Percutaneous nephrological technique is a technique for diagnosis and treatment of diseases of the renal pelvis, calyces and upper ureter through percutaneous pelvic access and is an important part of endoluminal urology.
1 History
In 1955, Goodwin performed percutaneous nephropuncture using a puncture needle to treat hydronephrosis, and in 1976, Fernstram performed successful percutaneous nephrolithotomy (PNL). In 1983, Whitfield performed the first percutaneous nephrolithotomy of the pelvic ureteral junction, which expanded the application of percutaneous nephrolithoscopy, and in the 1980s, with the popularization of ESWL and ureteroscopic techniques, percutaneous nephrolithoscopy was in a low ebb. In recent years, recognizing the damaging effect of ESWL on the kidney, percutaneous nephrostomy microfistula technique was established, and more effective lithotripsy methods such as laser and pneumatic ballistics emerged, and percutaneous nephrological techniques were newly developed.
Compared with ESWL and open surgery, the advantages of PNL are: stones can be found under direct vision and crushed and removed; stones can be crushed at one time and all of them can be removed at that time; the operation can be stopped and staged at any time; stones can be treated with ESWL; the damage is less than open surgery and less than repeated ESWL.
2 Indications
2.1 All kinds of renal and upper ureteral stones are indications for percutaneous nephrolithoscopy. The following are to be preferred for percutaneous nephrolithoscopy.
(1) Kidney stones larger than 2.5 cm, especially cast stones;
(2) Complex kidney stones, symptomatic diverticular stones, intrarenal pelvic stones with joint stenosis, etc;
(3) cystine stones, calcium oxalate monohydrate stones that ESWL is ineffective.
2.2 Ureteral stenosis in the upper part of the ureter or the connecting part.
2.3 Removal of foreign bodies from the renal pelvis and upper ureter.
3 Instruments
3.1 Puncture guidance equipment: ultrasound and X-ray fluoroscopy machine. Ultrasound-guided puncture is safe and accurate. x-ray fluoroscopy is necessary.
3.2 Puncture instruments: including puncture needle, guidewire, dilator, and operating sheath. The guidewire is usually a super-slip guidewire. The dilator is a group of plastic or metal instruments in 2F increments. teflon operating sheath has a certain toughness, which can keep the sinus tract, and can be properly deformed, with little damage to the kidney, and also facilitates the removal of stones.
3.3 Nephroscopy: there are hard and soft, ureteroscopy can be used for microstomy percutaneous nephroscopy.
Auxiliary instruments: stone extraction forceps, stone basket, ureteral catheter, D-J tube, nephrostomy tube, ureter, etc;
3.4 Lithotripsy equipment: pneumatic ballistic lithotripsy, ultrasound lithotripsy, laser lithotripsy, etc;
3.5 Pressure perfusion pump: to maintain a clear field of view and flush out lithotripsy;
3.6 Other instruments and supplies: scalpel, suture, needle holder, infusion film, etc;
3.7 Auxiliary drugs: antibiotics, hemostatic agents, isoprostanes, dexamethasone, etc;
3.8 Perfusion fluid: generally saline, heated to 37°C.
4 Staging of percutaneous nephrolithotomy
4.1 Stage I surgery: nephrostomy and lithotripsy are performed at the same time. Most PNL can be performed in stage I surgery. Advantages: one operation, one anesthesia, less pain, shorter hospital stay, lower cost. Disadvantages: easy to bleed, poor visualization, and easy to fail after the operation sheath is dislodged.
4.2 Stage II surgery: Pre-emptive nephrostomy, after a period of sinus tract formation and physical condition improvement, then surgery. It is suitable for those with combined infection and post-renal renal insufficiency; those with bleeding tendency; those with severe bleeding in stage I operation; and those with residual stones after stage I or open surgery. Advantages: sinus tract has been formed, less bleeding and clear vision. For those who pre-decide to perform stage II, local anesthetic puncture fistula can be performed under ultrasound guidance. Cast stones without hydronephrosis have a higher failure rate for ultrasound-guided puncture placement. Stage II surgery can be performed without anesthesia.
5 Preoperative preparation
5.1 Clear diagnosis: intravenous urography to understand the structure of the renal pelvis and calyces and to select the most suitable puncture calyces. If the affected side is not clearly visible, retrograde contrast or water imaging should be performed.
5.2 Exclude contraindications: those whose systemic function cannot tolerate the procedure and those with bleeding tendency should be controlled and stabilized.
5.3 Treatment of urinary tract infection: for those with preoperative abnormal urine routine and fever, use sensitive antibiotics. For suspected renal pus accumulation, puncture and drainage first, and control after phase II surgery.
6 Anesthesia, body position, intraoperative medication
6.1 Anesthesia: simple nephrostomy can be completed under local anesthesia. phase I PNL, using even epidural anesthesia, can ensure a long operation and facilitate patients to hold their breath to cooperate with the operation. The patient’s position changes greatly during percutaneous nephrolithoscopy, and the lumbar anesthesia level is unstable, in addition, lumbar anesthesia has a large impact on blood pressure;
6.2 Position: After anesthesia, the patient is placed in a lithotomy position, and the F5-7 ureteral catheter and urinary catheter are left in place. The role of the ureteral catheter is: (1) water injection to increase the pressure in the renal pelvis, facilitating successful renal puncture; appropriate injection of contrast agent can make the target calyces visible and guide the direction of the puncture needle. (2) it can be used as a marker to identify the ureter of the renal pelvis; (3) to prevent lithotripsy from entering the ureter during lithotripsy; and (4) to facilitate the discharge of lithotripsy from the operating sheath by pressurizing water injection through the catheter. Renal puncture and operating position: use prone position, put the abdomen up.
6.3 Intraoperative medication: prophylactic antibiotics were administered. Give 1 to 2 kU of lithotripsy to reduce intraoperative bleeding. Give isoproterenol 25mg and dexamethasone 5mg to treat the patient’s chills.
7 Operation method
The key to PNL is to establish and maintain a reasonable percutaneous nephrostomy access. Microscopic identification of the direction of the renal pelvis, calyces, and ureter is also very important for finding stones. Then, effective lithotripsy methods for stone extraction should be mastered.
7.1 Selection of the target renal calyces: The selection of the punctured renal calyces should be formulated according to the specific situation of the stone and the renal pelvis and calyces. Principle: It is best to select the posterior group of the lower renal calyces. After the puncture of the lower calyces, stones in the lower calyces, renal pelvis, and middle and upper calyces can be treated; after the puncture of the middle calyces, stones and PUJ stenosis in the middle calyces, renal pelvis, upper and lower calyces, and upper ureter can be treated. The path of puncture is from the lateral margin of the kidney in a posterior position into the renal parenchyma and along the axis of the calyces into the calyces. Avoid direct puncture of the renal pelvis without passing through the sinus tract of the renal parenchyma, which is prone to extravasation of perfusate, resulting in displacement of the kidney, alteration of the fistula tract, and operational failure. Postoperatively, urinary cysts are easily formed.
7.2 Puncture procedure: The skin puncture point is usually chosen to be 10-12 cm from the paraspinal opening, 12 under or 11 between the ribs after the posterior axillary line. The puncture site and direction are first determined under fluoroscopy/B ultrasound. A small incision is made in the skin at the puncture site. After the puncture needle enters the renal peritoneum, it moves up and down with respiration, at which point it is advanced another 1.5 to 2 cm to enter the renal calyces with urine overflow. The guidewire is sent through the puncture needle into the renal calyces, renal pelvis, and ureter. The soft part of the front end of the guidewire should enter the renal pelvis completely. Otherwise, the dilator cannot be properly guided into the renal calyces. The dilator is used to dilate along the guidewire step by step to the desired ductal diameter. The direction of the dilator should be the same as the direction of entry of the puncture needle. The depth of dilator entry should not exceed the depth of puncture needle entry. After dilatation, the operating sheath is placed into the renal calyces.
7.3 Lithotripsy method: Generally, the stone is fragmented along the edge of the stone, so that it can be easily broken into pieces and flushed out with the perfusion fluid. After fragmenting the pelvic portion of the cast stone, the stone can be moved into the pelvis by flicking the stone along the edge of the calyx.
7.4 Stone extraction method: small crushed stones flow out with the flushing fluid, and larger crushed stones are clamped out with foreign body forceps.
8 Postoperative treatment
8.1 General treatment
At the end of the operation, a D-J tube was placed in line through the fistula and a nephrostomy tube was left in place. If there is more intraoperative bleeding, the fistula tube is clamped to facilitate hemostasis. Postoperative bed rest, attention to the presence of excessive blood loss or water absorption, timely management and application of antibiotics.
8.2 Treatment of residual stones
(1) Residual stones that can be taken through the sinus tract should be removed in 5-7 days after phase II;
(2) For small stones that cannot be easily retrieved through the sinus tract, perform ESWL;
(3) For large residual stones that cannot be easily retrieved through the sinus tract, a second channel can be punctured for lithotripsy;
(4) residual cystine and uric acid stones, lithotripsy through the fistula.
8.3 Treatment of the fistula
If the fistula is dislodged within 1 week, it is difficult to put back and should be retubated.
The fistula can be removed if the patient has no fever, back pain, or urinary extravasation. The fistula is maintained for 3 to 4 days after stage I surgery to achieve hemostasis.
9 Complications and their management
9.1 Bleeding: It is a common comorbidity of stage I percutaneous nephrolithoscopy. Intraoperative renal parenchymal bleeding can be controlled by operating sheath compression. If intraoperative bleeding is severe, the procedure should be stopped and compressed with a balloon catheter. More hemorrhage requires blood transfusion, poor bleeding control, action vein angiography, selective renal artery embolization if necessary, or even open surgical exploration.
9.2 Renal pelvis perforation: too much movement of the instrument is easily caused, and contrast can be injected to clarify. Renal pelvis perforation is found to immediately stop the operation, place ureteral stent tube and nephrostomy tube, drain adequately, and treat the stone in phase II.
9.3 Dilutional hyponatremia: caused by excessive water absorption. Stop the operation, check electrolytes urgently, and give hypertonic salt, diuresis, and oxygen.
9.4 Perirenal pus accumulation: focus on prevention. Pre-operative preparation should be adequate, and post-operative ureteral catheter and nephrostomy tube should be kept unobstructed.
9.5 Proximity organ injury: 11 intercostal puncture may damage the pleura, which can be avoided by using ultrasound-guided puncture. Once a patient is found to have a pneumothorax, immediately stop the operation and treat according to the principles of pneumothorax management. Injury to the intestinal canal, conservative treatment is often effective.