In 1954, the human kidney became the first organ to be transplanted successfully, an achievement that later earned surgeon Joseph Murray, MD, a Nobel Prize. Today, kidneys are the most commonly transplanted organ in the United States. Doctors at the NYU Langone Transplant Institute performed more than 300 kidney transplants last year alone. And the number of those patients who survived one year with their new kidney exceeded the national average. Despite the prevalence and success of the procedure, many people are in the dark about how it works. Here are four little-known facts about kidney transplants.

You Don’t Need to Be on Dialysis to Qualify for a Kidney Transplant

In fact, patients who receive an early transplant enjoy better long-term health and a higher quality of life. For one, it eliminates the need for dialysis, a procedure that uses a machine to do the work of the kidneys. “For patients with end-stage kidney disease, the outcomes of a kidney transplant are superior to being on long-term dialysis,” explains Robert Montgomery, MD, DPhil, director of the Transplant Institute and chair of the Department of Surgery. “A transplant more than doubles the lifespan of the patient.” At NYU Langone, 28 percent of kidney recipients receive a transplant before they need dialysis.

One New Kidney Is All That’s Needed

Although we’re born with two kidneys, most transplant recipients require only one. “A single, healthy kidney will usually do enough work,” says transplant surgeon Bruce E. Gelb, MD. “That means that one deceased donor can save the lives of two people.” When only one kidney is present, its filtering units, or nephrons, compensate by increasing in size to handle the extra load of waste products and excess fluid they must filter from the blood. One caveat here is age. If a deceased donor is very young or very old, a recipient may receive both kidneys to provide enough functional nephrons. Though the majority of kidneys transplanted come from deceased organ donors, getting a transplant from a living donor is ideal. The kidneys almost always last longer, patients experience fewer complications, and there’s no need for the patient to spend time on the national waiting list. Living donors usually spend two days in the hospital and can resume normal activities in three to four weeks.

Kidneys That Stop Working Stay Put

Surgeons typically don’t remove the recipient’s native kidneys—unless they’re greatly enlarged or causing severe problems, such as high blood pressure or infection. “The nonfunctioning kidneys just get smaller over time,” notes Dr. Gelb.

A New Kidney Isn’t Placed in the Same Spot as the Original One

Unlike a transplanted heart, lung, or liver, which occupies the same space as the original organ, a new kidney is implanted in the lower abdomen, where it can more easily be connected to the bladder and major blood vessels. “Our native kidneys sit high in the abdomen, partially protected by the ribs, so accessing them requires a more invasive surgery and risks creating scar tissue in the abdomen,” explains Dr. Gelb. “Though the kidney is about the size of a fist, there’s a lot of flexibility in the abdomen. The transplanted kidney can be placed there without compromising nearby organs and is readily accessible if a biopsy is needed.”