Overview of Kidney Transplantation
Kidney transplant is often the best treatment for people suffering from severe kidney disease. The field of kidney transplantation has progressed a lot in the past 50 years. Studies show that people with severe kidney disease who are placed on a waiting list for a kidney transplant and eventually get one, live longer than those who continue on kidney dialysis.
Moreover, people who receive kidney transplants often have a better quality of life and can live up to 10 years longer than those who continue on dialysis. With the first successful kidney transplant carried out by Dr. Joseph Murray in 1954, the field has seen significant advancements. This has allowed for a wider range of potential donors and recipients.
Anatomy and Physiology of Kidney Transplantation
The kidneys are a pair of important organs situated at the back of the body. They are located underneath the diaphragm (the muscle that helps in breathing) and the 12th rib. The right kidney is surrounded by parts of the gut, liver, and pancreas. On the other hand, the left kidney is adjacent to another part of the gut, specific blood vessels, pancreas, and the spleen, connected by a tissue known as the lienorenal ligament. Both kidneys are resting on a muscle called the psoas muscle. At the upper part of both kidneys, there are adrenal glands which produce hormones that help to regulate metabolism, immune system, blood pressure, response to stress, and other essential functions.
Within the kidneys, several structures are arranged in order: the renal vein (which transports blood out of the kidney), renal artery (which brings blood to the kidney), and the ureter (the tube that carries urine from the kidneys to the bladder). The renal arteries come from a large artery called the aorta, which carries oxygen-rich blood from the heart to the body. The right renal artery moves behind a large vein called the inferior vena cava. The renal artery further divides into an anterior and posterior division, supplying blood to different parts of the kidney. If these arteries get blocked or injured, it can cause damage to the kidney due to a lack of blood supply.
The renal vein, which takes blood away from the kidney, is typically located in front of the renal artery. Like the arteries, the veins also branch out into smaller divisions. The right renal vein, being closer to a large vein known as the vena cava, drains directly into it and has no tributaries, or smaller veins draining into it. However, the left renal vein has several tributaries. The left renal vein also passes in front of the large aorta artery to reach the vena cava. Because of its extra length, the left kidney is usually preferred when a kidney donation from a living person is needed, as it simplifies the surgical connection process.
Why do People Need Kidney Transplantation
The number of people suffering from severe kidney disease, also known as end-stage renal disease (ESRD), is rapidly increasing. The main triggers of this condition are diseases like diabetes and high blood pressure. However, there are other reasons why a person might have kidney disease, such as chronic or acute lack of blood supply to the kidneys (prerenal), disease within the kidney itself (intrinsic renal) like glomerulonephritis or focal-segmental glomerulosclerosis, or issues that develop after the kidneys (postrenal) like reflux nephropathy, or blockages.
Patients diagnosed with a severe level of chronic kidney disease (CKD), often referred to as stage 4, should be in regular contact with a kidney specialist or “nephrologist”. A telltale sign of reaching stage 4 is when the kidneys’ filtration rate, or the speed at which the kidneys clean the blood (glomerular filtration rate – GFR), is less than 30 milliliters per minute. At this stage, patients need education about the possible progression to kidney failure, including possible treatments like kidney transplantation.
If there are no health issues preventing transplantation, the kidney specialist will recommend the patient to a transplant center. Alongside this, they will also prepare the patient for possibly starting dialysis, a treatment that helps to clean the blood when the kidneys can no longer do the job. It’s important to note that people who receive a kidney transplant generally live longer than those who stay on dialysis. Furthermore, the longer a person is on dialysis, the less likely the chances are of achieving the best possible health outcome.
When a Person Should Avoid Kidney Transplantation
There are some situations where a person cannot undergo a kidney transplant:
If they can’t handle surgery due to severe heart or lung conditions, currently have cancer, have an active infection, participate in ongoing drug abuse, or if they’re grappling with severe mental health issues that aren’t under control.
Other factors that might make a kidney transplant less appropriate could differ based on the hospital and the specific part of the world. These might include being extremely overweight, with a recommended body mass index (BMI) of less than 40 kg/m. Other issues could involve not sticking to a dialysis schedule or taking their required medicines, having poor overall physical strength (frailty), dealing with mental health problems, or having a shorter life expectancy than the time they’d spend waiting for a kidney.
Preparing for Kidney Transplantation
Before a patient with kidney issues can have their transplant, doctors have to evaluate their health condition carefully. This is because kidney problems can lead to other health conditions, and the patient needs to be strong enough to cope with the operation itself. Here are some of the things they check:
1. The health of the heart: Most patients need to have specific tests done to check on the health of their heart. This is because heart disease is the leading cause of death after a kidney transplant. If heart disease is detected, it should ideally be treated before the transplant takes place.
2. History of stroke: Doctors need to check if the patient has had any form of stroke in the past. They will also look for any signs of artery disease in the patient’s neck. If needed, further tests and treatments may be performed before the transplant.
3. Patient’s fitness: Doctors use various tests to determine if the patient is physically able to handle the transplant. This is especially true for older patients.
4. Stomach issues: Anyone with a history of colon cancer or who is over 50 years of age should have a colon check-up. Also, people with viral liver diseases may need to have a liver-kidney combined transplant.
5. Blood disorders: It’s crucial to evaluate patients with a history of blood clotting. They may need drugs to prevent blood clots. If they have bleeding problems, a series of blood tests should be performed.
6. Infections: Any active infection means that a kidney transplant cannot be done. Tests for many viral infections are usually done, and all vaccines should be up-to-date.
7. History of cancer: If a patient has had cancer, doctors usually require a period of being cancer-free, usually between 2-5 years before a transplant. This is to minimize the risk of cancer returning after the operation.
8. Matters of the lung: Some patients may need to be checked for lung conditions. If severe conditions are discovered, treatment or precautions will be carried out before surgery.
When it comes to choosing a kidney for transplant, there are two types: living or deceased.
Deceased donors are further classified – some are brain dead, while others donate their organs after their heart stops.
The quality of kidneys from deceased donors is evaluated measuring various factors in a kidney donor profile index. Despite the seemingly low quality, studies have shown that even a transplant from a high-KDPI kidney can still improve life quality and save costs compared to remaining on dialysis.
Kidney donation from a living person remains the best choice and offers the best survival rates. Eligible donors are between the ages of 18 and 70 without active diseases, sufficient kidney function, and meet specific health criteria.
Regarding the long-term impact on living kidney donors, while earlier studies indicated donation does not affect the donor’s kidney health or survival, more recent studies found a slightly higher risk of kidney problems after donation. This risk, however, is on par with the risk faced by the general public.
How is Kidney Transplantation performed
Transplant surgery is a two-part process that involves both the donor and the recipient of the organ. This process can be done through a less intrusive method (also known as a minimally invasive approach) or, less often, via open surgery for the living organ donor. The recipient will always undergo an open surgery where the kidney is placed in a new location (heterotopically) in their pelvis. The kidney’s veins and arteries are then connected to the recipient’s external iliac vessels (the major blood vessels in the pelvis) and the ureter (the tube through which urine passes from kidney to bladder) is connected to the bladder. During this process, the iliac vessels, which are usually uncovered by shifting the peritoneum (abdominal lining) inwards, are connected to the kidney. However, the kidney can also be placed within the peritoneum.
There are two main types of minimally invasive surgery: laparoscopic and robotic. Both these methods can be used to remove either kidney. The surgeon first enters the abdominal cavity to place the surgical tools. If it’s the left kidney, the ureter and gonadal vein (a vein found near the genitals) are found at the pelvic brim (the edge of the pelvic bone) once the left colon is disconnected from its peritoneal attachments. The surgeon then follows this track upwards to find and isolate the renal vein and artery. The adrenal gland (small gland on top of each kidney) is separated from the top part of the kidney and its connecting vein is divided. Once the kidney is free from all other attachments except its artery, vein, and ureter, a slightly larger cut is made for swift extraction. The part of the ureter near its end is divided, and the kidney’s blood vessels are divided with a special stapler. The process differs slightly depending on which kidney is being removed. For the right kidney, the liver is shifted aside and the right colon and duodenum (the first part of the small intestine right after the stomach) are partially shifted to access the kidney.
In the process of open surgery for removing the kidney from a living donor, a cut is made below the ribcage and the space behind the abdominal cavity is exposed. The ureter is traced down to the iliac vessels and disconnected there before the kidney is extracted. The kidney is left attached only to its blood vessels, and once the recipient team is ready, the renal artery and vein are cut, and the kidney is transferred to the back table for further preparation. Anything left over from the surrounding fatty tissue is trimmed while preparing the kidney for implantation.
After removing the kidneys, the organ is preserved before it can be implanted in the recipient. As soon as the donor’s heart stops and normal blood circulation halts, the kidneys experience ischemia, which is a lack of blood supply. The kidneys need to be kept on ice as much as possible during this phase, known as cold ischemia, to reduce their metabolic demand and limit damage. Another phase, known as warm ischemia, is more harmful to the organ and takes place after the organ is removed from the cold storage until it is connected to the recipient’s blood vessels. This phase also happens during the organ donation process when the patient’s heart stops, and the main blood vessel in the heart is infused with a preservative solution and cooled with ice.
During cold ischemia, the organ is kept in a static cold solution, commonly known as the University of Wisconsin Preservation Solution in the United States. Alternatively, organs can be put on a machine for preservation, a newer technology, which some studies suggest could reduce the risk of delayed graft function (when the transplanted organ does not work immediately). This machine can also be used to assess the patency (adequate blood flow) of the organ’s blood vessels, focusing on flow and resistance.
Possible Complications of Kidney Transplantation
Like with any type of surgery where the blood vessels are involved, bleeding is a possible risk, both during the surgery and in the early stage of recovery. You might not see the typical signs of bleeding. For instance, patients may not show a rapid heart rate—a usual response to loss of blood—because they are often on beta-blockers. Also, they can have high blood pressure rather than low, because of effects on the organ being affected. Common complaints can be of sudden pain in the side and there might be a noticeable swelling near the surgery site. If doctors suspect such a bleeding, they might need to do another operation. Keep in mind, the bleeding might be kept in check by the kidney because of the way it is positioned, a protection not found when the new kidney is placed inside the abdomen.
Blockage in the renal vein, which carries blood away from the kidney, is fortunately a rare issue but it is linked with a high chance of losing the new kidney. Symptoms can include passing blood in urine, sudden decrease in urine output, and the new kidney not working properly. Blockage in the arteries is even rarer and usually more serious, causing similar symptoms. An ultrasound can usually diagnose these issues and should be ordered if there is a sudden decrease in urine output. Doctors look out for vascular complications early after the operation due to technical problems or injuries from the surgical clamp.
Infections are common after surgery because patients are given drugs to suppress their immune system. This is more of a risk in the first 3 to 6 months after the operation when the immune-suppression is at its most intense. Usual infections in the first month after a transplant include urinary tract infections and infections at the surgery site. Doctors must be on the lookout for rare or opportunistic infections, particularly in the following months. Common viruses to check for include cytomegalovirus, Epstein-Barr virus, and polyomavirus (BK-type). Patients are usually given preventative antivirals and antibiotics in the first 3 to 6 months to lessen the risk of infection.
Arterial Stenosis, or narrowing of the arteries, is second stage complication and often doesn’t show symptoms. It’s usually found through an ultrasound if the new kidney is not performing well (higher levels of creatinine in the blood). Diagnostics and treatment can be performed using angiography, and an attempt can be made to correct it using angioplasty, a procedure to widen the arteries.
Formation of a lymphocele, a pool of lymph fluid, can happen if the lymphatic vessels are disrupted during the exposure of the vessels in the pelvis. Patients can present with pain and swelling over the transplanted kidney. This can be treated with a procedure to drain the lymphocele. If the lymphocele keeps coming back surgical intervention may be required.
A urinoma, which is a collection of urine outside of the urinary tract, can occur within the first week of transplantation. You may feel pain and see swelling at the surgery site. An increased creatinine level on a fluid test confirms this diagnosis. Many centres put in a ureteral stent (a small tube used to prevent or treat obstructions of the urine flow from the kidney) to prevent this complication. If a urine leak happens, bladder decompression with a Foley catheter (a flexible tube used to empty the bladder and collect urine) is usually all that is needed. Sometimes, surgical operation and fixing of the joined areas between ureter and bladder may be needed.
What Else Should I Know About Kidney Transplantation?
Prior to the availability of kidney transplants, individuals with end-stage kidney disease, a medical condition where the kidneys stop working properly, didn’t have great treatment options. However, things took a positive turn when a treatment method called hemodialysis was developed. This method helps to improve survival rates by artificially cleaning the blood when the kidneys can’t.
The introduction of kidney transplantation was an even bigger game changer. Studies showed that patients suffering from severe kidney disease had a better chance of surviving long-term if they received a kidney transplant compared to those who only relied on dialysis. Added to that, patients who had a transplant also enjoyed a significantly better quality of life.
Moreover, a remarkable advantage of undergoing a kidney transplant is that it can potentially add an extra 10 years to a patient’s life compared to staying on dialysis. This is a huge benefit that highlights the important role of kidney transplants in treating end-stage kidney disease.
