A government report released this week on a cancer-spreading surgical device highlights a weakness in the Food and Drug Administration’s ability to spot harms from drugs and devices on the market.

The surgical device, called a power morcellator, has been on the market since 1991 and is FDA-approved for use in minimally invasive gynecological surgeries, including removing benign uterine tumors (fibroids). The device shreds tissue into small pieces so it can be removed from the body through small incisions. But in the event that a patient has an undiagnosed cancer, the device can fling cancer cells throughout the body, where they can seed new tumors. The first time the FDA got a report of this happening was in 2013—and it was from a patient, not a doctor or hospital using the device. By that time, at least 50,000 US women were having surgery with the device a year, The New York Times reports.

The patient, Dr. Amy Reed, then 40, underwent a hysterectomy due to fibroids, unaware that she had a hidden, aggressive type of cancer. The surgery spread the tumor cells, which became advanced Stage 4 cancer. According to the Times, she has been fighting it ever since, undergoing surgeries for cancer in her abdomen, spine, and lungs, as well as undergoing chemotherapy, radiation, and other treatments.

Following media coverage of her case, more reports came in, totaling 285 by September 2016.

Of those 285 cases, only five occurred after the FDA put out a warning about the device in 2014, which it did in response to Reed’s case, the first time it was aware of the problem. While this suggests the FDA’s actions were effective at reducing harms to patients, it raises questions as to why it took so long for the FDA to get involved.

Currently, the FDA’s “adverse event” reporting system is passive—it relies solely on manufacturers, doctors, hospitals, patients, and other care providers to report problems.

The new report this week, conducted by the Government Accountability Office, found that the FDA didn’t do anything wrong in how it handled the situation based on current regulations. But the report says:

FDA officials noted, however, the limitations in the current, passive, medical device reporting system, which relies on people to identify that a harm occurred or a risk is present, recognize that the harm or risk is associated with the use of a particular device, and take the time to report it.

“The passive reporting of adverse events is a weak system,” Marcia Crosse, the director for health care at the accountability office, said in an interview with the Times.

In a statement, the FDA said it was working on establishing better systems to evaluate device and drug performance in clinical practice.

Editor's Note: The article was updated to clarify the 2013 report.