebook.