Percutaneous nephrolithotomy (PCNL) is a minimally invasive procedure for the removal of kidney stones. Today, kidney stones are treated using extracorporeal shock wave lithotripsy (ESWL), ureterorenoscopy (URS) or percutaneous nephrolithotomy (PCNL). Open surgical procedures are only used in special cases.
Below you will find further information and specialists.
PCNL therapy is a minimally invasive form of treatment similar to ESWL and (flexible) renal and ureteroscopy (ureterorenoscopy).
ESWL breaks up kidney stones using shock waves. The patient then removes these via the urinary tract. This procedure is the method of choice for most kidney stones.
Indications for PCNL arise where ESWL reaches its limits.
It is suitable for patients:
The following factors play a role here:
A kidney stone in size comparison @ New Africa /AdobeStock
Percutaneous nephrolithotomy is not suitable in the case of
Percutaneous nephrolithotomy is usually performed under general anesthesia with the patient lying on their stomach. However, it is also possible in an oblique supine position.
Before PCNL, the retrograde insertion of a balloon ureteral catheter is useful. Doctors inject a contrast agent through this to expand the renal pelvic caliceal system and make it visible, which simplifies the kidney puncture.
Contrast agent visualization of the renal pelvic caliceal system via a balloon ureter catheter blocked in the renal pelvis
The puncture itself is performed using a puncture aid that is rigidly connected to the ultrasound probe. This serves as a guide for the puncture needle.
Access to the hollow system of the kidney is usually via the lower calyx group. This puncture is the least risky. The lower pole of the kidney has the lowest density of blood vessels, so the risk of bleeding is lowest here.
When puncturing the middle or upper calyx of the kidney, on the other hand, it is easier to injure neighboring organs.
If doctors cannot reach the stone-bearing calyx, they can alternatively puncture another calyx group or a calyx diverticulum.
Doctors use a puncture needle to insert a guide wire into the renal hollow system, which they use to widen (bougie) the puncture channel.
There are various options for widening a narrow area to a diameter of 6 to 10 millimetres:
Doctors insert the working shaft into the widened channel. This allows safe access to the renal pelvic caliceal system. The surgeon can then inspect the hollow system under continuous irrigation.
Various lithotripsy probes are available to break up the stone. In addition to ultrasonic drilling probes with continuous suction, pneumatic or laser-based probes are primarily used today.
Ultrasonic drilling probes are suitable for rigid nephroscopes . The reason for this is the rapid comminution and simultaneous suction of large stone masses.
Holmium:YAG laser lithotripsy is mainly used for flexible nephroscopes or the mini PCNL.
The holmium:YAG (holmium:yttrium-aluminum-garnet) laser is suitable for fragmenting all stone compositions. Doctors then remove any remaining fragments using forceps or baskets.
At the end of the PCNL, endoscopic and radiological checks are carried out to ensure that there are no stones. If there are no stones, a second-look PCNL, ESWL or URS is required as a second procedure.
In the case of large stone masses, primary planning of a combination treatment with PCNL and flexible URS is also possible.
After the operation, doctors usually insert a balloon nephrostomy via the access channel. This enables safe urine drainage and hemostasis by compressing the puncture tract.
In addition to the flexible nephroscopes, there is another technical innovation, the mini PCNL. These instruments are designed to allow access to the renal hollow system with less damage to the tissue.
Mini-PCNL is less of an alternative to PCNL, but rather an alternative to ESWL. This is suitable for the treatment of subcaliceal concretions.
The success rate of percutaneous stone removal depends on
In general, PCNLs achieve stone clearance rates of > 90 %.
Physicians prefer to use PCNL for calculi in the lower calyx group. A study by the Lower Pole Study Group shows the following results for lower calyx stones with an average size of 14 mm:
Further studies show that percutaneous stone removal is also possible with good results in the following diseases:
ESWL achieves excellent results in children and is used in most cases. However, PCNL is preferable in the following cases:
Mini nephroscopes should be used for patients who are not fully grown. The success rate here is up to 100 % stone-free.
The most common complications during PCNL are venous bleeding. These usually show no symptoms, but can lead to the procedure being aborted due to impaired visibility.
The majority of postoperative complications after PCNL, such as prolonged bleeding, urinary tract infections or fever, can be treated conservatively.
If severe venous bleeding occurs that does not stop spontaneously, doctors clamp the nephrostomy. If this does not stop the bleeding either, there is usually arterial bleeding. Doctors can close this after appropriate diagnosis.
Open surgery is therefore rarely necessary. Large studies have shown that only 10-15% of bleeding requires transfusion.
Injuries to neighboring organs such as the intestines, spleen, liver or lungs occur rarely, but are particularly serious. The puncture of an upper renal calyx via an access route above the ribs is particularly risky. This can result in injury to the chest organs.
In our opinion, puncture under combined ultrasound- and fluoroscopy-guided control is a decisive measure to reduce such complications.
By using sonography for fluoroscopy, doctors can identify and spare neighboring organs such as the intestine, liver, spleen and lungs .
We therefore take a critical view of radiologically guided kidney puncture, which is particularly widespread in North America .
The entire procedure (preoperative sonography, procedure planning, puncture, stone removal, postoperative monitoring) should remain in the hands of the urologist.
The puncture of the kidney is the most sensitive part of the procedure. The success of the operation depends on it. The surgeon should therefore perform this procedure himself, as he can assess the optimal access route.
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