What is Percutaneous Nephrolithotomy (PCNL)?
Percutaneous nephrolithotomy (per ~ through, cutaneous ~ skin, nephro ~ kidney, lithotomy – surgical removal of stone) is a surgical procedure for the removal of kidney stone(s) lodged in the renal pelvis of the kidney. PCNL is often referred to as ‘keyhole’ surgery because an access track is created through the skin into the kidney without the need for a large open incision.
Endoscopic instruments can be inserted through this track for kidney stone destruction or removal. PCNL is a minimally invasive procedure which allows for shorter hospital stays, quicker recovery time and minimal scarring compared to open surgery.
Indications for PCNL
When to do a percutaneous nephrolithotomy for kidney stone removal?
The convenience and safety of other procedures like extracorporeal shockwave lithotripsy (ESWL) makes it the preferred option for kidney stone destruction.
At times, an ESWL may not be viable (refer to ESWL Contraindications) or is unsuccessful in fragmenting the stone, or the fragmented stone(s) may not pass out of the urinary system. In these instances, percutaneous nephrolithomy is indicated. With modern imaging techniques and pre-operative testing, the urologist can decide on which procedure would be more successful with minimal risk of complications.
Other indications for a PCNL would include :
- Kidney stones larger than 2cm (20mm stone). Sometimes an ESWL is still considered for large stones up to 3cm (30mm) which are soft, like calcium oxalate stones.
- Hard stones like cystine kidney stones.
- Stones causing an obstruction of the ureteropelvic junction (kidney-ureter).
- Stone located towards the lower pole of the kidney.
- Severe infection.
In certain emergency cases where the stone is causing complete obstruction or there is the risk of a severe infection spreading to other parts of the body, a percutaneous nephrostomy may be done to allow for the drainage of urine, blood and infected material. Kidney stone removal may be conducted once the patient is stabilized.
Percutaneous nephrolithotomy (PCNL) is conducted under general anesthesia (GA) and a 1 to 2 day hospitalization is usually necessary.
- The patient will have to lie in the prone position (lying face down) on the fluoroscopy table. Fluoroscopy allows the surgeon to identify the exact location of the kidney by providing real time fluoroscopic images. It requires the use of contract dye which is administered via the blood (intravenous) or into the urinary tract (retrograde).
- The approach for the optimum access tract will be identified and should avoid surrounding abdominal organs.
- A needle is passed through the skin of the flank (between the last rib and iliac crest of the pelvis) and into the renal calyx. At times, entry is slight above the last rib although this may not be viable if drainage via a nephrostomy tube is to be considered.
- A guide wire is then passed through the needle and this allows for dilators to be used to enlarge the tract.
- A nephroscope is then inserted to allow the surgeon to visualize the area.
- Smaller stones may be grasped with a forceps and basket and removed without any need for fragmentation. Larger stones will have to be fragmented – ultrasonic, pneumatic or laser lithotripsy (‘stone crushing’).
- Stones and fragments are removed and a nephrostomy tube is inserted to allow for drainage over the next 24 to 48 hours. Sometimes a nephrostomy tube is not inserted (tubeless percutaneous nephrolithotomy) but this is not common.
- The entire procedure takes about 1 to 2 hours until all the stone fragments are removed or if bleeding obstructs the surgeon’s view.