Abstract: Objective: To investigate the clinical effect of ureteroscopic pneumatic ballistic lithotripsy in the treatment of lower urinary tract stones. METHODS: Ureteroscopy and pneumatic ballistic lithotripter were applied to treat 18 cases of lower urinary tract stones. RESULTS: All patients were successfully treated at one time, and the lithotripsy time was 5-25 min. There were no significant postoperative complications such as bleeding, infection and urethral stricture. Conclusion: Ureteroscopic pneumatic ballast lithotripsy is simple, safe, effective and ideal for the treatment of lower urinary tract stones Keywords: lower urinary tract stones; ureteroscopy; pneumatic ballast lithotripsy; We applied ureteroscopy combined with pneumatic ballast lithotripsy to treat 18 cases of lower urinary tract stones from June 2006 to June 2007, and achieved satisfactory results, which are reported below. The clinical manifestations were painful urination, hematuria, interruption of urinary flow and difficulty in urination, including acute urinary retention in 4 cases. The anterior urethral stones were directly palpable on physical examination, and the posterior urethral stones were palpable by rectal examination, and all patients were confirmed by ultrasound and abdominal plain film. 1.2 Treatment The German Wolf F8/9.8 ureteroscope and the Swiss EMS pneumatic ballast lithotripter were used. 18 patients were treated with continuous epidural anesthesia or intravenous combination anesthesia in the lithotomy position. A 2.0 mm diameter lithotriptic probe was applied to treat urethral stones by pressing the stones against the urethral wall as far as possible. The bladder stones were treated with less water to make the bladder empty, and the bladder wall and the lithotriptic probe were used to fix the stones and increase the success rate of lithotripsy. A single or continuous pulse is used to crush the stones. For pediatric lower urinary tract stones, it is best to crush the stone to < 2 mm and the stone can be discharged by itself; for adult lower urinary tract stones, crush the stone to < 5 mm and flush it out with Ellik flush, and try to remove the stone without lithotripter to avoid increasing the chance of urethral injury. Postoperatively, antibiotics were applied appropriately to prevent infection, and the decision to retain the ureter was made according to the situation. In two cases, the posterior urethral stones were pushed to the bladder during lithotripsy, and then bladder pneumatic ballast lithotripsy was performed; in one case, bladder stones were combined with bladder tumor, and TURBT was performed; in one case, TURP was performed after lithotripsy in a patient with prostatic hyperplasia. Four patients with anterior urethral stones had a little blood leakage from the urethral orifice after surgery, which resolved on its own after 5 h without special treatment. No complications such as urethral stricture occurred during the follow-up period of more than 6 months. Lower urinary tract stones can cause painful urination, interruption of urine flow, difficulty in urination, and even acute urinary retention, which is one of the common diseases in urology and often requires emergency treatment. For lower urinary tract stones, they are mainly treated by extracorporeal shock wave lithotripsy (ESWL), transcystoscopic mechanical lithotripsy (vigorous lithotripter trans-urethral intravesical lithotripsy) and open surgery in China. The application of ESWL treatment with X-ray and shock wave is likely to cause damage to the gonads (especially in pediatric patients) and should be chosen with clinical caution, while transcystoscopic mechanical lithotripsy (vigorous lithotripter transurethral intravesical lithotripsy) and open surgery have certain complications. The combined application of pneumatic ballast lithotripter and ureteroscope provides us with new ideas for the treatment of lower urinary tract stones. The principle of pneumatic ballistic lithotripter is that the energy generated by compressed gas drives the bullet body inside the lithotripter handle, so that the bullet body pulses to impact the stone and break it up [1]. Ureteroscopy combined with pneumatic ballistic lithotripsy has high success rate, short time and fast recovery in the treatment of ureteral stones [2], and has made great progress in the treatment of ureteral stones in recent years [3,4,5], and it has also been used in the treatment of renal stones [6]. Given the successful experience of ureteroscopy combined with pneumatic ballast lithotripsy in the treatment of ureteral stones and renal stones (minimally invasive skinned ureteroscopic pneumatic ballast lithotripsy for renal stones), we applied it to the treatment of lower urinary tract stones and achieved good results. We have experienced that ureteroscopy combined with pneumatic ballast lithotripsy for lower urinary tract stones has the following advantages: (1) less trauma: because the ureteroscope is relatively thin, it causes less damage to the urethra compared with cystoscopic lithotripsy. (2) Less complications: low incidence of postoperative bleeding, infection and urethral stricture. (3)The operation is simple and relatively easy to master. (4) Lithotripsy under direct vision, with high success rate. Precautions should be taken in lithotripsy: (1) The scope must be entered under direct vision to maintain a clear view and avoid causing urethral injury. (2)The bladder stones should be handled with less water injection to make the bladder empty, and the stones should be fixed using the bladder wall and the lithotripsy probe to improve the efficiency of lithotripsy. (3) Try to crush the stones as much as possible. For pediatric lower urinary tract stones, it is best to crush the stones to < 2 mm, and the stones can be expelled by themselves; for adult lower urinary tract stones, we experience that stones < 5 mm can be flushed out with Ellik flushers, and try to remove the stones without lithotripters to avoid increasing the chance of urethral injury. (4) For lower urinary tract stones due to lower urinary tract obstruction the etiology should be removed after lithotripsy. (5) Urethral stones should be lithotripped in situ as much as possible to avoid entering the bladder and increasing the lithotripping time. (6) Attention should be paid to the possibility of bladder stones combined with bladder tumor. We believe that the indications for ureteroscopy combined with pneumatic ballast lithotripsy in the treatment of lower urinary tract stones are: (1) Lower urinary tract stones in pediatric patients. (2) Adults with hard lower urinary tract stones and unsuccessful ESWL lithotripsy. (3) Lower urinary tract stones causing acute urinary retention. (4) The stone is embedded in the urethra and forcibly pushed back to the bladder, which may cause urethral injury. (5) Most of the stones at the end of the ureter have entered the bladder. (6) Large stones. (7) Those who have prostatic hyperplasia causing lower urinary tract obstruction combined with bladder stones and are not suitable for open surgery. In summary, the treatment of lower urinary tract stones by ureteroscopy combined with pneumatic ballast lithotripsy is simple, safe and reliable, with high success rate, little trauma, few complications and fast recovery. We believe that it can be the preferred method for the treatment of lower urinary tract stones.