Percutaneous Nephrolithotomy (PNL)
This surgical approach is preferred for very large kidney stones (generally 2 cm or more in size) or for those that have not been treated effectively with either SWL or ureteroscopy. PNL is performed by creating a small, direct channel into the kidney through the back. This channel is initially established by an interventional radiologist who works with your surgeon. Once the channel is established, you are then taken to the operating room where your surgeon will enlarge, or dilate, the passage and then begin treating the stone.
While more invasive than SWL or ureteroscopy, the channel's final diameter is just over a centimeter wide and is minimal in size compared to the open incisions that were necessary in the past. Because you will need to be in a prone (face down) position during surgery, general anesthesia is required. Your surgeon treats the stone by inserting large probes directly into the kidney in order to effectively fragment the stone and also suction out the pieces. Large fragments also can be removed with forceps. As a result, the PNL approach provides the highest chance to completely clear the kidney of all stones in a single setting, thus minimizing the need for additional surgical procedures.
Before the procedure:
You will undergo a complete examination in the office, and blood tests will be obtained to ensure that there are no abnormalities prior to surgery. Your surgeon will also order x-ray studies to look carefully at the inner anatomy of the kidney. This allows your surgeon to coordinate the planning for the channel's optimal location with the interventional radiologist. In cases where the stone is extremely large, more than one channel may need to be created.
Risks of the procedure:
Because a passage is made directly into the kidney, a transfusion may be needed in 5 to 8% of cases. If the stone is located toward the top of the kidney, injury to the covering of the lung (pleura) can occur, which occasionally requires placement of a tube into the chest cavity to allow this area to heal after the procedure.
Contraindications to the procedure:
PNL cannot be performed in patients with significant bleeding problems. In addition, those patients on blood thinners must stop taking them for a few days before and after the procedure to minimize the risk of bleeding. Your surgeon will work with your primary doctor or cardiology to determine the safest time period over which the blood thinner can be stopped. Some patients may also have anatomy issues that make it impossible to create a passage into the kidney without injury to adjacent structures such as the intestine or lung. In these cases, alternative approaches will be recommended. Active urinary tract infections must be treated appropriately before PNL can be performed. Selected patients may be able to be treated without external drainage tube.
After the operation:
A drainage tube may be placed across the channel into the kidney after the procedure. In most cases, patients can go home the afternoon following the surgery. While you are in the hospital, your surgeon may order x-rays or a CAT scan to be done the morning after the procedure to ensure that all stones have been removed from the kidney. Typically, a dressing or drainage bag will be placed over the incision for a few days to prevent leakage of urine as the incision heals. You will initially be seen within a week or two after leaving the hospital to check on your progress. Other follow-up appointments will be arranged as needed to ensure that your recovery is progressing as expected.