In a letter sent to 950 patients, University Hospitals Fertility Center blames human error for the loss of 4,000 eggs and embryos, twice the number initially reported.

The letter says the hospital is “heartbroken” to inform patients it is “unlikely” any of the eggs and embryos are viable.

The letter says a remote alarm system on the storage tank containing the eggs and embryos, which was designed to alert a UH employee to temperature fluctuations, was turned off.

It is unclear when the remote alarm was turned off, but an alert to an employee as the temperature inside the tank began to rise Saturday night was not sent or received, according to the letter.

It is also unclear who turned off the alarm and how long the alarm was turned off.

The lab was not staffed March 3, the night of the malfunction.

There was also a history of malfunctions involving the storage tank.

In the letter, UH said the storage tank in question “needed preventative maintenance.”

For weeks prior to the malfunction on March 3, “we experienced difficulty with what is called the liquid nitrogen automatic fill” and were working with the manufacturer to correct the problem.

“My clients’ lives and future aspirations were crushed and destroyed. Finding out how simple of a matter it would have been to prevent this tragedy shakes my faith in the medical profession to the core,” said Brian Taubman, an attorney representing patients affected by the malfunction, in a statement to 5 On Your Side Investigators.

“My clients trusted UH with their future family, never doubting that those lives were safeguarded and with the flip of a switch their lives and potential lives were changed forever,” said Taubman.

The hospital also says it takes responsibility for the failures and apologized several times to the affected patients. The letter says, “Those failures should not have happened, we take responsibility for them – and we are so sorry that our failures caused such a devastating loss for you.”