What kind of kidney stones can be removed using minimally invasive methods?

Author: Zhang Yi, Chief Physician, Peking University International Hospital

Reviewer: Mao Yonghui, Chief Physician, Beijing Hospital

Kidney stones are a common and frequently occurring disease in urology. The main cause is the increase of nucleation factors and the decrease of inhibitory substances, which causes some substances in urine to precipitate into crystals, aggregate into nuclei, and gradually grow into stones. It may be related to genetic, metabolic, infection and other factors.

So, should we actively treat kidney stones after discovering them?

Smaller kidney stones that do not cause symptoms, infection, or affect the kidneys can be observed without treatment. However, even small kidney stones may fall into the ureter, causing severe pain, most of which are accompanied by microscopic or macroscopic hematuria, and are one of the most common emergencies in urology.

When stones are stuck in the renal pelvis outlet or ureter, urine in the renal pelvis cannot be excreted smoothly into the ureter and bladder, resulting in increased intra-renal pelvic pressure and hydronephrosis. The compression of the renal parenchyma will affect kidney function. This situation needs to be treated promptly.

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Even if large kidney stones do not cause hydronephrosis, they can still cause adverse effects on the kidneys, such as chronic irritation and infection. Moreover, as the stones grow larger, they will sooner or later lead to symptoms such as hydronephrosis, endangering kidney function and requiring active treatment.

There are many treatments for kidney stones. Depending on the size and location of the stones, your doctor will recommend the most appropriate treatment.

For example, if the stones are smaller than 6 mm, most of them can be expelled naturally by drinking more water, increasing urine volume, or increasing activity, with the help of drugs that promote stone excretion.

If the kidney stones cannot be expelled and are less than 2 cm, extracorporeal shock wave lithotripsy is an option. Extracorporeal lithotripsy for adults generally does not require anesthesia and is slightly invasive. When extracorporeal shock wave lithotripsy is not effective, or the broken stones cannot be expelled after lithotripsy, minimally invasive endoscopic lithotripsy is recommended. At this stage, flexible ureteroscopy is one of the most commonly used methods.

When the stone is larger than 2 cm, percutaneous nephrolithotomy is the first choice. In addition, if the stone is less than 2 cm, but extracorporeal lithotripsy or soft ureteroscopy is not effective, or if the stone is located in a special position and extracorporeal lithotripsy and ureteroscopy cannot achieve the desired effect, percutaneous nephrolithotomy will also be recommended. Special cases include stones growing in the lower calyx, the lower calyx opening is relatively small, and the length of the calyx is relatively long. After the stone is broken, it needs to pass through a narrow and relatively long path to be discharged into the renal pelvis.

Percutaneous nephrolithotomy for kidney stones. The so-called percutaneous means that under the guidance of imaging, a pathway is established from the skin to the urinary tract system in the kidney. Through this artificial pathway, the endoscope is inserted into the kidney to find the stones, crush them and remove them.

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The operation usually uses epidural anesthesia or general anesthesia, and puncture is performed in the kidney area. After the puncture is successful, a guide wire is placed, and then a dilator or balloon is used to dilate, and then a sheath is placed to establish an artificial channel. The endoscope finds the stone, and laser, ballistic or ultrasonic energy is introduced to crush the stone. During the lithotripsy process, the stone is cleared out while being crushed. Finally, a drainage tube is placed according to the patient's specific situation, and the outer sheath is removed, and the operation is over.

Before percutaneous nephrolithotomy, large kidney stones required open surgery. The kidney is located deep inside, and the incision is generally required to be 20 cm or even more than 25 cm to expose the renal pelvis or kidney relatively well, and then the incision is made on the kidney to remove the stone. Open surgery is relatively traumatic and will also have a certain impact on the blood supply to the kidney, which may cause a certain degree of kidney atrophy.

Percutaneous nephrolithotomy is a technique that only creates a small channel from the skin to the kidneys, which can break up and remove the stones, greatly reducing kidney damage, effectively protecting kidney function, and significantly shortening the treatment time. Percutaneous nephrolithotomy is now a very mature and safe technique.