It was an unnerving piece of news: a person looking to save a life donated a kidney, and died after the surgery while the recipient lived. And it highlights a risk everyone faces in even routine surgeries.

The University of California San Francisco voluntarily shut down its living donor program after the October accident, a scenario that has been called a “nightmare” by Dr. Steven Katznelson, who is the medical director of California Pacific Medical Center’s kidney transplantation program in San Francisco, according to an SFGate.com report. Authorities are investigating the death to determine why it happened and what can be done to prevent in the future.

The reality is that there are no safe surgeries, and the main culprit is anesthesia, or the practice of temporarily inducing a state of unconsciousness.

Fortunately, the risk is small for kidney donors, who face a 0.03 percent chance of dying.

But anesthesia is always a risk in any type of surgery, and underscores why the medical community must be so careful in employing it.

Deaths from anesthesia have plummeted since the 1940s, declining from 640 per one million patients to just four per one million by the end of the 1980s.

But according to a TIME report, death rates may be back on the rise to about seven patients for every million, and within a year one in 20 died from general anesthesia — one in 10 for those over 65. Of course, much of this rise may be due to the fact that more and more older adults are being operated on.

The reality is that people who have complications like heart problems and high blood pressure face a higher risk when it comes to anesthesia, and this is one of the factors that must be weighed when discussing whether a surgery is necessary with a doctor.

Being obese also has an impact. It’s tough to tell how much an overweight person needs to go under, and that can potentially lead to giving someone the wrong amount.

Anesthetists monitor and regulate breathing and circulation during the surgery to make sure nothing goes wrong.