In vitro fertilization of an egg cell. Embryos that are kept frozen can remain viable almost indefinitely but at room temperature will only survive a few seconds. (iStock)

In what many reproductive health experts have called a stunning coincidence, two fertility centers in different parts of the country experienced malfunctions in their freezing tanks on the same weekend in early March. Thousands of eggs and embryos were probably lost. Would-be parents are suing.

Here's what we know about what happened at the University Hospitals Ahuja Medical Center's Fertility Center in Cleveland and the Pacific Fertility Center in San Francisco, how the country's regulatory process works with reproductive health services and how investigations could unfold.

Let's start at the beginning. How are frozen eggs and embryos typically stored?

Eggs and embryos are kept in tanks of supercooled liquid nitrogen that look something like the propane canisters you might use for your barbecue grill. Inside the tanks is a combination of towers and canisters that can hold from roughly 5,000 to 30,000 “straws” of material. They are usually in secure-access rooms with sensors and alarms that are monitored 24/7. If nitrogen levels get too low or temperatures begin to rise, an emergency signal goes out to fertility clinic personnel.

Some tanks are hooked to hoses that fill them automatically with liquid nitrogen, while others must be filled manually every few days or weekly. Most clinics have battery backups that can power the tanks for 24 to 72 hours in case of an electrical failure or during a move.

So what went wrong?

In Ohio, staff arrived on the morning of March 4 as an alarm in the storage area signaled an “unexpected temperature fluctuation” in one tank holding about 2,000 egg and embryo specimens. According to the Cleveland Plain-Dealer, “the storage tank had off-site monitoring and an audible alarm that would alert staff to such a temperature change.” WKYC reported that the temperature had increased in the top of the tank but was still cold at the bottom of the tank.

In California the same weekend, officials at Pacific Fertility found a similar problem with their storage tank No. 4. According to the first story in The Washington Post:

It “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.”

The clinic's president said the tank's nitrogen levels were immediately replenished and shortly thereafter the specimens were moved to a new tank. The clinic said “several thousand” eggs and embryos were affected but declined to provide more specific numbers.

It's unclear at this point what led to the malfunctions. Both human error and mechanical failure are possibilities.

The University Hospitals Ahuja Medical Center in Ohio and Pacific Fertility Center in California each experienced equipment failures on March 4 that may have damaged hundreds of frozen eggs and embryos. (Tony Dejak/AP)

Are the eggs and embryos completely destroyed?

The University Hospitals facility has said it doesn't know yet whether any of the eggs and embryos remain viable. Pacific Fertility said that it would thaw eggs or embryos for patients seeking to get pregnant to see if they can still be used. Embryologists can tell if they survived by looking at the cells through a microscope.

Embryos can only survive for seconds at room temperature but can be viable for decades when kept frozen at around minus-196 degrees Celsius, the temperature of liquid nitrogen.

It's possible that different samples heated to different temperatures inside the tanks depending on where they were located — so some may be fine while others are not.

I have my eggs/embryos in storage, and I'm freaking out. How often does this type of thing happen? How do I know if my facility has the right safety and security?

No one keeps comprehensive statistics on how often eggs or embryos are accidentally destroyed. The College of American Pathologists (CAP) receives reports of problems from the 350 reproductive labs it accredits. Officials said on Monday that such incidents are “extremely rare” but declined to release more specific data. Keep in mind that accreditation is voluntary in most states so the organization's information would be incomplete.

If you are concerned about your facility's storage and monitoring procedures, ask questions. In the wake of the problems in Ohio and California, many fertility clinics are reevaluating their own practices. Ask whether yours has certification from CAP or another oversight group, but be aware that even accredited facilities may have problems. The Ohio and California clinics with the recent malfunctions were CAP-accredited.

If you are uncomfortable with the answers you are getting, you may be tempted to move your eggs or embryos from one facility to another. This isn't necessarily a good idea. The transportation process itself can be risky, with a chance of the material being damaged en route.

How are fertility clinics regulated? Shouldn't some federal agency be monitoring these types of incidents?

The short answer is that the Centers for Medicare and Medicaid Services and the Food and Drug Administration oversee only certain aspects of fertility labs. The Centers for Disease Control and Prevention collects and publishes data about in vitro fertilization. None is charged with inspecting clinics’ storage tanks or tracking reports of eggs or embryos being damaged.

This explanation comes with a lot of asterisks and footnotes, however.

The first thing to know is that most U.S. laboratories that work with blood, tissue and other samples from humans are regulated under the Clinical Laboratory Improvement Amendments (CLIA) of 1988. CMS, FDA and CDC have joint responsibility for the law, which empowers the government to monitor performance, conduct inspections and enforce compliance.

Some parts of what fertility labs do — such as andrology (which includes semen analysis) and endocrinology (testing hormone levels) — fall under CLIA. Embryology — which involves the retrieval of eggs, their fertilization and the transfer and storage of gametes — does not.

The issue is further complicated by the fact that cryotanks are at the center of both incidents, and those tanks are considered medical devices, which the FDA does regulate.

State policies vary. California and a number of states explicitly require fertility labs to be accredited and inspected. Others, including Ohio, do not.

CAP is the nation's top accreditation organization for laboratories and has been doing this sort of thing for more than 70 years. It is responsible for inspecting and monitoring 8,000 labs, including reproductive ones. Denise Driscoll, CAP's senior director of accreditation and regulatory affairs, describes a rigorous biannual inspection process that involves about 560 different checklist items, including backup systems for cryo-preservation tanks and 24-hour monitoring of alarm systems.

During their most recent inspections, both the Cleveland fertility center — on Apr. 26, 2016 — and the San Francisco fertility center — on Jan. 23, 2017 — met those criteria.

Who is investigating? And what could happen if the clinics are found to be at fault? 

CAP, which has opened a formal investigation into the incidents, said it could pull accreditation if a lab is found to be at fault. Such action could hurt a clinic's reputation with consumers and affect its bottom line.

In California, losing CAP accreditation could also lead to a clinic no longer being able to operate. A spokesman for the California Department of Public Health confirmed it is investigating the incident there but declined to comment further.

CAP officials said that they are constantly reassessing their standards and that the incidents may prompt them to issue new guidelines.

A number of other government entities and industry or professional groups are also acting.

The FDA said in an emailed statement to The Washington Post that it “is communicating with local health authorities to learn more about these storage tank failures.”

The Ohio Department of Health, in response to questions from The Post, said while it “does not have regulatory authority over fertility clinics under Ohio law,” state licensing boards do oversee the physicians, nurses and other health-care professionals at the facilities.

The American Society for Reproductive Medicine, which represents physicians and other workers in the field, said it will review both incidents and make recommendations to its members.

The clinics' most serious challenges may be patient lawsuits. There are at least two separate lawsuits in Ohio and a class-action filing in California, and more are likely in coming weeks.

The first was filed Sunday on behalf of Amber and Elliot Ash, who live just outside Cleveland. Elliot had stored sperm in his early 20s before treatment for cancer. When the news broke this week, his wife said, “My heart just sank. I spent the day very, very sick.”

Read more:

Patients mobilize to take legal action against fertility clinics with malfunctions