Over the past 25 years, with the development of extracorporeal shock wave lithotripsy (ESWL), ureteroscopy (URS), percutaneous nephrolithotomy (PCNL) and laparoscopy, and the maturation of intracavitary lithotripsy techniques, the proportion of patients treated with open surgery has decreased significantly. In the literature, only about 1% to 5.4% of stone patients are currently treated with open surgery, and in 2000, only about 2% of stone patients in the United States were treated with open surgery.
Minimally invasive surgery with its advantages of less trauma, fewer complications, faster postoperative recovery and shorter hospital stay has become the main direction of urology development, especially in recent years with the emergence of intracavitary lithotripsy means such as pneumatic ballast, laser, ultrasound and the continuous progress of minimally invasive technology, especially the maturation of percutaneous nephrolithotomy (PCNL) technology, through cystoscopy, ureteroscopy, percutaneous nephrolithoscopy and other intracavitary technology combined with the latest The minimally invasive treatment of urinary stones through cystoscopy, ureteroscopy and percutaneous nephrolithoscopy combined with the latest pneumatic ballistics, laser and ultrasound lithotripsy has made a breakthrough, and almost all urinary stones can be treated by minimally invasive intracavitary means, which has completely changed the treatment mode of traditional urinary stones.
1.ESWL
Since Chaussy started to report the successful treatment of the first kidney stone patient with ESWL in 1980, ESWL has started a new era in the treatment of urinary stones, and relatively non-invasive ESWL has become the preferred treatment for most kidney stones and ureteral stones.
1) ESWL lithotripsy principle and third generation lithotripter
Shock wave is an explosive pressure pulse of high energy amplitude produced in a very short period of time by a sudden release of energy in a medium such as air or water. Shock waves are generated in the same medium, propagate in a straight line, and have little attenuation in media of similar density (such as water and soft tissue).
However, when the shock wave encounters the interface of two substances with different acoustic impedances (e.g., the density of stones and water are very different), the energy is released sharply, generating a large tensile internal stress inside the stone, and after repeated impacts, the tensile strength of the stone cannot resist this tensile internal stress, and the stone is fractured.
When the shock wave penetrates the stone, the direction of the interface changes, i.e., deflection and refraction, and this interface difference forms a certain torsion and shear force, resulting in the stone surface layer by layer, until the stone diameter is less than 2 mm, so that the stone can be discharged naturally.
Many recent technical enhancements and improvements to the shock wave lithotripter have greatly expanded its clinical applications. The third generation lithotripter, with its high quality image positioning system, high lithotripsy efficiency, and low human injury, combines many of the features of an “ideal lithotripter”, including dual imaging and a variety of different shock wave powers, dual imaging with both X-ray fluoroscopy and ultrasound positioning, and X-ray fluoroscopy positioning to effectively X-ray fluoroscopy can effectively determine the location of urinary tract stones.
The advantage of ultrasound localization is that it is non-radioactive, monitors the location of stones in real time and effectively shows negative stones that can be penetrated by X-rays, and can effectively locate stone fragments of 2-3 mm in diameter, which is superior to conventional KUB plain films when evaluating residual stones after lithotripsy. The treatment can be started with X-ray fluoroscopy to locate stones and then switched to ultrasound for real-time monitoring of the lithotripsy process, which significantly improves the efficiency of lithotripsy and minimizes the number of X-ray exposures. The multiple options of different power adjustments allow the urologist to choose the intensity of the bombardment energy according to the hardness of the stone, the degree of fragment formation and the patient’s tolerance to the treatment.
2) Be alert to the complications of ESWL treatment and apply ESWL appropriately
ESWL as an ideal and relatively non-invasive lithotripsy method is suitable for the treatment of most urinary stones. With the passage of time and deepening knowledge of shock waves, studies have confirmed that no matter which shock wave source is applied, shock wave lithotripsy can also cause certain damage to the renal parenchyma, especially to the tiny blood vessels of the kidney, and this damage may be irreversible, and multiple lithotripsy of the same part of the kidney in a short period of time This damage may be irreversible, and multiple lithotripsy of the same part of the kidney in a short period of time can even cause loss of function of the affected kidney.
The complications of ESWL have attracted attention, including kidney injury, subepithelial hematoma, secondary hypertension, stone street formation, and renal atrophy, etc. Cases of renal atrophy and renal failure after ESWL have been reported in China. The shock wave also has a damaging effect on kidney tissue, and the interval between two ESWL treatments should be greater than one week. The damage to the kidney tissue can be completely repaired with less than three treatments, but the more the number of treatments, the greater the damage to the kidney tissue. Therefore, it is better to keep the total number of treatments below three.
In 1997, Collado Serra et al. observed 10,953 cases of 21,699 ESWL from 1987 to 1996, with 31 cases of renal hematoma, an incidence of 0.28%, and 24 cases of low back pain and 11 cases of perirenal hematoma. The cases had low back pain and hypertension occurred in 11 cases. In contrast, Gallego Sanchez et al. found 7 cases (1.02%) of clinical renal hematoma in 686 cases with 1,313 ESWLs.
There is consensus in minimizing comorbidities. The second ESWL should be performed preferably after 10 days; the number of shocks should not be too many, and should be limited to 2,500; patients with combined urinary tract infection should be controlled before ESWL, etc. The damage to the renal parenchyma and complications of ESWL should be minimized. Only by reasonably choosing different treatment plans and lithotripsy means according to the specific conditions of patients can we get good treatment results.
3) Management of complications of ESWL
Common comorbidities of ESWL.
(1) Minor hematuria usually does not need to be treated.
(2) Renal colic requires symptomatic management.
(3) The formation of “stone street”, if the broken stones accumulate in the ureter and form “stone street”, sometimes it will cause infection and fever, which need to be removed by ureteroscopy or ESWL in time, generally the larger kidney stones can be left in the affected ureter before ESWL. Stenting tube. If the “stone street” obstruction is long or the secondary infection is serious, a nephrostomy is needed to drain the urine, relieve the symptoms and protect the kidney function, and then remove the fistula after the stone is drained.
(4) Organ injury, skin bruising (skin injury), hematuria (kidney injury), fecal occult blood (intestinal injury), subperitoneal hematoma, etc. may occur after lithotripsy, and in severe cases, the kidney will be shattered and life threatening. Depending on the specific circumstances of the injury, timely treatment is required.
4) Clinically insignificant residual stone fragments (CIRF) after ESWL
Most of the clinical renal and ureteral stones less than 2 cm in diameter can be treated by extracorporeal shock wave lithotripsy. In contrast to intracavitary and open surgery, patients cannot immediately remove all stone fragments, and residual stone fragments often accumulate in the infrarenal calyces, mostly in patients with a funnel pelvic angle less than 90 degrees. Incomplete stone fragments, residual stone fragments, stone streets and obstruction are common problems encountered by urologists after stone treatment with ESWL.
Residual stone fragments less than 5 mm in diameter are usually spontaneously expelled after ESWL and are called “clinically insignificant residual stone fragments” (CIRF), but CIRF can also cause ureteral obstruction and is an important risk factor for stone recurrence and further increase in stone size. The results of meta-analysis show that CIRF cannot be determined only by the size of stone fragments, but also by the morphological state of the ureter. Therefore, patients with stones with CIRF after ESWL need to be followed up closely for timely adjuvant therapy.
About 21% to 59% of ESWL-treated patients have stone fragments less than 4 mm, and Streem et al. found a 43% risk of symptomatic attacks or need for adjuvant therapy after a mean of 26 months of treatment in patients with stone fragments less than or equal to 4 mm at follow-up. The rate of stone clearance decreased as the residual stone fragments remained inside the kidney for longer periods of time, but the location of the residual stone fragments had no significant effect on the rate of stone clearance.
The overall incidence of stone streets in patients who have had ESWL is 1-4%, increasing to 5-10% in patients with large stones (>2 cm2) and 40% in patients with partial or complete deerstalker stones.
CIRF is the main cause of ureteral stone street, and to prevent possible complications from stone fragments, large renal stones are treated without ESWL as much as possible, using “sandwich” therapy (ESWL before PCNL and adjunctive ESWL after PCNL). Reduce complications caused by residual stone fragments, especially when treating large stones.
More importantly, to alleviate the complications caused by stone residual fragments, ESWL has to be made more effective. The effectiveness and safety of ESWL can be improved by reducing the number, frequency, and energy of shock waves, using two shock wave tubes simultaneously, and firing shock waves at carefully calculated intervals. heimbach et al. demonstrated in vitro model experiments that shock wave lithotripsy followed by chemical lysis therapy can improve the efficiency of stone crushing.
2. Minimally invasive endoluminal treatment of urinary calculi
ESWL, as an ideal and relatively noninvasive lithotripsy method, is suitable for the vast majority of urinary stone treatment, but it cannot completely replace other treatment methods. In addition, the possible complications caused by ESWL are receiving increasing attention, and for kidney stones larger than 2 cm in diameter, multiple stones and large volume of complex kidney stones (complete and partial deerstalker stones), ESWL treatment is difficult ( It often requires repeated and multiple lithotripsy), with many complications and a large number of stone fragments easily accumulate in the ureter after lithotripsy causing acute obstruction.
Nowadays, with the miniaturization of endoluminal lithotripsy instruments, laser and ultrasound as percutaneous nephrolithotomy and ureteroscopy-assisted lithotripsy, the vast majority of urinary tract stones can be treated by endoluminal minimally invasive methods. Currently, the application of holmium laser fiber with a diameter of 200 μm has been reported to lithotripsy in a retrograde manner through ureteroscopy for stones in almost any location within the renal collecting system, in addition to large bladder stones that can be treated with holmium laser lithotripsy. Teich man et al. found that the application of a 70-degree lateral fiber resulted in a faster and more effective lithotripsy procedure. Holmium laser can also be safely applied to the treatment of special stone patient groups such as pregnant women, pediatric patients [13] and bleeding bodies.
1) Main current intracavitary lithotripsy methods
(1) Pneumatic ballistic lithotripsy
High-pressure gas pushes the bullet body in the handle to impact the near segment of the metal probe at high speed for a short distance, and then instantaneously transmits the energy to the stone through the longitudinal vibration of the probe to break up the stone. The general frequency of 1-12Hz, no thermal effect, no thermal damage to the tissue. The probe can be selected with different thickness, large amplitude, high efficiency of stone fragmentation, tiny movement of stones, and stone fragments to be removed by flushing, instrumentation or natural stone removal.
(2) Electrohydraulic lithotripsy (EHL)
After the successful application of EHL for intravesical lithotripsy by Rose and Goldberg as early as 1960s, it has been widely used for the treatment of intracavitary ureteral and renal stones with the continuous improvement of electrodes. The principle of EHL is that the electrical energy stored in a capacitor is rapidly discharged through the electrode in water to form a high energy density plasma zone at the tip of the electrode. The electrical energy is converted into light, heat, force and acoustic energy in an instant, producing a blue spark that generates high heat in a small area, causing the surrounding flushing fluid to vaporize into small bubbles moving forward at high speed, forming a liquid shock wave that shatters the impacted stone.
The first use of EHL is with a 6F EHL probe, which is guided by X-ray fluoroscopy into the stone. The use of a large 9F probe is better for stone fragmentation, but because of the electric field generated during EHL stone fragmentation, and the inevitable presence of a small amount of urine electrolytes in the urinary tract, in addition to mechanical damage to the probe. There is also the possibility of electrical damage to the urinary tract, and approximately 40% of patients develop urinary extravasation after EHL treatment. Recently, a smaller diameter 1.6F EHL probe has been introduced, which can pass through the working lumen of the ureteroscope smoothly. The small diameter probe has relatively less influence on the lumpectomy flushing channel and can always ensure a clear view of the scope.
(3) Laser lithotripsy
In 1995, Denstedt first reported the Holmium laser intracavitary lithotripter for the treatment of upper urinary tract stones, and in the following decade, the laser technology has been developed. The laser technology has evolved rapidly in the last decade, with great improvements in laser fibers and energy generation systems, from pulsed dye lasers to the more popular holmium laser, further broadening the application of the holmium laser in urology, which is capable of not only crushing urinary stones of any composition, but also of tissue cutting and coagulation, and can be used intracavernally for pelvic ureteral junction stenosis, ureteral stricture dissection, and transurethral Prostate enucleation.
Holmium laser is pulsed with an emission time of 0.25s and an instantaneous power of 10KW, which is sufficient to crush stones of various compositions and densities, with a tissue penetration depth of <0.5mm and minimal tissue damage. Holmium laser fibers are available in 200, 365 and 555 μm for application through flexible, semi-rigid and rigid ureteroscopes, respectively. Years of practice in clinical applications have shown that holmium laser is safe and effective in the treatment of ureteral stones and kidney stones, and it has now become one of the main treatment methods for ureteral stones.
(4) Ultrasonic lithotripsy
Ultrasonic lithotripsy is performed by generating continuous ultrasound waves through the ultrasound generator, producing mechanical vibration energy in the transducer, and then transmitting it along the metal probe (i.e. ultrasonic lithotripsy probe) to the distal end to crush the stones through the high frequency vibration of the probe, with a frequency of 24-26 kHz and an amplitude of 30-100 microns at the tip of the probe, which only has a destructive effect on brittle and hard materials and does not damage the mucosa. The ultrasonic lithotripsy probes currently in clinical use are mostly hollow in design, and the perfusion fluid is continuously pumped out of the body, and the cooling effect prevents thermal damage while the stone fragments are also sucked out of the body, resulting in high lithotripsy efficiency.
2.Ureteral stone treatment: ESWL or ureteroscopy?
Because ureteral stones less than 5 mm in diameter have a high rate of natural expulsion, the most suitable treatment for larger ureteral stones mainly focuses on whether to choose shock wave lithotripsy? Or should we use ureteroscopy combined with endoluminal laser lithotripsy?
The 2005 EAU clinical guidelines for the treatment of ureteral stones do not recommend open surgery regardless of the size, location, and composition of the stone. Also in the American Urological Association (AUA) guidelines for the treatment of urinary stones, open ureteral surgery is not considered as first-line treatment for most patients with ureteral stones, and ureterotomy for stone extraction is considered only in those patients with anomalous ureteral anatomy and large stone size.
The development of ureteroscopic technology has significantly changed the management of ureteral stones, and rigid ureteroscopy combined with endoluminal lithotripsy can successfully treat most urinary stones. With the development of fiber optic technology and intraluminal flushing system, the use of semi-rigid ureteroscope (6.9-8.5F), and the continuous updating of soft ureteroscope and soft nephroscope, it is possible to access the upper ureter and each renal calyx within the kidney, which were previously difficult to reach by rigid scopes, more safely and easily through soft scopes and perform various intraluminal examinations and treatments.
The smaller working lumen of semi-rigid ureteroscopes and soft ureteroscopes, approximately 2.4F to 4F in diameter, requires the use of finer fiberoptic or soft lithotripsy probes, limiting to some extent the efficiency of stone management through soft scopes. The flexibility and flexibility of a soft scope can help to manage some stones in the renal calyces that are difficult to reach with a rigid scope.
ESWL is less effective and less successful than ureteroscopy, and preoperative localization is more difficult, but it is relatively noninvasive for most patients.Pace et al. reported a low success rate of repeat shock wave lithotripsy after the first failed treatment of ureteral stones, and they treated 1588 patients with the Dornier MFL 5000 lithotripter from January 1994 to September 1999 in 1593 The stone removal rate was 68% after the first treatment (1086/1593), which decreased to 46% after repeated treatment and 31% after retreatment.
ESWL is used as the method of choice for patients with ureteral stones less than 10 mm in size, and for larger proximal and distal ureteral stones, the use of ureteroscopic laser lithotripsy provides excellent treatment. Ureteroscopic laser lithotripsy can be the first-line treatment for larger ureteral stones.
When the ureteral stone is >1 cm, the obstruction is more severe, often accompanied by significant hydronephrosis, and the choice of treatment is controversial. Lam et al. reported that ureteroscopic holmium laser lithotripsy was significantly more effective than ESWL in the treatment of ureteral stones, and the clearance rate of holmium laser treatment for ureteral stones over 1 cm was 93%, while ESWL was only 50%. The holmium laser treatment rate for ureteral stones below 1 cm was 100%, while the ESWL rate was 80%, and there was no statistically significant difference between the two. Therefore, ESWL is currently considered to be the first choice for ureteral stones <1 cm, regardless of their location.
Clinical studies have shown that holmium laser has good efficacy in the treatment of ureteral stones, and 92% of patients can have their stones successfully crushed by holmium laser. However, the ultimate determinant of success does not depend on the laser alone, but on other factors such as the size and location of the stone, whether the stone is difficult to drain due to anatomical variation or ureteral stenosis.
Because of its precise vaporization and tissue cutting capabilities, the holmium laser is particularly advantageous for ureteral stones surrounded by inflammatory polyps, which are difficult to treat with other intraluminal lithotripsy methods, and most of these stones can be treated by laser excision of the polyps followed by lithotripsy, avoiding the need for open surgery. During laser lithotripsy, the quartz optical fiber has less force to push the stone and the stone position is less changed. The fragments formed after lithotripsy are small and can be easily discharged. Holmium laser also has the function of coagulation and hemostasis, which can deal with intraoperative bleeding in a timely and effective manner.
The complications of holmium laser lithotripsy are rare and are mainly caused by the ureteroscope, not by the laser itself. For large ureteral stones, failed ESWL treatment and long obstruction combined with polyps or strictures, it is better to choose Holmium laser for in vivo lithotripsy.
3. Treatment of complex kidney stones
The European Association of Urology (EAU) and the American Urological Association (AUA) have published clinical guidelines for the management of ureteral and renal stones in the last few years. In the management of renal stones less than or equal to 20 mm in diameter, ESWL is preferred, followed by PCNL, with open surgery recommended only as a third option and only for the treatment of cystine stones. However, in the management of renal stones greater than 20 mm in diameter, partial and complete antler-like stones, PCNL is recommended as the first choice, with open surgery only as the fourth option.
Recently, the AUA Expert Panel on the Treatment of Antler-like Stones also recommended PCNL as the first choice for most patients with antler-like stones, and they believe that open surgery should only be considered in those cases of large antler-like stones, especially if the patient has anatomical abnormalities of the collecting system, where removal of the stone by minimally invasive means is not expected.
Those with congenital anomalies, deformities of the skeletal system or extreme obesity that interfere with x-ray fluoroscopy and lumpectomy need to be considered for open surgery. Moreover, retroperitoneal laparoscopic surgery can replace traditional open surgery. The application of minimally invasive surgery can reduce the damage of open surgery to the kidney and maximize the protection of kidney function. Patients treated with ESWL and intracavitary minimally invasive means are significantly better than any kind of open surgery in terms of hospital stay or postoperative recovery. With the continuous maturation and advancement of percutaneous nephrological techniques, it is now used as the main means of treating complicated renal calculi.
3.1 PCNL and MPCNL
PCNL is a technique for the intraluminal lithotripsy of stones in the renal pelvis, calyces and upper ureter through percutaneous pelvic access and is an important component of endoluminal urology. Percutaneous nephrolithotomy is an emerging technique of endoluminal urology developed on the basis of percutaneous nephrostomy. In 1941, Rupol and Brown used endoscopy to remove postoperative residual stones through nephrostomy channels after open surgery, which was the earliest prototype of PCNL. Since Goodwin used percutaneous nephropuncture to successfully treat hydronephrosis in 1955 and 1976 Fernstrom and Johannson applied the percutaneous renal access established by percutaneous renal puncture to remove stones successfully, after that, the percutaneous nephrological technique was further developed and began to be widely used in the treatment of kidney stones.
The traditional PCNL requires a larger percutaneous renal pelvic channel for expansion, generally up to F26-30, with a limited angle of coarse oscillation of the mirror body, which also causes greater damage to the kidney, easily damaging the interlobular vessels or tearing the neck of the renal calyx and causing hemorrhage, with a 5% to l0% chance of failure, and sometimes requiring staged and multiple operations, and a high incidence of complications such as bleeding after surgery, which once made the traditional PCNL technique It was once difficult to promote the traditional PCNL technique. With the accumulation of clinical experience, the percutaneous nephropuncture technique has been improved and perfected, and the application of ultrasound, pneumatic ballistics, laser lithotripsy and other intracavitary lithotripsy methods has improved the success rate of PCNL treatment and gradually expanded the treatment scope.
In order to avoid the shortcomings of traditional PCNL such as large passage, serious injury and complications, domestic scholars such as Li Xun summarized more than 20 years of clinical practice and proposed minimally invasive PCNL (MPCNL), which uses microstomy method (the dilated passage is only F16-F18) and ureteroscope instead of nephroscope, thus greatly reducing the damage to the kidney and the occurrence of surgical complications by combining the use of ultrasound, pneumatic ballast and The combination of ultrasound, pneumatic ballistics and holmium laser for the first-stage lithotripsy significantly improves the efficiency of percutaneous nephrolithotripsy, shortens the operation time significantly, and broadens the scope of application.
In the past, most of the PCNL needed to be performed under X-ray fluoroscopic positioning, which was detrimental to the patient and the surgeon’s body.
1) Indications for PCNL surgery.
(1) Kidney stones larger than 2cm in diameter;
(2) Complete or partial deerstalker kidney stones;
(3) Kidney stones that have failed ESWL treatment, residual or recurrent stones after open surgery;
(4) special types of kidney stones: isolated kidney stones, horseshoe kidney stones, etc., symptomatic diverticula
(4) special types of kidney stones: isolated kidney stones, horseshoe kidney stones, symptomatic renal diverticulum stones, stones with pelvis stenosis, etc.
2) Contraindications to surgery
(1) Uncorrected systemic hemorrhagic disease;
(2) Stones combined with ipsilateral renal tumor;
(3) Severe kyphosis of the spine, unable to lie prone;
(4) Severe heart disease and pulmonary insufficiency, unable to lie prone;
(5) Uncorrected severe diabetes mellitus and hypertension;
Relative contraindications are those who take aspirin, warfarin and other drugs, and need to stop taking the drugs for more than 2-4 weeks and recheck the coagulation function normally before the procedure can be performed.
3) Positioning method and puncture path selection of PCNL.
Depending on the surgeon’s mastery of different positioning instruments, X-ray positioning, ultrasound positioning or CT positioning can be chosen, or both X-ray and ultrasound positioning can be used in combination. With X-ray localization, retrograde ureteral cannulation can be performed before surgery, and retrograde imaging via ureteral catheter during surgery can clearly show the morphology of the renal collecting system, determine the destination calyces for puncture, and guide the method of needle entry, and the location of the safety guidewire can be clearly shown during surgery to guide dilation.
The advantage of ultrasound positioning is that it can clearly show the stone site and accurately measure the distance from the skin to the target calyces, with no radiological damage to the patient or the surgeon.
There is no radiological damage, and the application of contrast agent is reduced by artificial hydronephrosis. Ultrasound navigation is accurate, and if one is skilled in ultrasound technology, the puncture can be performed under the direct guidance of the ultrasound probe, and the direction and depth of the puncture needle can be adjusted at any time with dynamic monitoring during surgery, and the portability of ultrasound can also help check for residual stones intraoperatively.
If the calyces are significantly dilated, the target calyces can be directly punctured under ultrasound localization. However, for the kidneys with fluid accumulation, ultrasound cannot clearly show the morphology of the collecting system with the help of contrast, and both X-ray and ultrasound localization can be used in combination.
CT localization is accurate and can directly puncture the renal collecting system without intraoperative contrast or retrograde intubation, but it requires a special surgical site, and the patient often needs to be moved to the operating bed after successful puncture before treatment can be performed, and CT localization is generally not used.
For complex kidney stones, the choice of puncture path has always been a difficult problem to confuse urologists. Choosing the appropriate puncture point and puncture direction to establish a suitable percutaneous renal access is the key to successful PCNL surgery, especially for the management of complex kidney stones, the puncture point and puncture path are generally selected and determined according to the location and size of the stone, the anatomical structure of the collection system, and the degree of hydronephrosis.
The previous viewpoint mainly considers the proximity to the kidney and proximity to the stone, and usually chooses the puncture path that reaches the shortest distance between the kidney and the stone, mostly choosing the point closest to the stone as the puncture point between the posterior axillary line between the 11th intercostal space and the subscapular line. For stones mainly in the upper or lower calyces, sometimes the puncture path of the upper calyces between the 10th intercostal space or the puncture path of the lower calyces under the 12th rib is also chosen (easy to puncture the hydronephrosis calyces or the puncture location close to the stone The choice of the puncture route is based on the location of the stone and the principle that the stone can be removed to the greatest extent possible. The upper ureteral stones should be selected for the upper calyces, the middle and lower calyces should be selected to avoid pleural injury, and the calyces should be selected for the calyces.
Before PCNL surgery, detailed reading of KUB, IVP film, “B” ultrasound and CT film is needed to understand the location and size of the stone, the anatomical structure of the collecting system, the degree of hydronephrosis, etc., and to select and determine the puncture point. In recent years, the development of multi-row spiral CT examination technology and the improvement of urological imaging technology, combined with spiral CT volume scanning, using computer software for post-processing such as reconstruction of images, can clearly show the structure of the kidney, and obtain a clear three-dimensional image of the entire urinary tract, including the renal parenchyma.
Multi-row spiral CT uses sub-millimeter thin layer scanning, with fast scanning speed (48mm/s), and all scans can be completed in one breath hold, eliminating artifacts caused by respiratory motion. Using urological imaging technology (CTU) can help to understand in detail the anatomical structure of the renal pelvis and calyces, the exact location of stones, and identify them with other calcified foci, and help clinical understanding of the diagnosis of any combined anatomical abnormalities of the urinary tract.
Although traditional KUB+IVP and ultrasound are simple and easy to diagnose, they cannot visualize the relationship between the stone and the surrounding tissues. For negative stones or other non-visualization caused by obstruction or fluid retention, CTU and MRU are often needed to help determine the location of the stone and urinary drainage. CTU can also help to understand the anatomical structure of the renal calyces and collecting system (intraoperative C-arm can only obtain planar image information, which cannot accurately determine the spatial relationship between the stone and the renal pelvis, calyces and collecting system), CTU can also be multi-planar reconstruction imaging, to obtain reconstructed three-dimensional images, can be rotated at any angle, cut in any direction, to observe the stone from multiple angles, and maximize the Understanding the spatial positioning of the stone in the kidney and the relationship between the kidney and the surrounding tissues can provide more detailed and richer information for the best puncture and lithotripsy plan before PCNL surgery.
The maximum density projection (MIP ) technique can be applied to determine the angle between the axis of the calyces to be punctured (mainly the axis of the posterior group of middle calyces) and the spinal plane more precisely, and combined with the volumetric reconstruction (VR) technique can simulate the puncture site and the puncture channel of the skin for PCNL on the 3D image, so as to avoid damaging the surrounding tissues and organs as much as possible, help to formulate a reasonable puncture path and reduce the occurrence of complications. To improve the success rate of intracavitary lithotripsy. For antler-shaped stones and multiple stones, one or more percutaneous renal channels can be established to retrieve stones in one or more stages according to the actual situation.
PCNL can detect stones under direct vision and remove them after adequate lithotripsy, and can be performed in one stage for lithotripsy and stone extraction, or in stages depending on the patient and the specific situation during the procedure, and can also be used with ESWL to treat stones, which is less damaging than open surgery and also less damaging than repeated multiple ESWLs compared with ESWL and open surgery. 2005 Khaled et al. performed a study on 79 cases (88 renal deerstalker-like stones) Antler-like stones, in a prospective randomized controlled study, in which 43 patients underwent PCNL and the other 45 underwent open surgery for stone extraction, showed that in the PCNL group, the incidence of intraoperative complications such as hemorrhage requiring blood transfusion, pleural injury, vascular or ureteral injury was 16.3%, which was significantly lower than that in the open surgery group (37.8% P0.05), and the operative time in the PCNL group ( 127 ± 30 vs 204 ± 31 minutes.