Holmium laser is a new type of laser generated by a pulsed solid-state laser device made from a laser crystal doped with yttrium aluminum garnet as the activation medium, sensitized chromium, thulium, and holmium as the activation ions. It can be applied to urology, ophthalmology, dermatology, gynecology and other departmental surgeries. This laser surgery is non-invasive or minimally invasive, and the patient’s treatment is very painless. Since June 2010, our department has been trying to treat 10 cases of pediatric urological diseases with holmium laser, and obtained satisfactory therapeutic effect. Now we report as follows: 1. Data and Methods 1.1 General data: 5 patients with bladder stones, 2 females and 3 males; age 14 months to 11 years. Posterior urethral stones 3 cases; male, 2-4 years old. Ureteral cysts 2 cases; 1 female, 3 years old and 1 male, 7 years old. All patients with stones underwent preoperative ultrasound and X-ray examination, with clinical manifestations of urinary frequency, urinary pain, hematuria, and dysuria. The patient with ureteral cysts presented for urinary frequency and urgency. Preoperative ultrasound, MRU and cystography were performed, all of which were right-sided, excluding duplicated kidneys, with mild dilatation of the ureter and a cyst diameter of 1.2cm-1.5cm. 1.2 Instruments and treatment methods: A 6-11F pediatric cystoscopy and an Israeli Obstetrician-Medicine Holmium laser machine were used. All children were operated under intravenous compound anesthesia. The surgical procedure was performed under a television monitoring system. Patients were placed in the lithotomy position. Surgical approach for patients with stones: posterior urethral stones were pushed into the bladder with a probe to form a bladder stone. A cystoscope was inserted into the bladder via the urethra under direct vision to observe the urethra and bladder for any abnormal lesions. After finding the stone, the holmium laser energy was adjusted to 10-30 W. A fiber optic was inserted to reach the surface of the stone, and lithotripsy was carried out from the edge of the stone, and the holmium laser was used to break the stone to a diameter of less than 2 mm under direct vision, and the larger fragments could be removed with a foreign body forceps. After withdrawing the cystoscope, a normal catheter was inserted into the bladder, and the bladder was flushed with saline to completely remove the tiny fragments. A urinary catheter is routinely left in place after surgery. Surgical method for ureteral cyst: Insert a cystoscope into the bladder via the urethra under direct vision and observe the ureteral cyst. Holmium laser energy is adjusted to 14-30 W. A fiber optic is inserted to reach the surface of the cyst, and a 1-cm incision is made at the base of the cyst with the holmium laser to drain the urine from the cyst. A urinary catheter was routinely placed after the operation. 2. Results and follow-up All cases were successfully operated in one operation. The operation time was 20-40 minutes in all cases. There were no complications such as hemorrhage, bladder perforation and water intoxication during and after surgery. The follow-up period ranged from 3 months to 2 years. There were no stones remaining in the stone cases after postoperative review. Ureteral cyst cases had atrophied cysts and ureteral dilatation disappeared in the postoperative review. 3.DISCUSSION Holmium laser machine is the newest of many lasers for surgical use and is a pulsed laser. Holmium laser technology has been used in adult urology for many years and has accumulated a large number of successful experiences, but few applications have been reported in the field of pediatric urology, and there is still a lack of corresponding technical specifications and pediatric surgical instruments that are compatible with the holmium laser.In 2007, Wang Xianglin et al[1] reported that ureteroscopic holmium laser treatment of bladder stones in children achieved satisfactory results. We began to try to use holmium laser technology to treat pediatric urological diseases in 2010, and although the number of cases is not large, we have some preliminary knowledge about it. 3.1. The lithotripsy principle of holmium laser is the photothermal reaction produced by the laser, which causes instantaneous high energy to be absorbed by the stone, and at the same time, the energy makes the local transmitter produce vaporization bubbles to impact the stone, coupled with the change of temperature on the surface of the stone and high temperature to cause a chemical reaction of the stone, which causes the stone to be broken in the end. Holmium laser has good directionality and 95% of the energy is absorbed by the surrounding 5mm water medium, so it is safe to use and not easy to cause damage to the surrounding tissues. The effect of holmium laser lithotripsy is not related to the composition of the stone. Since the holmium laser can cause displacement of the stone, in practice, the stone should be pushed away from the ureter and urethral opening and relatively fixed, and the fiber optic should be tightly attached to the stone in order to break the stone. 3.2 In the lithotripsy process, we use higher frequency and lower energy, with the parameters of 10-20 Hz and 1.0-1.5 J. This is conducive to the crushing of stones. Due to the small diameter of the pediatric urethra, larger stone fragments are not easily discharged from the body on their own, so it is required to crush the stone fragments to less than 2mm. Larger stone fragments can also be clamped with a foreign body forceps and removed together with the cystoscope. However, repeated insertion of the cystoscope is likely to cause damage to the urethra, and a urinary catheter is routinely placed in the postoperative period. 3.3 We also use holmium laser technology to treat pediatric ureteral cysts. The holmium laser should be adjusted to a higher energy level, with parameters of 14-20 Hz and 1.0-1.5 J. An incision of about 1 cm in size is made at the base of the cyst with the holmium laser. When urination occurs, the bladder pressure rises and compresses the cyst wall, causing the cyst incision to close on its own, so ureteral reflux is less likely to occur. Due to the different causes and types of ureteral cysts, the treatment methods are different. Detailed preoperative examination is necessary to clarify the typing. We believe that holmium laser treatment can be tried for simple, single ureteral cysts, using laser technology to open the window of the ureteral cyst, so that the urine drainage in the cyst is smooth and no reflux occurs. If the symptoms disappear after the operation and the X-ray shows no abnormality, further treatment may not be needed; if the effect is unsatisfactory or reflux occurs, resection of the cyst and anti-reflux ureterocystic anastomosis are still necessary. 3.4 Holmium laser technology should exclude urethral valves, stenosis, bladder diverticulum and other malformations when treating pediatric urological diseases, and for those with urinary tract infections and pyuria, they should be treated with anti-infective therapy first, and should be performed only after the infection is controlled. In order to avoid spreading of infection and bleeding caused by operation at the time of infection. 3.5 Most domestic reports of holmium laser technology are used in conjunction with ureteroscopy, but there is a single model of ureteroscopy, and the thickness of the urethra varies with the age of the child, so that a single model of ureteroscopy cannot meet the needs of treatment. We have used different types of pediatric cystoscopes with holmium laser technology to achieve good results. The optical fiber is inserted through the cystoscopic orifice, which is thin and easily broken. Great care must be taken during the placement of the optical fiber so that it does not break. In practice, you should first observe the aiming red light emitted by the optical fiber and adjust the aiming red light to the brightest, such as the head of the optical fiber without aiming red light appears to show that the optical fiber has been broken, fracture. Our early had a fiber in the cystoscope channel broken, the laser will cystoscope through the lesson. 3.6 In recent years, Hunan Zhao Yaowang et al. and Kunming Zhou Wenbo et al. have utilized holmium laser technology for the treatment of pediatric upper urinary tract stones and UPJO by percutaneous nephron puncture and have achieved satisfactory results. They have accumulated valuable experience for the use of holmium laser technology in the treatment of pediatric urological diseases. At present, the number of our cases is still small, but we believe that holmium laser technology has little damage to the mucous membrane of the urethra and bladder, is simple to operate, has reliable efficacy, is minimally traumatic, has rapid recovery of the child, and has fewer complications, and has a broad future in the treatment of pediatric urological diseases.