It’s tricky to transplant a bladder. How surgeons finally did it

The first successful human bladder transplant could offer hope for people with bladder problems.

On May 4, 2025, Oscar Larrainzar, 41, became the first human to successfully receive a bladder transplant. The surgery was part of a clinical trial developed to demonstrate the feasibility of bladder transplants in patients with terminal bladder diseases. The American Cancer Society estimates there will be about 85,000 new cases of bladder cancer in 2025 in the United States, resulting in about 17,400 deaths, making it the 10th leading cause of cancer death in the country.

The current treatment for bladder dysfunction is to replace or augment a urinary reservoir, usually from a portion of the patient’s intestines, to create a new bladder or a path for urine to leave the body. This procedure comes with risks, including infection, internal bleeding and digestion problems. The bladder also has a complex network of blood vessels, which makes transplantation surgeries technically complicated.

Having lost both kidneys and most of his bladder to cancer, Larrainzar had been on dialysis for seven years to remove waste and excess fluid from his body. In an eight-hour surgery at the Ronald Reagan UCLA Medical Center, a team led by Inderbir Singh Gill of the Keck School of Medicine at the University of Southern California and Nima Nassiri of the University of California, Los Angeles first replaced a kidney, followed by the bladder.

The medical team reported an immediate improvement: The new kidney produced a large amount of urine, which drained correctly into the transplanted bladder. No dialysis was needed following the surgery, and Larrainzar has been stable since.

Gill, a urology professor at USC, spoke to Science News about the successful transplant. This interview has been edited for length and clarity.

SN: What made this surgery possible now?

Gill: Nima Nassiri and I spent four years researching and perfecting the techniques to make this surgery possible using both open and robotic surgical methods. [Given the technical challenges of surgery, including reattaching the blood vessels in the bladder, they had practiced retrievals and transplantations in five recently deceased donors whose cardiac function was maintained on ventilator support.] Much of what made this possible was innovating, refining and perfecting each step of the surgery until we were able to confidently move forward with the clinical trial.

SN: How are you monitoring Oscar Larrainzar’s health now?

Gill: As with any organ transplant, we will be monitoring to ensure that the body does not reject the new organs, and we are cautious of any side effects that the patient may experience. We also will monitor how well the bladder functions — will the patient be able to contract the bladder and urinate properly over the long term, for example.

SN: What’s next for bladder transplants?

Gill: We have seen promising early results with our first patient, and we hope these results are confirmed with future patients who enroll in the clinical trial. We also want to understand the long-term impact of bladder transplantation, including how much function a transplanted bladder can provide and any potential challenges.