One Year Later: The World's First Bladder Transplant Patient is Thriving

One year ago, Oscar Larrainzar became the first human to receive a fully vascularized bladder transplant.[1][3]

Now, a peer-reviewed study published in The Lancet has chronicled his six-month and one-year outcomes, confirming the experimental procedure's overwhelming success.[2][4]

For decades, bladder transplants were deemed medically impossible. The pelvic cavity contains a highly complex web of microscopic blood vessels, making it exceedingly difficult to establish a reliable blood supply to a donor organ without the tissue dying.[1][6]

Because of this anatomical hurdle, the standard of care for patients with terminal bladder disease has been the construction of a "neobladder." Surgeons would remove a segment of the patient's own intestine and fashion it into a makeshift pouch to hold urine.[5][7]

However, this workaround comes with severe drawbacks. The human intestine is biologically designed to absorb substances, while the bladder is designed to excrete them. This fundamental mismatch frequently leads to chronic bacterial infections, severe metabolic imbalances, and a high risk of long-term kidney damage.[1][5]

Larrainzar, a 43-year-old father of four, knew these complications well. He had survived a rare form of bladder cancer and renal cancer, which necessitated the removal of both his kidneys and the majority of his bladder. For seven years, he was tethered to dialysis machines and relied on external medical equipment just to survive.[3][4]

To offer patients like Larrainzar a better option, Dr. Nima Nassiri of UCLA Health and Dr. Inderbir Gill of USC spent years developing a new approach. They conducted extensive preclinical research, practicing complex robotic retrievals on animal models and cadavers, often working in the middle of the night to perfect the technique.[1][6]

Their breakthrough was treating the bladder as a standalone, fully vascularized organ. Instead of repurposing intestinal tissue, the surgical team prepared to transplant a true donor bladder alongside a donor kidney, preserving the organ's native architecture and blood flow.[2][5]

On May 4, 2025, the team put their protocol to the test in an eight-hour operation. They first transplanted the donor kidney, and then meticulously connected the donor bladder's delicate blood vessels directly to Larrainzar's pelvic blood supply.[3][7]

The results were immediate. As soon as blood flow was restored, the new kidney began producing a large volume of urine, which drained perfectly into the newly vascularized bladder.[1][7]

Because this was a first-in-human trial, the surgical team had to invent the clinical benchmarks for success. According to the data published in The Lancet, the primary 30-day goal was for the new bladder to safely hold 200 milliliters of urine.[2][4]

Larrainzar easily surpassed that metric, reaching a capacity of 270 milliliters by day 30. By the six-month mark, his bladder had stretched to accommodate 600 milliliters—roughly 20 ounces—which is the full capacity of a normal, healthy adult bladder.[4][5]

The recovery process was heavily scrutinized for the study, and the researchers were transparent about the hurdles. On day 25, Larrainzar developed a localized infection caused by a urine leak from a secondary "suprapubic" tube, which had been inserted through his abdomen as a backup drain.[4]

Dr. Nassiri performed a minor follow-up procedure to close the leak and remove the tube. By studying this specific complication, the surgical team determined that future transplants can safely omit these secondary backup tubes entirely, streamlining the postoperative recovery protocol.[1][4]

The human impact of the surgery has been profound. Today, Larrainzar is completely off dialysis, working full-time, and free from catheters. He recently took a family vacation to Las Vegas, where he was able to swim with his 10-year-old daughter for the first time since she was an infant.[3][4]

While Larrainzar's case is a historic triumph, the procedure remains strictly experimental. The operation was part of an ongoing phase-zero clinical trial at UCLA Health designed to rigorously test the feasibility of combined kidney-bladder transplants.[5][6]

The reality of experimental medicine means not every outcome is perfect. The team has since performed a second combined transplant, but the patient experienced a complication that required the new bladder to be removed. Fortunately, the patient's new kidney continues to function well, and the team is planning a rare re-transplant attempt later this year.[1][4]

A third patient, who received the combined transplant more recently, is currently two months post-surgery and is already urinating independently without the need for a catheter, reinforcing the procedure's overall viability.[1]

With two additional surgeries planned for the remainder of 2026, the surgical team is looking toward the future. Dr. Nassiri has stated that the ultimate goal is to expand the protocol to pediatric patients, for whom bladder failure is a leading cause of secondary kidney failure.[1][4]

The successful one-year milestone proves that fully vascularized bladder transplantation is no longer a surgical impossibility. By moving beyond the limitations of intestinal neobladders, medical science has taken a massive step toward offering a genuine, lasting cure for end-stage bladder disease.[2][5]