Totally ultrasound-guided percutaneous nephrolithotomy in a patient with severe scoliosis: a case report and review of the literature

Abstract

Complete staghorn calculi present one of the most challenging conditions in managing upper urinary tract stones. The complexity of treatment increases significantly when combined with severe scoliosis, particularly in patients with a Cobb angle exceeding 90°. This case report describes the treatment of a patient with severe scoliosis, characterized by a Cobb angle greater than 90°, who also presented with complete staghorn calculi. The patient successfully underwent single-stage, totally ultrasound-guided, tubeless mini-percutaneous nephrolithotomy, achieving excellent stone clearance without complications. This report aims to enhance the understanding of diagnosing and managing severe scoliosis in patients with complete staghorn calculi and to highlight the efficacy and safety of totally ultrasound-guided mini-percutaneous nephrolithotomy as a surgical approach.

Introduction

Staghorn calculi coexisting with severe scoliosis are rare in clinical practice and present significant surgical challenges due to altered anatomical structures.^1,2 Mini-percutaneous nephrolithotomy (mini-PCNL), known for its minimal nephrostomy tract dilation, reduced risk of vascular injury during surgery, ³ and enhanced precision in selecting puncture sites compared with standard PCNL, is considered an optimal approach for managing severe spinal deformities accompanied by complete staghorn calculi. ⁴ This case report presents the treatment of a recent patient in our department, highlighting the complexities and considerations involved in such cases. The reporting of this study adheres to the CARE guidelines. ⁵

Case presentation

Patient information

A 64-year-old man, diagnosed with polio-induced scoliosis in childhood and presenting with a Cobb angle exceeding 90° (Figure 1) along with bilateral paraplegia, was admitted because of bilateral staghorn calculi identified 3 years prior. The patient was 145 cm tall and weighed 40 kg. Computed tomography (CT) revealed bilateral staghorn calculi, with notable cortical atrophy in the left kidney and a pronounced scoliotic curve. The right kidney contained a complete staghorn calculus measuring 45 mm × 35 mm × 66 mm (Figure 2). Preoperative glomerular filtration rate measurements showed 11.1 mL/minute for the left kidney and 42.4 mL/min for the right. Elevated white and red blood cell counts were noted in the preoperative urinalysis. The patient underwent 1 week of preoperative antibiotic therapy, with urine cultures yielding negative results.

Figure 1.

Three-dimensional reconstruction of the spine, showing a Cobb angle exceeding 90°.

Figure 2.

Three-dimensional reconstruction of the right kidney’s staghorn calculus, measuring 45 × 35 ×66 mm.

Surgical procedure

To establish artificial hydronephrosis, an F8.5 ureteroscope was initially inserted through the urethral opening. However, because the ureteral openings in the bladder were positioned more laterally than usual, cannulation was not possible with this instrument. Consequently, the ureteroscope was replaced with a flexible cystoscope. Using a loach guidewire for guidance, access to the right ureteral opening was successfully achieved. An F7 ureteral catheter was then advanced along the guidewire, extending approximately 25 cm into the right renal pelvis, where urine overflow confirmed proper placement.

For the next phase, the patient was carefully positioned prone, with special attention given to accommodating his chest and spinal deformities. Additional precautions were taken to protect the patient’s protruding spine and ribs while in the prone position. Because of his history of poliomyelitis and resultant muscular atrophy in the legs, cushioning was placed under the knees for added protection (Figure 3). Following routine disinfection and draping, sterile saline was injected through the ureteral catheter. Ultrasound examination revealed multiple “camel hump signs,” characteristic of staghorn calculi in the right kidney, prompting a percutaneous nephroscopic puncture at the 11th rib, adapted to the patient’s unique anatomical challenges. Under ultrasound guidance, a percutaneous needle was inserted horizontally at the level of the 11th rib, between the right scapular angle line and the posterior axillary line, targeting the middle calyx of the right kidney. Placement within the collecting system was visually confirmed. After withdrawing the needle core, a metal guidewire was introduced. A 1.0-cm incision was made along the puncture needle’s path, and the guidewire was secured as the needle was removed. A percutaneous dilation sheath was advanced over the guidewire and gradually dilated from F8 to F18 to accommodate the large calculi. An F18 percutaneous nephroscopic sheath was then installed. Next, an F8.5 ureteroscope was inserted through the sheath, confirming proper alignment of the puncture channel. Upon examination, multiple dark brown, hard staghorn calculi, each measuring approximately 6.6 cm, were identified in the upper, middle, and lower calyces and the pelvis of the right kidney, accompanied by polyp growth.

Figure 3.

Prone positioning of the patient, carefully adjusted to accommodate significant chest and spinal deformities.

Under nephroscopic guidance, a 550-µm thulium laser fiber was inserted, set to a power of 3.0 W and a frequency of 20 Hz. This configuration enabled continuous laser operation, effectively fragmenting the staghorn calculi within the right kidney’s calyces and pelvis into smaller pieces. The fragments were efficiently extracted using a stone basket along the nephroscopic tract. A thorough examination of the punctured calyx, pelvis, and upper segment of the right ureter confirmed the absence of residual stones. Continuing with the procedure, a zebra guidewire was advanced antegrade into the right ureter, extending to the bladder. The ureteral catheter was then withdrawn to the external urethral opening. A double J stent (size F6) was carefully placed along the guidewire, with one end positioned in the bladder and the other in the right renal pelvis, all under nephroscopic guidance. No active arterial bleeding was observed during the procedure. Subsequent ultrasound examinations revealed no dense shadows, indicating no need for further puncture. The zebra guidewire was kept securely in place within the channel.

The sheath was methodically withdrawn, ensuring hemostasis through the metal built-in sheath, as described in previous studies. ⁶ A self-designed, innovative hemostatic sheath was used to electrocoagulate bleeding identified in the percutaneous renal channel during routine checks. The surgical site was thoroughly inspected for significant arterial or venous bleeding, and ultrasound confirmed the absence of substantial perirenal fluid accumulation. The urine in the catheter appeared light red and free of significant clots. The surgical incision was then aseptically dressed, and an inventory check verified that all surgical instruments and gauzes were accounted for, marking the conclusion of the procedure. The surgery was successfully completed, characterized by satisfactory anesthesia, minimal blood loss estimated at approximately 20 mL, and no need for blood transfusion. The patient was safely transitioned back to the ward, and the retrieved stone fragments were handed over to his family.

Postoperative course

Prior to surgery, the patient’s creatinine level was 124 μmol/L. Postoperatively, a significant reduction to 109.6 μmol/L was observed. His hemoglobin level remained relatively stable, measuring 103 g/L before surgery and 101 g/L afterward. Postoperative CT scans confirmed excellent stone clearance (Figure 4). The ureteral stent was verified to be correctly positioned. Stone composition analysis, performed using postoperative infrared spectroscopy, revealed that the stones were primarily composed of dihydrate and monohydrate calcium oxalate. Although the CT scan showed some residual fragments, we consider the procedure to have successfully achieved its primary goal: clearing the complete staghorn stone to a significantly improved status. The remaining fragments are deemed clinically insignificant and unlikely to cause future complications.

Figure 4.

Three-dimensional reconstruction of the postoperative computed tomography image, demonstrating successful stone removal.

Discussion

Scoliosis involves three-dimensional structural and morphological changes to the spine, affecting approximately 1% of the population. It is often associated with thoracic deformity, visceral displacement, hip joint stiffness, and pelvic tilt. The primary clinical impact of scoliosis is on cardiopulmonary function. Studies show that larger Cobb angles are linked to increased elastic resistance and decreased lung compliance, with a Cobb angle of greater than 90° classified as severe scoliosis. ⁷

The epidemiology of kidney stones in patients with severe scoliosis is poorly documented, resulting in a lack of definitive treatment strategies and limited reports on management. Treating kidney stones in these patients poses significant challenges in urology. Although Montero et al. reported the use of extracorporeal shock wave lithotripsy for treating kidney stones in patients with severe scoliosis, this approach is associated with considerable risks and difficulties. Its application is limited due to potential complications, such as postoperative intestinal bleeding. Furthermore, extracorporeal shock wave lithotripsy is generally ineffective for managing complete staghorn calculi because it cannot completely clear large stone burdens. ⁸ Conversely, open surgery, although a conventional alternative, involves significant trauma and is less preferred due to its highly invasive nature.

PCNL in patients with scoliosis is rarely reported. According to Culkin et al., the average patient undergoes approximately 2.04 surgeries, achieving a success rate of 90%. ⁹ However, subsequent studies reported a considerably lower stone clearance rate in patients with scoliosis than in the general population (88.6% vs. 98.5%). ¹⁰ The highest documented success rate, 96%, involved patients who required secondary and even tertiary surgeries. The rate of postoperative complications in patients with scoliosis is notably higher, largely because of increased risks from anesthesia, prolonged bed rest, and heightened susceptibility to infection and bleeding. ¹¹ Culkin et al. reported a severe complication rate of 20%, in stark contrast to the 1.4% rate observed in the general population. ¹¹ Other studies have noted severe complication rates ranging from 7% to 12%, with the most common complications including urosepsis, pneumothorax, perinephric abscess, and respiratory arrest. Nabbout et al. cited a transfusion rate of 28.6%. ¹² Recent literature has supported the use of tubeless PCNL in select cases, demonstrating significant reductions in postoperative discomfort, analgesic requirements, recovery time, and hospitalization duration. ¹³ In this case, our center employed a novel hemostatic inner sheath for hemostasis, eliminating the need for a nephrostomy tube. Postoperatively, the patient’s hemoglobin level remained stable, and urine output was clear.

The key surgical insights gained from this case are as follows. First, in patients with severe scoliosis, twisted ureters and displaced ureteral openings can complicate the placement of a ureteral catheter. This often requires the use of a flexible cystoscope to locate the ureteral opening and guide the placement of a guidewire. Second, the coexistence of scoliosis with thoracic deformities and visceral displacement adds complexity to the selection of appropriate surgical positions and puncture sites during PCNL, requiring careful planning to avoid the pleura and intestines. Third, accurate positioning during surgery is crucial for establishing an effective percutaneous renal tract in patients with spinal deformities and kidney stones. Curvature of the spine toward the affected side can facilitate exposure and access to the affected kidney, whereas curvature toward the healthy side reduces surgical space, increasing procedural difficulty and risks. Fourth, spinal deformities significantly increase the risk of kidney stones and infections, ¹⁴ likely because of anatomical irregularities in the spine and ureters that disrupt normal urine flow, leading to hydronephrosis and urinary tract infections. To minimize the risk of intraoperative infections, preoperative antibiotic treatment to ensure sterile urine is essential. Fifth, the use of our novel hemostatic inner sheath for vascular closure post-puncture proved to be both safe and effective in this complex case, allowing us to forgo the use of a nephrostomy tube. Finally, ultrasound guidance plays a critical role in percutaneous renal aspiration and intraoperative monitoring. It facilitates tasks such as channel dilation, exploration for residual stones, and detection of perirenal effusion, while eliminating the need for repeated X-ray exposure.

Conclusions

Complete staghorn calculi represent one of the most challenging scenarios in kidney stone management, particularly when combined with severe scoliosis, which significantly increases the complexity of surgical intervention. This case report highlights the successful use of ultrasound-guided mini-PCNL, incorporating a novel hemostatic inner sheath for in-channel hemostasis, to achieve satisfactory stone clearance without severe complications. Therefore, totally ultrasound-guided mini-PCNL stands as a viable and effective surgical option for managing such complex cases.