1.What is ureteroscopy?
First, I would like to introduce the ureter in general. The ureter is a long, thin tube with an average diameter of 0.4-25px, roughly equivalent to the thickness of 40-100 hairs (estimated at 100μm in diameter for one hair). The ureter is located deep in the abdomen, one on each side, starting from the renal pelvis and ending at the bladder.
A ureteroscope is a slender instrument with a camera system at the head end that can be inserted retrograde through the body’s natural urinary tract through the urethra and bladder for diagnosis and treatment, and is characterized by the absence of a body wound for ureteroscopic procedures. At present, ureteroscopy technology is used not only for the treatment of ureteral stones, but also in urological diseases such as complex urinary stones, ureteral stenosis and postoperative urinary leakage.
2.What types of ureteroscopes are there?
Ureteroscopes can be divided into two types: rigid and flexible scopes.
Ureteroscopes can be divided into long ureteroscopes (40-1150px) and short ureteroscopes (875px) according to their length. It can be further divided into ureteral coarse mirror (12.5F-13.5F) and ureteral fine mirror (6.9-9.4F) according to the diameter thickness. Short scopes are mainly used for the diagnosis and treatment of ureteral diseases in the lower part of the ureter.
Soft ureteroscopes, or what we call fiberoptic ureteroscopes, are divided into actively curved and passively curved shapes. The soft mirror is mainly used to observe part of the internal structure of the kidney and the upper ureter.
3.What are the advantages and disadvantages of fiberoptic ureteroscopy?
Fiberoptic ureteroscope, also called soft ureteroscope, is different from the traditional rigid ureteroscope, which is a soft lumpectoscope with the head end that can be bent at will, so it can reach the area inside the kidney that cannot be reached by the traditional rigid ureteroscope. Ureteroscope is mainly used for kidney stones below 50px and stones in the upper ureter, especially for stones in the lower renal calyces.
Advantages: 1. Minimally invasive surgery; fiber soft ureteroscope enters the ureter and kidney through the natural channel of human body, shattering stones without injuring the kidney and leaving no wound on the patient’s body surface; 2. nephrolithotomy, ureteroscopy is shorter than percutaneous nephrolithotomy, with shorter average hospital stay and fewer complications such as bleeding.
Disadvantages: 1. Pre-operative antegrade tube, post-operative self drainage of stones; fiberoptic ureteroscope is slightly thicker than normal ureter, so preoperative pretreatment of ureteral dilatation is needed to drain the infected urine in advance and intraoperative endoscope can reach the kidney smoothly. After soft mirror lithotripsy, most of the stone powder is directly discharged out of the body, and fine lithotripsy particles need to be discharged by themselves, which takes longer time to discharge, and sometimes causes ureteral obstruction requiring extracorporeal shock wave lithotripsy or ureteral rigidoscopy treatment; 2. Higher cost; compared with traditional ureteral rigidoscopy, ureteral soft mirror surgery is more expensive.
4.Ureteroscopy, what is the principle of lithotripsy?
There are many kinds of lithotripsy methods in vivo: ① ultrasonic lithotripsy; ② fluid electric lithotripsy; ③ laser lithotripsy; ④ pneumatic or electronic ballistic lithotripsy, etc. Ultrasonic lithotripsy uses electrical energy to convert into sound waves, which generate mechanical vibration energy in the ultrasound transducer and are transmitted to the ultrasound probe rod through the ultrasound electrode, causing its tip to vibrate longitudinally and producing a lithotripping effect when in contact with a hard stone. Liquid electro-lithotripsy is a high voltage discharge of lithotripsy electrodes in liquid, and the shock wave of certain electric power vibrates in water, causing the release of gas dissolved in water and forming tiny bubbles, and the gas inside the bubbles expands and collapses within a very short time of shock wave movement, forming liquid shock wave lithotripsy. Laser lithotripsy mainly uses the photothermal effect on the stone to produce bubble cavitation and disintegrate the water-containing stone rapidly. The principle of pneumatic ballistic lithotripsy is that the compressed air enters the ballistic channel through the air injection port, so that the high speed movement of the warhead repeatedly hits the impact rod inside the handle of the lithotripsy device, causing the impact rod to produce longitudinal vibration to break the stone.
5.Does the laser cause damage to the kidney tissue?
The holmium laser used in our department, for example, has a shallow penetration and does not easily damage the surrounding tissues or deep tissues. The energy produced by the holmium laser is absorbed by the water in the stone, causing the stone containing water to “self-destruct” into powder in a short period of time, which is called the “drilling effect”. The excess energy is rapidly absorbed by the surrounding water, causing no thermal damage to the tissue. Holmium laser has short pulses and high power to break up stones in a short period of time without significant impact force, which makes stones less likely to move and reduces the chance of accidentally injuring kidney tissue. In addition, in some optical fibers there is an emitting guiding laser, once this guiding laser cannot see the stone, the laser machine will refuse to work.
6. Who can use ureteroscopy for kidney stones?
Ureteroscopic lithotripsy is indicated for: 1) stones in the middle and lower ureter; 2) ureteral stones that have failed conservative treatment or extracorporeal shock wave lithotripsy; 3) stones that cannot be lithotripped by extracorporeal shock wave; 3) stones that have remained in the ureter for too long and are encapsulated by polyps.
For some of the kidney stones, ureteral flexible scopes can also be addressed. Such as 1, stones less than 50px; 2, kidney stones not suitable for extracorporeal shock wave lithotripsy; 3, both ureteral stones and kidney stones; 4, extreme obesity
Ureteroscopy is not recommended for stones with the following conditions: 1, uncontrollable bleeding disorders; 2, pregnant women; 3, severe cardiopulmonary and renal insufficiency that precludes the procedure; 4, uncontrolled infection.
7.What tests should be done before ureteroscopy? Why?
Before surgery, we need to make a clear diagnosis. In addition to the routine physical examination, we also need imaging examinations, such as B-ultrasound, X-ray or CT, in order to clarify the location, size and number of stones, and to understand the characteristics of the ureteral alignment, stenosis or distortion, so as to reduce the possibility of surgical failure.
The rest are routine blood, clotting time, liver and kidney function, blood sugar, urine routine, urine bacterial culture, electrocardiogram and chest fluoroscopy for routine surgery.
8.Is the anesthesia for ureteroscopy general?
Ureteroscopy generally uses combined lumbar and epidural anesthesia, which is commonly known as “semi-anesthesia”. Lumbar anesthesia combined with epidural anesthesia can take the advantages of two kinds of anesthesia, reduce the amount of anesthetic drugs, the analgesic effect is exact, the muscle relaxation effect is good, and the impact on breathing is small, which greatly reduces the incidence of headache, nausea, vomiting and other side effects of anesthesia after anesthesia, so patients do not have to worry about anesthesia bringing great harm to the body.
9.What complications will occur during ureteroscopy? How to deal with them?
The main complications during ureteroscopy are ureteral injuries, including pseudo-tract formation, perforation, rupture and avulsion.
Pseudotract formation injury is a relatively minor injury, and even if the correct ureteral tract is found and a stent tube is left in place, the patient can recover on his or her own after surgery.
If the ureteral perforation is small, the postoperative placement of a stent tube can heal on its own. If the perforation is large, producing significant intraoperative back pain or abdominal distension, and it is estimated that the procedure cannot be completed within a period of time, modified open surgery is required.
Intraoperative ureteral rupture or avulsion is the most serious complication of ureteroscopic surgery, and once avulsion or rupture is detected, the surgery needs to be aborted immediately and replaced by open anastomotic ureteral surgery. Of course, there are many reasons for complications of surgery, such as long time of stone imbedding, edema or polyp formation in the mucosa, twisted and deformed ureter, rough surgical action or inadequate anesthesia, and un-relaxed ureter.
Therefore, preoperative examination, adequate knowledge of the ureter, good intraoperative anesthesia, and gentle intraoperative operator movements are all measures to avoid these complications. This surgery is one of the most common surgeries in our department, and years of surgical experience can escort patients during the operation.
10.What are the complications after ureteroscopy?
Early complications after ureteroscopy include hematuria, fever, renal colic, and urinary extravasation; late postoperative complications include ureteral stenosis or occlusion, and ureteral stent tube stone formation.
In general, ureteral surgery does not bleed heavily, and hematuria is mostly caused by mucosal injury, which can heal spontaneously. If there is more bleeding, appropriate hemostatic drugs can be applied.
Postoperative fever is usually caused by infection caused by the original stone, and in the case of intraoperative irrigation, bacteria retrograde into the blood, causing fever. Preoperative application of antibiotics, intraoperative aseptic operation, adequate postoperative drainage and strengthening anti-infection are also possible to solve or avoid the problem of fever.
Postoperative renal colic, manifested as lumbar and abdominal pain, is mostly caused by ureteral edema, irritation of the ureter by blood clots or stone fragments or paracolic ureteral reflux. The pain can be relieved in a short period of time by giving antispasmodic, analgesic and sedative treatment.
Damage to the deep ureter during surgery and postoperative scar contracture can easily cause ureteral stenosis or occlusion. Careful operation during surgery to minimize ureteral mucosal damage or intraoperative damage to the mucosa can also prevent the formation of ureteral stenosis by choosing the appropriate ureteral stent tube and retention time according to the actual situation.
Some patients are prone to stone formation or have left the ureter in place for too long, and stones are often formed on the stent. Therefore, after returning to the hospital after surgery to remove the drainage tube, we usually arrange abdominal plain film examination to clarify the presence of ureteral stone formation. If the stones are small, ureteral extraction can be performed on a trial basis. If the stones are large, they can be removed after extracorporeal shock wave lithotripsy or direct ureteroscopic lithotripsy, depending on the situation.