Percutaneous Nephrolithotomy (PCNL)
A percutaneous nephrolithotomy (PCNL) is a surgical procedure aimed to remove medium-sized to large-sized kidney stones from the urinary tract. This procedure involves using a ‘Nephroscope’, which is guided to the kidney through an incision in the back.
This is an efficient minimally invasive surgical procedure used to remove kidney stones by cutting them into smaller pieces which can be efficiently flushed out of the body through the urine.
What is the purpose of a Percutaneous Nephrolithotomy (PCNL)?
The main goal of the PCNL procedure is to remove renal calculi (kidney stones) to alleviate pain and clear any obstruction in the urinary tract. Blockages in the urinary tract are known as UTI (urinary tract infection). Kidney stones may range in size from microscopic groups of crystals to as large as golf balls. Most of the times, the stones may pass uneventfully through the urine, and out of the body.
Kidney stones (renal calculi) develop through a process called as ‘Urolithiasis’. This makes the urine excessively saturated with mineral compounds found in the body. The overload of minerals in the urine may be the result of very acidic urine, low urinary output, or too much salt.
Kidney stones are formed from several different types of chemicals, which help to categorize them as:
Calcium oxalate calculi – A large majority of kidney stones are known to be of this type, which forms when calcium gets combined with oxalate (salt from oxalic acid). Certain foods, such as spinach and rhubarb are known to have high oxalic acid composition. The breaking of Vitamin C in the body also produces oxalic acid. Normally, the oxalic acid is secreted from the body in the urine. At times, it may get absorbed in large quantities in the body due to pancreatic diseases or a surgery of the small intestine.
Uric acid calculi – These types of kidney stones form from a highly acidic urine, by calcifying of uric acid crystals. These types of stones are seen in around 5% of all such cases. Certain kidney stones may often be a combination of uric acid crystals and calcium oxalate.
Cystine calculi – These are found in less than 2% of all cases of kidney stones. Cystine is an amino acid which is mostly found in proteins. Excessive secretion of this may result in formation of hexagonal-shaped crystals in the urine. A hereditary condition – Cystinuria – is the cause for this stone, which develops as the kidney is unable to absorb this amino acid again.
Struvite calculi – This is a hard crystalline form of magnesium aluminum phosphate. Kidney stones from this may result in UTI, caused by certain types of bacteria. These are also called as infection calculi as well.
Staghorn calculi – These types of kidney stones are large in size with distinct branches, made of struvite. These are often complicated to remove from the urinary tract.
How is the diagnosis for Percutaneous Nephrolithotomy (PCNL) done?
A routine abdominal x-ray may often show a kidney stone. Sometimes, smaller stones tend to pass out of the body through the urinary tract without any pain or discomfort (silent stones). In some cases, however, the kidney stones may require medical attention and surgical removal, due to their size, location and other such factors.
An intense pain in the lower back, on any one side, is usually a sign of kidney stone. The pain is felt due to the blockage of urine or as the movement of the stone through the urinary tract irritates the tissue. Groin and abdominal pain may be experienced in case the stone passes into the ureter – tube connecting kidney to bladder. Nausea and vomiting are also experienced as a result of this. Hematuria (blood in urine) is usually noticed, and the urination itself becomes a painful task. Frequent urination may also be seen.
In case the stone causes UTI, then the patient may also experience fever with chills.
Imaging tests and laboratory testing is used in combination to ascertain the size, location and type of the kidney stone (renal calculi), in order to determine the best-suited treatment for each. These also help to eliminate any other medical disorders that usually cause similar symptoms.
Imaging tests for diagnosing kidney stones (renal calculi)
Ultrasound and x-ray testing are normally advised to diagnose kidney stones. A standard x-ray may not be able to show pure uric acid calculi and cystine calculi. In such a case, the doctor may advise an IVP (intravenous Pyelogram). In this the doctor will first inject a contrast dye from the patient’s vein in one of the arms. This helps the x-ray image to clearly show the passage of urine within the entire urinary system.
Additionally, urine and blood samples are also required for laboratory analysis which can help to identify the presence of UTI. The kidney stone, when passed out from the patient’s body, is also sent to the laboratory for further analysis.
How to prepare for Percutaneous Nephrolithotomy (PCNL)?
Mostly, the patient will have to undergo some or all of the below tests before undergoing a PCNL procedure:
Complete blood count
Comprehensive metabolic tests
Blood thickness tests
The doctor will normally advise to refrain from taking aspirin and arthritis medication at least 10 days prior to the surgery date. This is to prevent the risk of blood thinning and eventually internal bleeding.
Laxatives may also be advised to ensure that constipation can be prevented during the recovery period.
Only clear liquids, such as water, fresh fruit juice and chicken/beef broth, are advised from at least 24 hours before the surgery. Orally, the patient is not allowed to intake anything at least from the midnight before the day of surgery.
What is aftercare like after a Percutaneous Nephrolithotomy (PCNL)?
A standard PCNL normally requires hospitalization for at least a week following the procedure. Additional imaging tests may be advised in this period to ensure all particles of the stones are removed.
If necessary, medium to large sized stones can be easily removed using a Nephroscope. After the procedure, the surgeon will remove the Nephrostomy tube and close the incision with a bandage. Instructions will be given on changing the bandage while at home to the patient.
Fluids are normally fed intravenously to the patient for a couple of days following the surgery. Later, the patient is encouraged to drink large quantities of fluid to ensure that they produce at least 2 quarts (1.2 L) of urine daily. Some blood in the urine is normal for several days after this surgery. Latest samples of urine and blood are also sent for analysis to a laboratory.
Are there any risks associated with a Percutaneous Nephrolithotomy (PCNL)?
There are several risks associated with PCNL, including:
Inability to make a sufficiently big track for Nephroscope. This will make the procedure a conventional open type surgery.
Bleeding may result from injury to blood vessels within the kidney and the incision.
Fever for 1 to 2 days.
Fluid accumulation in area around incision may result in infection too.
Intravenous fistula formation
Repeat procedure may be required for effective results.
Injury to surrounding organs or tissue.