1. History of Development
Percutaneous nephrolithotomy (PCNL) was developed on the basis of percutaneous nephrostomy. 1955 Goodwin was the first to report the success of percutaneous nephrostomy in relieving obstructive hydronephrosis by using the Trocar technique. Pederson was the first to use X-ray fluoroscopic guidance and ultrasound guidance for puncture respectively, which improved the accuracy and safety of puncture and tube placement.
In 1976, Fernström and Johansson reported four cases of successful X-ray fluoroscopic lithotripsy through the channel established by percutaneous nephrostomy, which they considered to be suitable only for stones less than 1.5 cm. The indications of percutaneous nephrolithoscopy for the treatment of kidney stones were expanded from stones less than 1.5 cm to larger stones, and the lithotripsy effect became better and better, thus making percutaneous nephrolithoscopy widely used in the treatment of kidney stones and upper ureteral stones. In China, the application of fiberoptic cholangioscopy for percutaneous nephrostomy stone extraction was successful in 1982, and percutaneous nephrolithotomy was carried out in 1984.
In the 1980s, with the popularization of Extracorporeal Shock Wave Lithotripsy (ESWL) and Ureteroscopy, percutaneous nephrolithotomy for urinary stones was once in a low ebb. However, ESWL has a damaging effect on the kidney when treating larger stones and even causes loss of kidney function, which makes people realize the need of PCNL again. In recent years, with the improvement of lumpectomy equipment and internal lithotripsy equipment, PCNL has been gradually promoted again.
2.2 Indications and Contraindications
2.2.1 Indications
①Large stones and antler-shaped stones.
②Lower calyx stones, due to the body position and small calyx expansion, it is sometimes difficult to discharge the fragmented stones after ESWL.
(③) The simultaneous presence of distal urethral obstruction of stones, such as small cervical diverticulum, congenital and open postoperative pelvic-ureteral junction stenosis, makes it difficult to expect smooth expulsion of lithotripsy after ESWL. When PCNL is performed, the stenosis can be dilated at the same time and a stent tube or endoluminal pyelotomy can be placed to help prevent stone recurrence and stone expulsion.
If other treatments fail, especially ESWL, in vivo lithotripsy can break the stone.
⑤ In obese patients, if the distance from the skin to the stone exceeds the distance from the second focal point of the extracorporeal shock wave lithotripter to the edge of the reflector, the stone cannot be broken, and percutaneous nephrolithotomy can be considered first.
2.2.2 Contraindications
① Systemic hemorrhagic disease.
②Acute infection or renal tuberculosis.
③Severe kyphoscopic deformity and severe cardiopulmonary insufficiency resulting in inability to lie prone.
④High-grade kidney with hepatomegaly or splenomegaly.
⑤Small intrarenal type or branching type renal pelvis.
(6) Ischemic heart disorders.
(7) Uncorrected diabetes mellitus.
(viii) Those who have a cardiac pacemaker and require intraoperative fluid electrolysis.
2.3 Equipment and instruments
2.3.1 Puncture guidance device The percutaneous renal puncture guidance device can be either ultrasound or X-ray fluoroscopy. X-ray fluoroscopy is preferable with C-arm fluoroscopy. The ultrasound guidance device can be a line array or real-time imager, preferably with a dedicated puncture probe, but a common probe with an additional puncture guide device is also available. Ultrasound guidance can show the main structure of the kidney at the puncture site, which can accurately grasp the depth and direction of the puncture, and has a high success rate of puncture.
Since percutaneous nephrolithotomy usually requires a very thick expansion of the puncture channel (generally expanded to 24F, but a smaller 14F-18F channel can be used if microstomy percutaneous ureterorenoscopy is used to retrieve the stone), and ultrasound-guided devices cannot be used like the injection of contrast agent under X-ray fluoroscopy to visualize the collection system and facilitate accurate expansion of the dermal kidney channel by dilators, percutaneous nephrolithotomy is generally used for X-ray fluoroscopy Therefore, percutaneous nephrolithotomy is usually performed with X-ray fluoroscopic guidance or in combination with ultrasound guidance.
2.3.2 Fistula instruments Instruments include puncture needles, guidewires and dilators.
2.3.3 Nephroscope This is a necessary instrument for PCNL. The nephroscope currently used is mainly rigid nephroscope, which consists of 3 parts: body, sheath and obturator. In addition to the optical lens structure, there is also a 12F operating center orifice, which can be used for continuous irrigation and also for passing through the lithotripsy basket, lithotripter and various lithotripsy probes, etc. The sheath is also made of metal and is about 20-22 cm long. The sheath is also made of metal, with specifications ranging from 16.5F to 26F, and the distal end of the obturator is conical, with a hollow center that allows the passage of a 0.089-0.097 cm diameter guidewire.
There are two types of rigid nephroscopes.
① Right-angle nephroscope The angle of view of a right-angle nephroscope is generally 0° to 5°. The eyepiece and objective lens of this nephroscope are not in the same line, so that the lithotripter, lithotripter basket and lithotripter probe can be operated under direct vision. After the instruments are inserted, the amount of irrigation solution is still 500ml~600ml per minute, so that the intraoperative field of view can always be in a clearer state, which is conducive to the operation of the instruments.
There are two types of paracentesis nephroscopes, one with a sheath, which is basically similar to the right-angle nephroscope except that the endoscope is equipped with a lateral arm observation system at a 30° angle, and the other without a sheath, which is composed of an optical conduction system, irrigation and instrument operation center groove and an ovoid shell to form a complete working part. Due to its ovoid cross-section, the gap between the nephroscope and the working sheath is increased, allowing larger stone fragments to be flushed out through this gap.
2.3.4 Lithotripsy instruments The direct endoscopic removal of stones is the simplest, most effective and least invasive method for percutaneous nephrolithoscopy and is the most commonly used method for percutaneous nephrolithoscopy. There are two types of lithotripsy instruments: rigid and bendable. Commonly used lithotripsy instruments: ① various lithotripsy baskets, such as three-wire, four-wire, six-wire flush-tailed lithotripsy baskets, linear-tip lithotripsy baskets, etc.; ② various lithotripsy forceps, such as bendable retractable triple radiation stone gripper or gripping forceps, rigid retractable triple radiation stone gripper or gripping forceps, rigid alligator forceps, rigid lithotripsy forceps, etc.
2.3.5 Lithotripsy devices Commonly used lithotripsy devices include pneumatic ballistic lithotripter, laser lithotripter, electrohydraulic lithotripter, combined pneumatic ballistic/ultrasound lithotripter, etc.
2.4 Complications
Although PCNL is a minimally invasive procedure, there are still certain mortality and complications if it is not well mastered. The postoperative mortality rate is about 1.0% to 2.0%, which is mainly due to the continuous occurrence of complications. Complication rate due to the different criteria and experience of each person on the inclusion of complications, can be from 4% to 40%, or even up to 70%, some people even PCNL in the once blood transfusion or postoperative temperature of 38 ℃ or more are included in the complications, but the incidence of serious complications (such as intraoperative haemorrhage, delayed bleeding, sepsis, adjacent organ damage, etc.) is less than 5% to 6%, complications can occur in the puncture, expansion, the nephrostomy tube insertion, retention, and removal, as well as any of the processes of stone extraction and lithotripsy.