Renoscopy is primarily used to remove kidney stones from the ureter and/or kidney. It can be performed by two methods: transurethral and percutaneous renal endoscopy. Both procedures are reliable, but risks must be expected with any endoscopy.
What is renal endoscopy?
Schematic diagram showing the anatomy and structure of the kidney for kidney stones. Click to enlarge. A renal endoscopy can be performed in two ways: either transurethrally, which means through the urethra, or percutaneously, which means through the skin. Transurethral endoscopy (ureterorenoscopy, URS) mirrors the ureter and kidneys, whereas the percutaneous procedure (percutaneous nephrolitholapaxy, PCNL/PNL) focuses only on the inner cavity of the kidney (the renal pelvis). The latter method is very effective, but is much more invasive than the former. Both procedures are performed under anesthesia. Direct endoscopy of the kidney, or nephroscopy, is a so-called percutaneous procedure, meaning that it is performed through the skin. Because the skin covering is cut open, renal endoscopy is rarely performed to make a diagnosis. Primarily, the procedure is used to remove kidney stones. During a ureteroscopy, the instrument is passed through the bladder into the ureter. Ideally, the attending physician can advance the instrument to the kidney to remove the kidney stones. In both procedures, the physician works with uninterrupted monitoring by an ultrasound machine or camera.
Function, effect and goals
Renoscopy is a therapeutic method. The most important function of percutaneous renal endoscopy is to remove kidney stones, which are found in the inner cavity of the kidney and cannot pass through the ureter because of their size. The large kidney stones that cannot be crushed are also removed by percutaneous renal endoscopy. Stones larger than 3 cm in diameter are removed this way. In case of kidney congestion, renoscopy can also be helpful by draining the urine from the renal pelvis. Kidney congestion occurs when urine cannot drain toward the bladder because of a blockage in the ureter. During a percutaneous renal endoscopy, the patient must lie on his or her stomach so that the attending physician can make an incision through the skin of the lateral abdominal region. This incision allows the penetration of an endoscope, which is advanced to the kidney. Thus, the inner cavity of the kidney, the renal pelvis, is punctured. The whole procedure is controlled with an ultrasound machine because it is a very precise procedure and because otherwise the doctor would not be able to see exactly where the endoscope is. After the instrument is inserted, the stone is crushed by a medical “jackhammer”, laser or ultrasound, and the fragments are removed directly. In a ureterorenoscopy, the stones are removed “naturally.” The instrument is passed through the bladder into the ureter, possibly as far as the kidney. The stones are either pulled out or, if they are too large, crushed beforehand with laser beams or ultrasound. The steps in this procedure are also followed directly. Thanks to modern technology, very small cameras can be placed at the tip of the device. The ureter is usually prepared for the procedure by inserting a splint. This splint is used to relax the ureter, making the procedure less risky.
Risks, side effects, and hazards
Just like all medical procedures, renal endoscopy carries risks and complications. These include intraoperative or postoperative bleeding or injury to the ureter and renal pelvis. In addition, fever may occur as a consequence of the procedure. Very rarely, kidney loss may occur. It can happen that the irrigation fluid, which is needed for the reflection, gets into the bloodstream. This dilutes the blood. Neither transurethral nor percutaneous surgery should take place in the presence of an untreated urinary tract infection. In the case of coagulation disorders, the two methods are recommended only in urgent cases. Percutaneous renoscopy is prohibited during pregnancy. This method is also contraindicated in case of a tumor in the access area. The likelihood of the above complications depends on the size and location of the stones or previous operations.
