An employee arranges a test tube in a container used to freeze human eggs for in vitro fertilization at a fertility clinic in Greece. (Kostas Tsironis/Bloomberg)

A long-established San Francisco fertility clinic had a liquid nitrogen failure in a storage tank in which thousands of eggs and embryos are kept frozen for future use, jeopardizing the tissue that hundreds of women have deposited there in hope of having children.

The March 4 incident at Pacific Fertility Clinic, acknowledged on Sunday by the facility’s president, is the second such admission in a matter of days, coming on the heels of a similar malfunction the same weekend at an unrelated clinic in Cleveland.

The pair of incidents, with powerful emotional and financial consequences, come as the number of U.S. women freezing their eggs has soared in recent years as assisted reproductive technology has advanced and become increasingly popular. Women freeze eggs in order to postpone pregnancy until a later date or to have a supply for in vitro fertilization attempts.

As at the Univerisity Hospitals Fertility Center in Cleveland in recent days, the half-dozen doctors at the Pacific Fertility Clinic raced over the weekend to notify their patients, according to Carl Herbert, a physician and the clinic’s president.

Herbert said in an interview that he and colleagues began making phone calls on Saturday night to some 400 patients who had all their eggs or embryos stored in the clinic’s storage tank #4. Early Sunday, the clinic also sent out emails explaining what had happened to two other groups: Roughly 100 who had tissue in both the problematic tank and another tank. And a larger group whose tissue was unaffected.

“There is just not an ability to do this unemotionally. Anger is a big part of the phone call,” Herbert said of his discussions with patients. “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.”

According to Herbert, the extent to which the chemical failure damaged the eggs and embryos remains unclear. He said that the clinic’s staff thawed a few eggs and found that they remain viable, though they do not know how many are still usable. They have not checked any of the embryos, he said.

Herbert said that the problem was discovered by the clinic’s laboratory director, who noticed during a routine check of the steel storage tanks that the level of liquid nitrogen in one tank was too low. Too little liquid nitrogen causes the temperature to rise, with a risk of damage to the tissue housed in vials called cryolocks. One to three eggs may be stored in a unit. Embryos — fertilized eggs - are stored individually.

The clinic declined to specify the number of eggs and embryos affected but said that “several thousand” were in the waist-high tank. They amounted to an estimated 10 to 15 percent of the total stored at the facility, according to Pacific Fertility Clinic spokesperson Alden Romney.

According to Herbert, once the failure was discovered, the lab director immediately had a spare storage tank brought into the lab and filled with liquid nitrogen, so that the eggs and embryos could be transferred. “This was a terrible incident,” Herbert said, “but I was reassured that . . .he did everything anybody could ever want to do.”

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

The eggs and embryos in tank #4 had been in storage for as long as 10 years, though the tank still was in active use, Herbert said. While the staff spent days sorting through records to verify which patients’ tissue was inside, he said they do not yet know how many of them were still planning to use it.

According to the clinic’s website, its fees for egg freezing are $8,345 for the initial cycle and $6,995 for each subsequent round. Herbert said, for patients still eager to use their eggs or embryos to try to become pregnant, the physicians and other staff will first thaw them to find out whether they are viable. If they are not, he said, “we are going to make our patients happy one way or another.”

Herbert is a longtime physician and researcher in assisted reproductive technology. In 1982, he helped to develop one of the nation’s earliest reproductive technology programs at Vanderbilt University Medical Center. He moved to San Francisco in 1990 and, with colleagues, purchased Pacific Fertility Center nine years later.

In the Cleveland incident at University Hospitals Ahuja Medical Center’s fertility clinic, officials notified about 700 patients that their frozen eggs and embryos may have been damaged. Some dated to the 1980s.

Hospital officials said in a statement on Thursday that they were investigating the incident and that it remained unknown whether the cause there was a human error or mechanical failure.

Read more

The struggle to conceive with frozen eggs.

Five things you need to know if you are considering freezing your eggs.

Discounts, guarantees and the search for ‘good’ genes: How the booming fertility business is changing the American family.