Roughly 1 in 5 kidneys are thrown out each year in the United States. Kidneys are discarded if they are thought not to meet federal guidelines due to scarring or other issues. Many times, these kidneys are donated from older individuals who may have health problems.

But a new study published in the Journal of the American Society of Nephrology indicates that too many kidneys are discarded based only on biopsy results. Researchers say discarded kidneys could be more effective at keeping kidney failure patients alive than dialysis.

"73 percent of deceased donor kidneys with suboptimal biopsy results were still functioning at five years, suggesting that discards based on biopsy findings may be inappropriate and merits further study," said Dr. Sumit Mohan of the Columbia University College of Physicians and Surgeons and New York Presbyterian Hospital, both in New York City. The five-year survival rate on dialysis stands at 35 percent.

Mohan's team studied 975 kidney transplants conducted between 2005 and 2009. In the case of living donors, the researchers found that poor biopsy results did not significantly impact a recipient's health outcomes. In fact, 91 percent of patients lived at least five years with a less-than-optimal kidney.

For deceased donors, 73 percent of kidneys with the poorest results could extend a kidney failure patient's life five years longer than dialysis.

"If I don't get a kidney, my alternative is to stay on dialysis," Mohan said. "Even getting a suboptimal kidney provides a huge survival advantage."

Mohan said living donors are subjected to intense screenings before a transplant occurs to ensure they are healthy enough to donate a kidney. And since these transplants are usually conducted in the same hospital, the organ isn't damaged in transit.

"You should take a living donor kidney regardless of anything else you know about that living donor," Mohan said. "It's always going to be better than a deceased donor kidney."

The United Network for Organ Sharing says nearly 100,000 people are waiting for kidney transplants. The average waiting time to receive a kidney is 3.6 years, and 13 people die every day while waiting for a kidney.

Mohan isn't the only medical professional who says biopsies shouldn't be the sole determiner of usability. Dr. Richard Formica, director of transplant medicine at the Yale School of Medicine, says biopsies are reviewed by pathologists who are not kidney experts. While they can render a general opinion, someone with more training can provide a more nuanced assessment of organ health.

Other factors play into the biopsy results, too. Many samples are frozen, which impacts the results, and the location in the kidney where the sample comes from may not be indicative of the overall health of the entire organ.

"I don't think the way we do biopsies currently in assessing whether or not organs get transplanted gives the clinicians the ability to make an informed decision," Formica said. "That's the problem with biopsy."