Surgeons almost always leave the old kidneys in place during a transplant because removing them would mean a bigger, riskier operation with no clear benefit for most patients. The new kidney is not placed where the old ones sit; it goes into the lower abdomen, tucked into the pelvis near the hip bone, where it can be connected to accessible blood vessels and the bladder. Since the native kidneys are not physically in the way and removing them carries real surgical dangers, taking them out is reserved for specific medical reasons rather than done as a matter of routine.
Where the New Kidney Actually Goes
Your two native kidneys sit deep in the back of the abdomen, high up near the ribcage, nestled against the spine on either side. Reaching them surgically requires cutting through layers of muscle and working around other organs. A transplant surgeon avoids all of that by placing the new kidney in the iliac fossa, a shallow depression in the pelvis just above the groin, usually on the right side. The surgeon connects the new kidney’s artery and vein to the iliac vessels (the large blood vessels heading to the leg) and attaches the ureter directly to the bladder. This location is closer to the surface, easier to access, and allows the operation to be done through a single lower-abdominal incision rather than a deep approach from behind.
Because the transplanted kidney sits in a completely different part of the body from the native kidneys, there is no anatomical reason to remove the old ones. They are not competing for space in a typical patient, and disturbing them would require a separate, more invasive surgical procedure on top of the transplant itself.
The Surgical Risk of Removing Native Kidneys
Taking out a kidney, even a diseased one, is a significant operation. It involves clamping and cutting major blood vessels, separating the kidney from surrounding tissue, and managing the potential for bleeding, infection, and damage to neighboring structures. Adding a native nephrectomy (kidney removal) to a transplant operation or doing it as a separate procedure doubles the surgical exposure. For patients who are already in fragile health from years of kidney disease and dialysis, this extra risk is hard to justify when the old kidneys are simply sitting there causing no immediate harm. Graft nephrectomy, the removal of a failed transplant kidney, has itself been associated with high rates of complications, and similar risks apply to removing native kidneys.
Embolization, a procedure where a radiologist blocks the blood supply to a kidney using small particles threaded through a catheter, has been explored as a less invasive alternative to surgical removal in some situations. One center reported using renal vascular embolization over a seven-year period as a substitute for surgical nephrectomy in patients experiencing graft intolerance syndrome, precisely because the morbidity and mortality of open nephrectomy were considered too high.1PubMed. Nonfunctioning renal allograft embolization as an alternative to graft nephrectomy: report on seven years’ experience The same logic applies to native kidneys: if you can avoid an operation, you should.
Native Kidneys Sometimes Still Work a Little
Even kidneys that have failed badly enough to require a transplant are not always completely dead. Many retain some residual function, producing small amounts of urine and continuing to filter a fraction of the blood’s waste. This leftover output, called residual native kidney function, can actually help the transplanted kidney by sharing the workload. In one documented case, a perfusion scan showed that the patient’s native kidneys were still contributing roughly a third of total kidney function even after transplant.2Journal of the American Society of Nephrology. Residual Native Kidney Function after Kidney Transplant (KT): Unusual Complications That case was unusual because so much native function actually caused problems (the native kidneys’ excessive output led to chronic volume depletion and stressed the transplant), but it illustrates the point that the old kidneys are not necessarily inert organs. Removing them would eliminate whatever residual contribution they are making.
Beyond filtration, native kidneys continue to produce erythropoietin, a hormone that stimulates red blood cell production. They also play a small role in vitamin D metabolism and blood pressure regulation. These contributions are modest in a person with advanced kidney disease, but they are not zero, and removing the organs would eliminate them entirely.
What Happens to Native Kidneys Over Time
Once a transplanted kidney takes over, the native kidneys tend to gradually shrink. In patients with autosomal dominant polycystic kidney disease (ADPKD), where the kidneys are massively enlarged with fluid-filled cysts, researchers have measured a significant reduction in native kidney volume after a successful transplant.3PubMed Central. Change in kidney volume after kidney transplantation in patients with autosomal polycystic kidney disease The explanation is straightforward: once normal kidney function is restored by the graft, the native kidneys progressively lose whatever residual function they had. They atrophy, becoming smaller and less metabolically active. In patients without polycystic disease, the native kidneys were already small and scarred from whatever disease destroyed them, and they continue to wither quietly over the years. For most transplant recipients, the old kidneys become essentially inert tissue that causes no symptoms.
When Surgeons Do Remove Native Kidneys
There are specific situations where leaving the native kidneys in place is not an option. These represent the minority of transplant cases, and the decision to remove is driven by symptoms or conditions where the old kidneys are actively causing harm.
Polycystic Kidney Disease and Space Constraints
ADPKD causes kidneys to grow to enormous size, sometimes weighing several kilograms each and filling much of the abdominal cavity. In many of these patients, the native kidneys physically leave no room for a transplant to be placed. A study of nephrectomy in ADPKD transplant candidates found that the leading indication for removal was lack of intra-abdominal space for graft implantation, followed by cyst infection, chronic pain, and hemorrhagic cysts.4PubMed. Nephrectomy in Kidney Transplant Candidates With Autosomal Dominant Polycystic Kidney Disease Another study looking at both pre-transplant and post-transplant nephrectomy in ADPKD patients found similar patterns: recurrent symptomatic bleeding, lack of space, and pain severe enough to affect quality of life were the main drivers. After transplant, back pain and abdominal pain became the most common reasons patients eventually needed the old kidneys removed.5PubMed Central. Native Nephrectomy in Renal Transplant Recipients With Autosomal-Dominant Polycystic Kidney Disease
The timing matters. Removing one or both polycystic kidneys before the transplant means the patient has to endure two separate major surgeries, and losing any residual kidney function between the nephrectomy and the transplant can make dialysis harder. Some centers prefer simultaneous nephrectomy and transplant, while others wait and remove the native kidneys only if they start causing trouble after the transplant is in place. There is no universal consensus on the best approach.
Recurrent Infections
Native kidneys can harbor infections, particularly in patients with structural abnormalities of the urinary tract or in ADPKD patients whose cysts become repeatedly infected. Cyst infections are a recognized complication after transplant in ADPKD patients, and having a history of cyst infections before transplant roughly triples the risk of experiencing them afterward.6PubMed Central. Incidence, Risk Factors and Outcomes of Kidney and Liver Cyst Infection in Kidney Transplant Recipient With ADPKD If antibiotics cannot control these infections and they keep coming back, nephrectomy may be the only way to eliminate the source. In patients with conditions like severe vesicoureteral reflux, where urine flows backward from the bladder into the kidneys, the native kidneys can act as a reservoir for chronic or recurrent urinary tract infections. For these patients, removing the old kidneys before or after transplant can prevent future episodes.
Severe Uncontrollable Proteinuria
Some native kidneys continue to leak massive amounts of protein into the urine, a condition that can cause fluid imbalance, nutritional problems, and blood clots. When native proteinuria is heavy enough to threaten a patient’s health, nephrectomy is considered. This is relatively uncommon but comes up in specific glomerular diseases where the native kidneys dump protein even though they have largely stopped filtering waste.
Cancer Risk in Native Kidneys After Transplant
Transplant recipients take immunosuppressive drugs to prevent their body from rejecting the new kidney. These medications dampen the immune system’s ability to detect and destroy abnormal cells, which raises the risk of developing certain cancers. Renal cell carcinoma (RCC), the most common type of kidney cancer, can arise in the native kidneys of transplant recipients, and these patients face an elevated risk compared to the general population.7PubMed. Features and outcomes of renal cell carcinoma of native kidneys in renal transplant recipients
Interestingly, the main risk factor does not appear to be the immunosuppressive drugs themselves. A condition called acquired cystic kidney disease, where small cysts develop in the native kidneys after years of kidney failure and dialysis, is strongly associated with later cancer development. One study found acquired cystic disease in about three-quarters of transplant patients who developed renal cell carcinoma, and concluded that this cystic degeneration and the original kidney disease (particularly certain types like analgesic nephropathy) were the primary risk factors, not the immunosuppressive regimen itself.8Clinical Transplantation. Risk of renal cell carcinoma after kidney transplantation
This cancer risk is why transplant teams typically monitor native kidneys with periodic imaging, usually ultrasound, after the transplant. The goal is to catch any new growth early, when it can be treated by removing the affected native kidney rather than dealing with advanced cancer. Routine prophylactic removal of native kidneys solely to prevent a possible future cancer is not standard practice; the risk is elevated but still relatively low in absolute terms, and the surgery would expose every transplant patient to harm to prevent cancer in a small fraction.
Pediatric Transplant Patients
Children receiving kidney transplants present a somewhat different calculus. In one study of pediatric patients who underwent native nephrectomy before transplant, nearly half had structural abnormalities of the kidneys and urinary tract, while others had conditions like cystinosis, focal segmental glomerulosclerosis, or congenital nephrotic syndrome. The decisions to remove native kidneys were driven by heavy urine output (polyuria), large protein losses, or recurrent urinary tract infections.9PubMed Central. Native nephrectomy prior to pediatric kidney transplantation: biological and clinical aspects
In children, excessive native urine output can be a particular problem because it makes fluid management difficult. A child producing large volumes of dilute urine from native kidneys that cannot concentrate it properly may become chronically dehydrated, and the transplanted kidney has to work against this ongoing loss. For these patients, removing the native kidneys before transplant simplifies post-operative care and gives the new kidney a more stable environment in which to function. The threshold for native nephrectomy tends to be lower in pediatric patients than in adults, partly because the long-term stakes of getting the transplant off to a strong start are especially high in a child who will ideally live decades with their graft.
Hypertension and the Native Kidneys
High blood pressure is extremely common after kidney transplantation. One contributor can be the native kidneys themselves. Even shrunken, diseased kidneys continue to produce renin, an enzyme that drives up blood pressure through the renin-angiotensin system. In some patients, the native kidneys produce renin at inappropriate levels, contributing to post-transplant hypertension that is difficult to control with medication alone. When a transplant recipient has persistently high blood pressure that does not respond to standard drug therapy, and the native kidneys are identified as the source, nephrectomy can be considered. This situation is uncommon but well-recognized.
Most post-transplant hypertension has multiple causes, including the immunosuppressive drugs (calcineurin inhibitors like tacrolimus are notorious for raising blood pressure), the transplanted kidney itself if it has any degree of rejection or arterial narrowing, and pre-existing vascular disease. Removing native kidneys helps only when those kidneys are a significant contributor, which is a determination made through clinical evaluation and sometimes renin measurements. It would make no sense to remove them if the blood pressure problem is coming from the medications or the graft.
Psychological and Practical Aspects
Many patients are surprised to learn they will have three kidneys after the transplant. It sounds odd, and some people worry that the old diseased kidneys will somehow interfere with the new one. In practice, the native kidneys and the transplant operate independently. Blood flows to each on its own vascular supply, and urine drains through separate pathways. The transplanted kidney’s ureter is connected directly to the bladder, while the native kidneys’ ureters continue to drain whatever small amount of urine they still produce through their original connections.
From a practical standpoint, having the native kidneys in place means transplant patients undergoing imaging studies may see three kidneys on their scans. Radiologists and emergency physicians need to be aware that the transplanted kidney is in the pelvis, not in the usual kidney location, so that any new imaging is interpreted correctly. If a transplant recipient shows up at an emergency room with abdominal pain, knowing the anatomy prevents confusion about what structures are where. Some patients carry cards or wear medical alert identification noting their transplant and the location of the graft for exactly this reason.
Another occasional surprise: native kidneys that appeared dead can sometimes partially recover function if the underlying disease process is halted, though this is rare and unpredictable. More commonly, the native kidneys simply sit quietly for the rest of the patient’s life, causing no trouble and requiring no attention beyond periodic surveillance imaging to watch for acquired cysts or tumors.