Percutaneous Nephrolithotomy
Percutaneous nephrolithotomy, or PCNL, is a procedure for removing medium-sized or larger renal calculi (kidney stones) from the patient's urinary tract by means of an nephroscope passed into the kidney through a track created in the patient's back. PCNL was first performed in Sweden in 1973 as a less invasive alternative to open surgery on the kidneys. The term "percutaneous" means that the procedure is done through the skin. Nephrolithotomy is a term formed from two Greek words that mean "kidney" and "removing stones by cutting."
Purpose
The purpose of PCNL is the removal of renal calculi in order to relieve pain, bleeding into or obstruction of the urinary tract, and/or urinary tract infections resulting from blockages.
During a percutaneous nephrolithotomy, the surgeon inserts a needle through the patient's back directly into the kidney (B). A nephroscope uses an ultrasonic or laser probe to break up large kidney stones (C). Pieces of the stones are suctioned out with the scope, and a nephrostomy tube drains the kidney of urine (D).
Standard PCNL
A standard percutaneous nephrolithotomy is performed under general anesthesia and usually takes about three to four hours to complete. After the patient has been anesthetized, the surgeon makes a small incision, about 0.5 in (1.3 cm) in length in the patient's back on the side overlying the affected kidney. The surgeon then creates a track from the skin surface into the kidney and enlarges the track using a series of Teflon dilators or bougies. A sheath is passed over the last dilator to hold the track open.After the track has been enlarged, the surgeon inserts a nephroscope, which is an instrument with a fiberoptic light source and two additional channels for viewing the inside of the kidney and irrigating (washing out) the area. The surgeon may use a device with a basket on the end to grasp and remove smaller kidney stones directly. Larger stones are broken up with an ultrasonic or electrohydraulic probe, or a holmium laser lithotriptor. The holmium laser has the advantage of being usable on all types of calculi.
A catheter is placed to drain the urinary system through the bladder and a nephrostomy tube is placed in the incision in the back to carry fluid from the kidney into a drainage bag. The catheter is removed after 24 hours. The nephrostomy tube is usually removed while the patient is still in the hospital but may be left in after the patient is discharged.
Mini-percutaneous nephrolithotomy
A newer form of PCNL is called mini-percutaneous nephrolithotomy (MPCNL) because it is performed with a miniaturized nephroscope. MPCNL has been found to be 99% effective in removing calculi between 0.4 and 1 in (1 and 2.5 cm) in size. Although it cannot be used for larger kidney stones, MPCNL has the advantage of fewer complications, a shorter operating time (about one and a half hours), and a shorter recovery time for the patient.Preparation
Most hospitals require patients to have the following tests before a PCNL: a complete physical examination; complete blood count; an electrocardiogram (ECG); a comprehensive set of metabolic tests; a urine test; and blood clotting test.
Aspirin and arthritis medications should be discontinued seven to 10 days before a PCNL because they thin the blood and affect clotting time.
Aftercare
A standard PCNL usually requires hospitalization for five to six days after the procedure. The urologist may order additional imaging studies to determine whether any fragments of stones are still present. These can be removed with a nephroscope if necessary. The nephrostomy tube is then removed and the incision covered with a bandage. The patient will be given instructions for changing the bandage at home.
The patient is given fluids intravenously for one to two days after surgery. Later, he or she is encouraged to drink large quantities of fluid in order to produce about 2 qt (1.2 l) of urine per day. Some blood in the urine is normal for several days after PCNL. Blood and urine samples may be taken for laboratory analysis of specific risk factors for calculus formation.
Risks
There are a number of risks associated with PCNL:
| • | Inability to make a large enough track to insert the nephroscope. In this case, the procedure will be converted to open kidney surgery. |
| • | Bleeding. Bleeding may result from injury to blood vessels within the kidney as well as from blood vessels in the area of the incision. |
| • | Infection. |
| • | Fever. Running a slight temperature (101.5°F; 38.5°C) is common for one or two days after the procedure. A high fever or a fever lasting longer than two days may indicate infection, however, and should be reported to the doctor at once. |
| • | Fluid accumulation in the area around the incision. This complication usually results from irrigation of the affected area of the kidney during the procedure. |
| • | Formation of an arteriovenous fistula. An arteriovenous fistula is a connection between an artery and a vein in which blood flows directly from the artery into the vein. |
| • | Need for retreatment. In general, PCNL has a higher success rate of stone removal than extracorporeal shock wave lithotripsy (ESWL), which is described below. PCNL is considered particularly effective for removing stones larger than 1 in (0.5 cm); staghorn calculi; and stones that have remained in the body longer than four weeks. Retreatment is occasionally necessary, however, in cases involving very large stones. |
| • | Injury to surrounding organs. In rare cases, PCNL has resulted in damage to the spleen, liver, lung, pancreas, or gallbladder. |
Normal results
PCNL has a high rate of success for stone removal, over 98% for stones that remain in the kidney and 88% for stones that pass into the ureter.Morbidity and mortality rates
Standard PCNL has a higher rate of complications than extracorporeal shock wave lithotripsy; however, it is more successful in removing calculi. The overall rate of complications following PCNL is reported as 5.6% in one recent study and 6.5% in a second article. About 20% of patients scheduled for PCNL require a blood transfusion during the procedure, with 2.8% needing treatment for bleeding after the procedure. The rate of fistula formation is about 2.5%.