Transurethral Pneumatic Cystolithotripsy: A Novel Approach

Introduction

Bladder stones account for 5% of urinary tract stones in industrialized countries. ¹ The endoscopic instruments used to treat renal stones are also used to manage bladder stones. Transurethral cystolithotripsy permits stone fragmentation through mechanical lithotripsy, a pneumatic/ultrasonic lithotripter, laser energy, and electrohydraulic lithotripsy. ² Endoscopic lithotripsy may be performed through a suprapubic approach using a regular nephroscope. Stone fragmentation may be performed using any lithotripter through the nephroscope. ³ For each lithotripter, stone stabilization and fragmentation are challenges. ³ In developing countries, the availability of various advanced endoscopic instruments is limited and difficult due to financial constraints. In our study, we assessed a novel cystolithotripsy technique that involves using a semirigid ureteroscope introduced through a cystoscope sheath. Our primary end is to assess stone stabilization, stone clearance, and operative time. Our secondary end is to limit the equipment needed to perform the procedure to a ureteroscope and a cystoscope sheath, because many medical centers in Egypt lack a full endourology set, and to evaluate the incidence of postoperative urethral stricture.

Patients and Methods

Through a retrospective study conducted between May 2005 and July 2011, 53 patients with solitary bladder stones were subjected to our novel transurethral ureteroscopic pneumatic cystolithotripsy technique. The mean patient age was 54.3 years. The mean stone size was 4.8 cm. All patients were subjected to a complete physical evaluation, including digital rectal examination for male patients, and laboratory investigations, including urinalysis, complete blood count, and comprehensive metabolic profile. Radiologic evaluation, including pelvic ultrasound and plain X-rays, was performed in all patients. Noncontrast CT scans were performed for selected patients.

Surgical procedure

Under epidural anesthesia, the modified lithotomy position was used for the surgery. Diagnostic cystoscopy was performed first using a 70° optical lens, followed by the removal of the cystoscope's optical lens. A semirigid ureteroscope (8–9.8F) with a pneumatic probe (4F) was introduced through a cystoscope sheath (21F). The difference between the ureteroscope caliber and cystoscope caliber works as a draining channel that allows for better drainage of the bladder during the procedure, and irrigation fluid was connected to the ureteroscope to allow for better visualization (Fig. 1). Once the visualization was clear, the pneumatic lithotripsy started. The cystoscope sheath worked as a draining channel, allowing bladder evacuation and the collapse of the bladder over the stone, preventing stone migration and shortening lithotripsy duration. Stone immobilization allows the transmission of full pneumatic power to the stone. Periodic bladder irrigation using an Ellick evacuation-irrigation system connected to a cystoscope sheath was performed to remove stone fragments. Periodic cystoscopy was performed during and at the end of the procedure to exclude bladder injury. While keeping the cystoscope sheath in place, the ureteroscope was removed, and the cystoscope lens and bridge were reconnected to the cystoscope sheath. Keeping the cystoscope sheath in place will minimize the number of reentries into the urethra and minimize the chance of urethral injury. During the procedure, the assistant was asked to hold the cystoscope sheath to keep it in place and avoid its migration outside the bladder. Patients who had bladder neck contracture were managed, in the same session, by bladder neck incision, while those who had benign prostatic hyperplasia were managed using a transurethral resection of prostate (TURP) procedure in a different session. A 16F Foley catheter was inserted at the end of the procedure.

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FIG. 1.

Assembly of instruments used in our technique.

Results

Between May 2005 and July 2011, 53 patients (2 female and 51 male patients) with solitary bladder stones underwent transurethral ureteroscopic pneumatic cystolithotripsy in the Minia University Hospital. The mean patient age was 54.3 years. The mean bladder stone size was 4.8 cm. The mean operative time was 83 ± 21.0 minutes. The mean duration of lithotripsy and evacuation was 29.7 ± 18.4 minutes. Mild intraoperative hematuria was detected in eight patients. Stone fragments were removed completely from all patients at the end of the procedure. The average size of the stone fragments after lithotripsy was 3.6 mm, while the largest stone fragment removed was as much as 5.7 mm along its greatest dimension. Nine patients had infravesical obstruction; five of them had bladder neck contracture and were treated by bladder neck incision at the same session, while the rest had benign prostatic hyperplasia that required a TURP procedure at a separate session. Postoperative X-ray or ultrasound examination showed no residual stones. Urinary tract infection was diagnosed in three patients in the early postoperative period and treated using antibiotics. No major intraoperative complications, such as bladder perforation, were detected. All patients were managed as 1-day cases. Postoperative stone analysis showed that 11 patients had calcium oxalate monohydrate stones, 29 patients had calcium oxalate dihydrate stones, 9 patients had mixed uric acid stones, and 4 patients had calcium phosphate stones. No urethral stricture was reported in any case over 18 months of follow-up (Table 1).

Discussion

The transurethral approach to bladder stone treatment is an incision less and attractive procedure. It is the most common approach to treating bladder calculi. Ultrasonic/pneumatic and holmium laser lithotripsy are commonly used to treat urinary stone disease in urologic practices. ⁴ A cystoscope is commonly used during transurethral lithotripsy. The removal of stone fragments by pulling the cystoscope out together with the stone at its tip will cause urethral injury. To avoid this problem, the surgeon must fragment the stone as completely as possible to allow smaller fragments to be evacuated through the irrigation and aspiration technique. However, visual quality worsens during the procedure, which is parallel to the number of stone fragments. In our new technique, a semirigid ureteroscope was introduced through a cystoscope sheath. Pneumatic power was used to fragment the stones. Bladder evacuation through the cystoscope sheath allows the bladder to collapse over the stone and limits its movement. Subsequently, the stone becomes fixed and faces the ureteroscope, allowing for a faster and easier cystolithotripsy procedure. The stone is fragmented into small pieces that can be irrigated and aspirated easily through the cystoscope sheath without causing any urethral trauma. Various cystolithotripsy approaches have been described by other surgeons to treat bladder stones. Okeke and colleagues ⁵ placed a 30F Amplatz sheath through the urethra to treat five male patients with bladder stones who had an average stone size of 6.7 cm. A 26F nephroscope was introduced through an Amplatz sheath for stone fragmentation. Three out of five patients had chronic bladder outlet obstruction at an average follow-up of 9.4 months. In our technique, a 21F cystoscope was used during the procedure, which was less traumatic to the urethra than a 30F Amplatz sheath used by Okeke and colleagues. ⁵

Transurethral cystolithotripsy using a nephroscope is a fast and effective treatment modality, as described by Ener and colleagues. ⁶ Singh and Kaur compared various endoscopic treatment options for the management of bladder calculi. ⁷ They concluded that transurethral cystolithotripsy using a nephroscope is a safe treatment modality. However, the overdistention of the urinary bladder was an obstacle that required the slowing down of saline irrigation many times during the procedure. Singh and Kaur also described transurethral stone removal using a cystoscope and the reinsertion of the nephroscope more than one time to retrieve large fragments. ⁷ In our new technique, no reentry was recorded, because all stone fragments were small in size and were removed through the cystoscope sheath, thus minimizing the chance of urethral injury.

Percutaneous bladder stone removal using an Amplatz sheath placed suprapubically is an established technique. It minimizes the prolonged instrumentation of the urethra. However, a suprapubic tube increases morbidity and the length of postoperative hospital stays. ⁷ In contrast, our procedure is a 1-day procedure with minimal postoperative morbidity compared with the percutaneous approach using an Amplatz sheath.

Conclusion

The transurethral ureteroscopic pneumatic cystolithotripsy procedure is a safe and effective technique for the management of large bladder calculi. It could be an alternative technique for the management of large bladder calculi. In our technique, the bladder collapses over the stone leading to stone immobilization and, subsequently, decreasing lithotripsy duration. Stone immobilization allows the transmission of full pneumatic power to the stone. Our procedure is associated with a low risk of postoperative urethral injury because all stone fragments were evacuated through the cystoscope sheath, without contact with the urethral urothelium.