When an alarm system for a storage tank in a fertility clinic was found to have been erring for a period of weeks, it led to the destruction of over 4,000 frozen eggs and embryos — double than what the clinic initially thought.

The University Hospitals Fertility Center in Cleveland, Ohio, isn't certain about who turned off the alarm or exactly what happened, it wrote in a letter sent to affected patients. Had it not malfunctioned, the alarm would have alerted employees of rising temperatures in the tank.

"We are still seeking those answers," reads the letter.

Fertility Clinic Fiasco

The incident, along with another one that happened on the same day but in San Francisco, are two of the biggest cases of embryo losses in history, prompting fertility clinics and centers around the country to get a more thorough look at their procedures.

Several couples who trusted the Cleveland clinic to have their embryos stored say they're devastated about the incident because that means they might not be able to have children going forward. Attorney Mark DiCello, representing some of the affected patients, thinks some person inside the clinic deliberately turned the alarm system off because "they were having problems and they made the decision they weren't going to deal with it."

About 950 patients are affected, and it's dubious to believe that any of the destroyed 4,000 eggs and embryos remain viable for fertilization. University Hospitals apologized to its patients and blames human error for the incident.

Malfunctioning Systems

At the same time, NBC News has learned about recurring problems in other tanks that came from the same manufacturer. An investigation showed that Custom Biogenic Systems has a history of problems dating back to nearly 15 years. One such incident in the UK saw a cancer patient having his sperm frozen for fear of passing away before conceiving of another child.

The freezer storing his sperm malfunctioned, and the sperm was suddenly useless. The patient eventually died. The clinic simply said there had been a technical malfunction with the freezer unit storing the sperm, and that was that.

In 2003, it was reported that Custom Biogenic Systems was aware of 21 incidents where its freezers malfunctioned. That was just in the UK. Soon after, the manufacturer upgraded 95 percent of the devices and vowed for the remaining 5 percent to be complete by 2006. Therefore, malfunction issues shouldn't be persisting now.

The University Hospitals clinic says it's now upgraded to a new storage tank and a new alarm system. Furthermore, it has also changed the monitoring system of the tanks.