Overview of Percutaneous Nephrostomy
Percutaneous nephrostomy, or PCN, is a medical procedure that was first introduced by a doctor named Willard Goodwin in 1955. This procedure is less invasive than traditional surgery and can be used as a temporary or permanent solution for patients with a condition known as hydronephrosis. Hydronephrosis is when one or both kidneys become swollen due to a buildup of urine. The PCN procedure is done with the help of an x-ray to guide the doctor.
SInce its introduction, the PCN procedure has become quite common. However, it’s mostly performed by radiologists now. This shift happened in the late 1970s, around when ultrasound imaging technology improved. This technology allowed doctors to better see the kidneys using a method called a cross-sectional approach. This means they can ‘slice’ the image into sections, making it easier to get a detailed view of the kidneys.
Anatomy and Physiology of Percutaneous Nephrostomy
The human kidney is typically positioned in between two parts of our spine, specifically the T12 and L3 vertebrae. The right kidney is a little bit lower than the left one. Each kidney is tilted in a unique manner; the upper end of the kidney is pointed towards the back and the inside and the lower end is pointed towards the front and the outside. Imagine the kidneys as leaning back at a 30 to 50-degrees angle from the front of your body and turned inward at the same angle from the middle of your body.
Usually, the right kidney is a bit lower than the left one. When a person lies on their stomach, both kidneys move slightly upward.
PeriCatheter Nephrostomy (PCN), which is a procedure to drain the kidney, could potentially harm several organs and structures around the kidney including the protective layer around the lung (pleura), the muscular sheet that helps us breathe (diaphragm), the colon, spleen, and liver. Among these, injuries to the pleura and diaphragm are most common. To prevent injury to the pleura, which extends to the lower edge of the 12th rib of the spine, it’s best to place the PCN below the 12th rib. If placed above, it will likely puncture the diaphragm.
Now let’s talk about the inner structure of the kidney. It’s comprised of 8 to 15 small chambers (minor calyces) that come together to form larger chambers (major calyces) which produce a single hollow structure (renal pelvis) that connects to a tube (ureter) to carry urine from the kidney. The kidney gets its blood supply from a single artery that divides into two branches. However, everybody is unique, and due to different genes or early development reasons, a person’s kidney can have slightly different arrangements of these structures.
An interesting detail about the kidney is that it has a relatively less blood-supplying area, often referred to as Brodel’s line (named after medical illustrator Max Brodel). This area is at a 20 to 30-degree angle away from the middle of the body, and puncturing this area instead of others while doing a kidney procedure can reduce the risk of bleeding.
Lastly, the kidney is located inside the perirenal space, which is an isolated compartment separated by a sealing tissue (fascia) from all other internal organs except for the adrenal gland. So, to reach the kidney, doctors maneuver medical instruments through this space and have to be careful of not touching the pleura, blood vessels under the ribs (subcostal arteries), and nearby structures like the first part of the small intestine (duodenum) and parts of the large intestine (ascending on the right and descending on the left).
Why do People Need Percutaneous Nephrostomy
There are several reasons why a person might need PCN (Percutaneous Nephrostomy), which is a procedure that can help drain urine from your kidneys when something is blocking the normal path to your bladder:
One of the main reasons a person might need PCN is to help drain an obstructed kidney, which is a kidney that is blocked and unable to drain urine properly. Obstructions can occur for various reasons, such as pregnancy, tumors, or certain diseases. In most cases, getting a PCN will not be an emergency, unless the kidney has been blocked for a long time. If the kidney has been blocked for more than 12 weeks, there is a high chance that the kidney function will not fully recover.
Another reason for getting a PCN is in emergency cases where an infection has occurred due to a blockage, which can be life-threatening and cause permanent damage to the kidney. In these cases, the patient might also have a stent (a tube) placed inside the ureter (the tube that connects your kidney to your bladder) to keep it open.
PCN can also be a first step for treating kidney stones, especially large ones or if the patient has an abnormal anatomy or connected diseases, or is pregnant. The procedure can create a pathway through which various tools can be used to break down or remove the stones. Plus, PCN can also be used to help prevent stone formation by giving doctors direct access to the kidney where they can introduce medications to treat or prevent the stones.
During pregnancy, kidney stones are quite common and usually very painful. Both PCN and stents are considered safe to use for pregnant patients, but they both have their pros and cons. Stents can cause urinary infections, can be uncomfortable, and need to be replaced frequently, while PCN can lead to septic complications and can easily become dislodged.
PCN can also help heal injuries caused by a leaking kidney or a fistula (abnormal connection between the kidney and another organ) by rerouting urine away from the infected area. Other cases in which PCN might be used include ureteral diseases such as strictures (narrowing), fistulas, or infections. The procedure provides a less invasive way for doctors to treat these conditions.
Lastly, PCN can be essential for helping doctors make a certain diagnosis, particularly in patients with only one functioning kidney. For these patients, the PCN procedure allows a detailed inspection of the kidney and ureter, and can provide valuable information that cannot be obtained through imaging alone.
When a Person Should Avoid Percutaneous Nephrostomy
Sometimes, it might not be safe to perform a certain procedure, known as PCN, and it’s better to delay it. There are no situations where it’s absolutely not allowed, but there are cases where it’s not the best option.
Before beginning any treatment, doctors tend to choose the least risky options first. If possible, a treatment method that doesn’t require making a cut in the body should be tried. However, if someone is not expected to live very long, it’s better to reconsider if the PCN is really necessary.
Untreated urine infections could potentially make the PCN risky, so it’s typically delayed in these situations.
Also, sometimes the procedure can be postponed if the hollow spaces in the kidneys (calyces) may get bigger with a short delay. This could make the procedure simpler and safer. Before deciding on the procedure, doctors need to consider things like whether the patient bleeds excessively or could face complications from being given sedatives or relaxants. If the bladder is blocked and affects kidney function, leading to a high level of potassium substance (hyperkalemia) in the blood, it could cause dangerous disturbances in heart rhythm. Before starting PCN, the excess potassium should be removed with blood-filtering treatment (hemodialysis).
Before the procedure, it’s important to understand what the patient is okay with. The procedure requires a foreign object to be implanted in the body for weeks or months and requires regular care. This means that a person might need prolonged nursing or support from their family, which could limit their daily activities. If a patient is not willing to accept this or the risks of the procedure, this poses a barrier to the procedure.
Before the procedure, doctor needs to address specific issues, such as the risks of bleeding excessively and complications from sedatives, and will try to manage these risks as much as possible. The Society of Interventional Radiology has provided advice about when and how to stop blood thinning medications before starting interventional radiology procedures which may cause bleeding – among them, PCN is a high-risk level 3 procedure. These recommendations are discussed later under “Preparation.”
Preparing for Percutaneous Nephrostomy
The Society of Interventional Radiology (SIR) provides recommendations on how to safely stop certain medications that make the blood thin before a radiology procedure. This is because these medications can increase the risk of bleeding during the procedure. The SIR rates procedures based on their risk levels, from 1 being the lowest risk to 3 being the highest risk. When it comes to radiology procedures for kidney-related issues, it is put at risk level 3, which is the highest.
The patients are advised to maintain certain levels of blood clotting and platelets, a type of blood cell that helps in clotting, to ensure that they don’t bleed too much during their procedure. They should also stop medication like aspirin for 5 days before the procedure, and in some cases, delay their procedure for 24 hours after their last dose of blood thinners like Enoxaparin.
Anesthesia, which is used to make patients sleep during the procedure and avoid feeling any pain, also has its own set of risk factors. Many hospitals require doctors to assess the patient’s overall health and comfort level with anesthesia using a specific scoring system. If they find that the patient has a higher risk, they recommend a special consultation with an anesthetic expert before they agree to the procedure.
If there’s a chance that the patient may have an infection, antibiotics are usually given an hour before the procedure. They protect against common types of bacteria. There are several options for antibiotics, all of which help prevent the procedure from causing an infection.
Kidney stone procedures may also include a urine test. This is because these tests are more accurate in predicting whether a patient may develop a serious infection after the procedure. Some studies even suggest that patients should be on antibiotics for a week before their kidney stone procedures, even if their initial urine culture is negative.
Sometimes, patients may have imbalances in their system due to the kidneys not working well. Such imbalances should be corrected before the procedure to avoid any risks. If conditions like hyperkalemia, which is higher than normal potassium levels in the blood, or symptoms of it are present, then an electrocardiogram (ECG), a test that measures the electrical activity of the heartbeat, may be recommended.
Finally, good surgical precision is vital to avoid any complications. A CT scan may be necessary in certain cases to have a better understanding of the person’s anatomy before the procedure. Furthermore, ultrasound can be used to check that the colon, another part of the digestive system, is not in the way when the procedure is being performed. In brief, thorough preparation and planning beforehand can significantly reduce complications and improve the outcome of the procedure.
How is Percutaneous Nephrostomy performed
Choosing a target kidney area is done using ultrasound or a special type of x-ray called fluoroscopy, or sometimes a combination of both. To help see the inside structure of the kidney more clearly, a dye or contrast can be injected into your veins or through a tube into your ureter, the tube that carries urine from your kidneys to the bladder.
The spot where the skin is pierced to access the kidney depends on the unique structure of your kidney, the problem that needs to be addressed, and whether additional procedures, like percutaneous nephrolithotomy (PCNL), a procedure used to remove kidney stones, are also planned. Ideally, the skin is pierced below the 12th rib (the last rib on your side) to avoid damage to the lung lining or diaphragm. An excessively medial (closer to the spine) entry point can cause discomfort and pain as the back muscles can bend the tube used in the procedure and make lying on your back uncomfortable. On the other hand, an excessively lateral (closer to the side) entry point could increase the risk of accidentally hurting the colon.
Typically, the best entry point is a part of the kidney called the posterior calyx which is usually chosen to minimize bleeding. This is because of its location along an area called Brodel’s line, which has lesser blood vessels. It’s not ideal to access through the kidney tube or renal pelvis as that increases the risk of blood vessel injury.
If a PCNL is envisaged, coordination with a urologist is crucial in order to position the entry point in such a way as to enhance stone fragmentation and removal. It is preferred that the entry point should provide a straight path to the area of the largest stone, especially if rigid instruments are being used, as this can significantly aid in the subsequent stone fragmentation and removal. For certain complex cases, such as stones in the lower or multiple areas of the kidney, it’s recommended to access the kidney from the upper section. If the entry point is above the 12th rib, an intercostal approach, a chest x-ray is recommended afterwards to check for potential issues.
The most common method for inserting the needle is the “eye of the needle” approach. This involves using the C-arm (a flexible, C-shaped imaging scanner) or fluoroscope such that the needle is aimed directly at the target calyx or stone and is parallel to these structures. The correct depth for the needle is controlled by rotating or angulating the x-ray unit.
There are two strategies for needle entry, a one-stick or two-stick technique. In the one-stick method, if a patient has a visible, radiopaque stone, you can use it as a target for the needle stick. In the two-stick method, the first needle stick is used only to inject contrast dye into the kidney chambers so that the kidney structure is visible and the final needle stick could be accurately directed to the desired spot. The initial needle stick typically involves a smaller needle directly aimed at the renal pelvis. Air or carbon dioxide can also be injected into the renal pelvis which helps to highlight the posterior calyces (kidney’s urine collection chambers), providing a clear target for the procedure.
An 18 or 21 gauge needle is inserted, followed by aspiration of urine from the renal pelvis. A guidewire, a thin wire that helps guide the catheter into place, is then placed through the needle. If a kidney stone is present, the needle can be aimed directly at the stone. The 18-gauge needle can easily accommodate a 0.035-inch guidewire, while with a 21-gauge needle, a transitional dilator (a tube used to enlarge the entry) is required. Studies found that 18-gauge needles were no more likely to cause bleeding complications than 21-gauge needles when used for PCN access.
Subsequently, a guidewire is positioned to anchor ideally in the ureter, though in some cases due to restrictions, it might have to be directed to a different calyx or the renal pelvis. If required, an angled catheter is used to redirect the guidewire. Once the guidewire position is determined and fixed, sequential, transitional dilators or a balloon dilator are used to make way for the eventual nephrostomy catheter, which typically starts at about 8 French size (a measurement used in medicine for the diameter of tubes). Stents that are placed via the urethra typically range from 6 or 7 French, but they can go up to a maximum of 8 French.
Possible Complications of Percutaneous Nephrostomy
The Society of Interventional Radiology has published data that suggests complicated outcomes from percutaneous nephrostomy (a type of kidney surgery) happen in about 2-10% of cases. These complications can include:
– Blood poisoning, also known as sepsis.
– Uncontrolled bleeding, leading to a collection of blood under the skin, or formation of a false blood vessel.
– A condition where air leaks into the space between the lungs and chest wall, known as pneumothorax.
– Accidental puncture of nearby organs.
– Leakage of urine or formation of a urine-filled cyst.
– In rare cases, the procedure could lead to death.
Touching blood vessels during this surgery is a common occurrence. This usually leads to a process where blood normally solidifies, and bleeding eventually fully stops within 2 to 3 days. Sometimes minor bleeding after the procedure is expected and happens in about 95% of cases. However, more significant bleeding needing a blood transfusion can happen in about 1 to 4% of patients, while small collections of blood found outside the blood vessels are identified in around 13% of patients.
For patients who are stable:
– If it’s clear that a blood vessel is bleeding (for example, there’s bright red blood coming out of the tube used in the procedure), the patient should get immediate treatment to block the blood flow.
– If it’s suspected that there’s bleeding (such as consistent blood in urine, decreasing blood count levels, or unstable vitals), a CT scan (a type of body scan that uses x-rays) can be used to identify the source of the problem. After that, another procedure can be carried out to find the exact location of the bleeding and treat it.
If the patient’s condition is not stable:
– A discussion must be had with the radiologist (a doctor who specializes in diagnosing and treating diseases and injuries with medical imaging) and surgeon to decide if the patient should go to surgery, get a procedure to block the blood vessel, or get both if possible.
This procedure can potentially allow bacteria to enter the urinary tract. Although it is done to treat a blockage that is causing blood poisoning, it could also cause blood poisoning itself. To prevent this, the catheter (a tube inserted into the body to drain or inject fluid) used in the procedure should be changed every 2-3 months. It’s also important to use a catheter that is less likely to get blocked. Kidney inflammation caused by bacteria can be treated with antibiotics.
Infections related to this procedure should be treated with specific antibiotics based on the type of bacteria causing the infection. After the right antibiotics have been given, it is recommended that the tube used in the kidney surgery be changed within four days.
Percutaneous nephrostomy tubes can sometimes get blocked due to build-ups commonly made of calcium phosphate. Temporarily, flushing the catheter can help with an immediate blockage, but even normal flushing doesn’t seem to affect the rate of this blockage buildup. The only factor that has been shown to reduce the rate of tube blockages is increased fluid intake. For pregnant women, this catheter should be changed every 4-6 weeks. For most other patients, routine changes every 3 months are generally recommended.
What Else Should I Know About Percutaneous Nephrostomy?
Undergoing PCN (a procedure to insert a small tube through your skin into your kidney) usually succeeds 95% of the time when the kidney is enlarged but doesn’t have any stones. If your kidney isn’t enlarged, the success rate is typically around 80%.
Here are some advantages of this procedure:
* It can help to save cells in your kidney right away, which can help maintain your kidney function better than other treatments.
* It can help relieve pain if something is blocking your kidney.
* It can treat urine infections more effectively than just medication.
* Compared to surgery, it has a lower risk of hurting your organs in your belly, causing less muscle injury and pain, and leaving a smaller scar.
* It doesn’t manipulate stones in your ureters (the tubes that carry urine from your kidneys to your bladder) as much. It can use a larger tube for better drainage than a J stent, which is a small tube inserted into your ureter.
* It’s particularly useful for severe kidney and urinary tract infections, as it usually helps reduce fever and relieve pain within a day or two.
