Over the weekend, the Pacific Fertility Clinic in San Francisco began notifying some 400 patients that the eggs they’d frozen for future use could have been damaged due to a liquid nitrogen failure in a storage tank on March 4.

The clinic also sent emails to two other groups who stored their eggs at the facility: Roughly 100 patients whose tissue was split between tank No. 4 — the one that malfunctioned — and other tanks, and a larger group whose tissue was unaffected.

“Anger is a big part of the phone call,” said Carl Herbert, the clinic’s president “Our goal is to provide all the patients we see with some kind of a family. . . . We need to think: If this tissue doesn’t work, what are the next steps, and have you not feel defeated.”

Thousands of eggs and embryos were kept in tank No. 4, and they had been in storage for as long as 10 years. The extent to which the chemical failure damaged the eggs and embryos remains unclear, the clinic said, but some may no longer be usable.

The malfunction in tank No. 4

Officials at Pacific Fertility said the latest problem was discovered by the clinic’s laboratory director, who noticed during a routine check that the level of liquid nitrogen in one of the clinic’s steel storage tanks had fallen too low. Too little liquid nitrogen causes the temperature in the waist-high tanks to rise, risking damage to tissue housed in vials called cryolocks. Each vial can contain as many as three eggs; embryos — fertilized eggs — are stored individually.

Herbert said the lab director immediately transferred the threatened eggs and embryos to a spare storage tank filled with liquid nitrogen. Staff then spent days sorting through records to verify which patients had tissue inside.

When clinic staff thawed a few eggs affected by the malfunction, they found that the tissue remained viable. Staff have not checked any of the embryos, he said.

“This was a terrible incident,” Herbert said, “but I was reassured that . . . [staff] did everything anybody could ever want to do.”

The clinic has reported the incident to the College of American Pathologists, which certifies labs, and the overseers of California’s tissue banks, Herbert said. The clinic also has brought in a multidisciplinary team to investigate the malfunctioning tank and, he said, “every aspect that involves cryopreservation.”

Another incident puts eggs at risk in Ohio

Another malfunction occurred in Cleveland last week. Officials at the University Hospitals Ahuja Medical Center’s fertility clinic notified about 700 patients that their frozen eggs and embryos may have been damaged. Some dated to the 1980s.

The two episodes carry powerful emotional and financial consequences.

According to its website, Pacific Fertility’s fees for egg-freezing start at $8,345 for an initial cycle and $6,995 for subsequent rounds. In each cycle, a patient’s ovaries are stimulated with drugs to produce multiple eggs, which are then harvested by doctors and frozen.

Although individual women have reported having frozen eggs damaged in storage or in transit, a spokesman for the American Society for Reproductive Medicine, a major professional organization, said such large-scale incidents appear to be unprecedented.

“We can’t say definitively nothing like this has ever happened, but we are certainly not aware of anything,” said Sean Tipton, the association’s chief policy, advocacy and development officer. “Now that we have a second incident, it becomes very important that we learn as much as we can about both, to search for commonalities and see if there are . . . risks that have now come to light that need to be addressed.”

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