Virtual reality-enabled precision in percutaneous nephrolithotomy - strategic access planning in a malrotated kidney: A case report

Abstract

BACKGROUND

Percutaneous nephrolithotomy (PCNL) can be technically challenging in patients with congenital renal tract anomalies, particularly when establishing safe and accurate percutaneous access. Malrotation of the kidneys is the most common type of renal anomaly and alters the spatial relation between the hilum and calyceal system relative to their normal anatomical position. The use of fluoroscopic landmarks in these cases has been shown to be unreliable because of the altered spatial relations. There is an increased risk of access-related complications secondary to abnormal anatomy. The application of virtual reality (VR) based on three-dimensional reconstruction represents a new approach for improving the surgeon’s ability to understand spatial anatomy prior to performing a procedure.

CASE SUMMARY

A 57-year-old woman was referred to our institution for right-sided loin pain of 1 year’s duration. The patient underwent computed tomography urogram, which showed a malrotated right kidney with an anterolateral hilum. There was evidence of a renal pelvic calculus measuring 2.4 cm × 1.7 cm (1569 Hounsfield units). Mild hydronephrosis was observed. Using DICOM data derived from the computed tomography images, a three-dimensional VR model was created, allowing visualisation of the renal axis, pelvicalyceal anatomy, surrounding rib cage, and major vascular structures. Utilising this immersive environment to plan the procedure allowed us to identify the posterior lower calyx as the optimal site for percutaneous access and to delineate a subcostal percutaneous trajectory to minimise procedural risks. The VR-based operative plan was successfully translated into the operative setting, where we achieved single-tract access, complete stone removal, and an uncomplicated postoperative recovery.

CONCLUSION

This case demonstrates the feasibility of VR-assisted preoperative planning for PCNL in anatomically complex kidneys.

Key Words: 3D reconstruction; Endourology; Pelvic calculus; Percutaneous nephrolithotomy; Percutaneous renal access; Renal malrotation; Virtual reality; Case report

Core Tip: Immersive virtual reality reconstruction from computed tomography DICOM data may assist with preoperative access planning during percutaneous nephrolithotomy in anatomically complex kidneys by improving appreciation of calyceal orientation and access trajectory.

INTRODUCTION

Percutaneous nephrolithotomy (PCNL) is the gold standard for treating renal calculi larger than 2 cm or complex renal stones[1]. Safe and accurate percutaneous access is the most important aspect of PCNL and has a direct effect on the success of surgery and complication rates[2]. Renal malrotation is a rare congenital anomaly that causes alterations in calyceal orientation and displacement of the renal hilum[3]. These anomalies can cause normal fluoroscopic landmarks to become unreliable for guiding PCNL. There have been many advancements in three-dimensional imaging and virtual reality (VR) technology, allowing patient-specific anatomical visualisation to assist surgeons in surgical planning and preparation[4]. The VR platform provides surgeons with an immersive view of a three-dimensional model of the patient’s anatomy, which may help identify safer routes for percutaneous access in complex cases. However, reports describing immersive VR-guided access planning for PCNL in patients with anomalous renal anatomy are limited. We present a case of a renal pelvic calculus in a malrotated kidney, in which a VR platform was used to create a patient-specific three-dimensional model for preoperative planning of the optimal percutaneous access trajectory before PCNL.

CASE PRESENTATION

Chief complaints

A 57-year-old woman presented with intermittent right-sided flank pain that had persisted for 1 year.

History of present illness

The patient reported a dull, aching pain in the right flank, which occurred intermittently over the preceding year. These episodes were not associated with haematuria, fever, dysuria, or other lower urinary tract symptoms. Over time, the frequency of pain episodes gradually increased, prompting further medical evaluation.

History of past illness

The patient had no known medical comorbidities or history of renal stone disease, urological interventions, or renal surgery.

Personal and family history

There was no known relevant family history of urinary tract stones (urolithiasis) or congenital renal anomalies.

Physical examination

General physical examination findings were unremarkable. Abdominal examination revealed no palpable masses, tenderness, or organomegaly. Vital signs were within normal limits.

Laboratory examinations

The results of routine laboratory investigations, including complete blood count, renal function tests, urinalysis, and urine culture, were within normal limits.

Imaging examinations

Contrast-enhanced computed tomography (CECT) indicated malrotation of the right kidney. In addition to malrotation, the renal hilum of the right kidney was oriented anterolaterally. A 2.4 cm × 1.7 cm calculus was noted in the renal pelvis of the right kidney and measured 1569 Hounsfield units (Figure 1A). CECT revealed mild hydronephrosis and thickening of the urothelium of the renal pelvis. However, CECT did not reveal any abnormalities of the renal vessels or infundibular stenosis.

Figure 1 Multimodal imaging and virtual reality–guided planning of percutaneous nephrolithotomy in a malrotated kidney. A: Contrast-enhanced computed tomography coronal image demonstrating a malrotated right kidney with an anterolaterally oriented renal hilum and a hyperdense renal pelvic calculus; B: Three-dimensional reconstruction generated from computed tomography DICOM data illustrating patient-specific renal anatomy, including the malrotated kidney, renal vasculature, and surrounding skeletal landmarks; C: Virtual reality–based immersive visualization used for preoperative planning, enabling identification of the posterior lower calyx and simulation of the planned posterior lower calyceal subcostal access tract; D: Intraoperative fluoroscopic image confirming successful posterior lower calyceal puncture corresponding to the preoperatively planned virtual reality trajectory.

Considering the altered renal anatomy, advanced preoperative planning was performed. CECT DICOM images with a 1-mm slice thickness were manually segmented and reconstructed using a VR platform (Figure 1B). VR reconstruction enabled detailed visualisation of the renal axis, pelvicalyceal system, ribs, and adjacent anatomical structures. Interactive assessment of the model enabled a detailed appreciation of the altered calyceal orientation associated with renal malrotation. Based on this evaluation, the posterior lower calyx was identified as the most favourable access point, and a subcostal posterior percutaneous tract was planned to minimise the risk of vascular or visceral injury during PCNL (Figure 1C).

FINAL DIAGNOSIS

Renal pelvic calculus in a malrotated right kidney.

TREATMENT

Standard PCNL was performed with the patient in the prone position under fluoroscopic guidance. A single posterior lower calyceal puncture (Figure 1D) was made through a subcostal access tract, as preoperatively planned using VR guidance. Sequential dilatation was performed up to 24 Fr, and pneumatic lithotripsy was used to fragment and remove the stones.

The operative time was 42 minutes, and the fluoroscopy time was 52 seconds. Blood loss was minimal. Tubeless PCNL was performed, and a 6 Fr/26 cm double-J ureteral stent was placed.

OUTCOME AND FOLLOW-UP

The postoperative course was uneventful. The patient remained haemodynamically stable, with minimal postoperative pain and no evidence of bleeding, fever, or urinary complications. Haemoglobin levels showed only a minimal decrease, and renal function remained within normal limits. As there was no significant bleeding, collecting system perforation, or residual stone burden, a tubeless PCNL approach was adopted, with placement of a 6 Fr/26 cm double-J ureteral stent without nephrostomy tube placement.

The patient recovered well and was mobilised on the first postoperative day. Minimal analgesics were required, and no adverse postoperative events occurred. She was discharged in a stable condition on postoperative day three with advice for routine follow-up.

A non-contrast computed tomography scan at 1 month postoperatively confirmed that the patient was stone-free. The patient has remained asymptomatic since then, with no indications of procedure-related complications.

DISCUSSION

Renal stones greater than 2 cm in size are best treated using PCNL. PCNL has a high success rate and an acceptable morbidity rate[1]. Although the overall success of PCNL depends on many factors, the single most important aspect of the entire procedure is obtaining accurate access to the target collecting system via the percutaneous route. If the initial access site is improperly placed, there are numerous potential complications, including haemorrhage, damage to adjacent intra-abdominal structures, and incomplete removal of the stone burden[2]. Anatomically, the kidneys may have additional complexities owing to the presence of certain anatomical abnormalities. Renal malrotation is a rare congenital renal deformity that occurs when the embryonic kidney does not ascend normally, resulting in an altered configuration of the renal pelvis and calyces[3]. In malrotated kidneys, the renal hilum may lie anteriorly or laterally. Therefore, the use of standard fluoroscopic landmarks to determine the ideal site for percutaneous entry into the collecting system is unreliable, and the likelihood of selecting the correct site is reduced.

VR models generated from computed tomography data allow immersive visualisation of patient-specific anatomy, including the collecting system, renal vasculature, ribs, and adjacent organs. Unlike conventional two-dimensional imaging, VR enables dynamic appreciation of depth and access trajectory, which may assist in preoperative puncture planning in anatomically complex kidneys[4-7]. Previous studies have demonstrated the potential value of three-dimensional reconstruction and VR visualisation in urological surgery, particularly in surgical simulation and preoperative planning[4-7]. Recent studies evaluating mixed-reality and three-dimensional reconstruction technologies in endourology have demonstrated the potential benefits of surgical rehearsal, calyceal orientation recognition, and access planning[6,8-10]. These technologies may become increasingly valuable in cases involving anomalous renal anatomy in which conventional fluoroscopic landmarks are unreliable. A comparison of previously published studies evaluating VR-based surgical planning in urology with the present case is summarised in Table 1.

Table 1 Summary of published studies evaluating virtual reality-based surgical planning in urology and comparison with the present case.

Ref.	Design	VR/3D technology	Clinical context	Key functional advantage	Procedural impact	Clinical relevance
Wake et al[4], 2020	Systematic review	3D printing, AR, VR	General urologic surgery	Enhanced spatial understanding	Not reported	Establishes conceptual framework for 3D/VR utility
Parkhomenko et al[6], 2019	Pilot study	Immersive VR renal models	PCNL planning	Better calyceal orientation recognition	Not reported	Demonstrates feasibility in endourology
Porpiglia et al[5], 2018	Review article	3D virtual models	Preoperative urologic planning	Improved surgical orientation	Not reported	Supports patient-specific planning paradigm
Hosseini et al[8], 2024	Randomized study	3D virtual reconstruction	PCNL access planning	Increased puncture accuracy	Not reported	Provides comparative evidence vs fluoroscopy
Present case, 2026	Case report	Patient-specific immersive VR (CT DICOM-based)	PCNL in malrotated kidney	Precise calyx selection & tract planning	Operative time: 42 minutes. Fluoroscopy: 52 seconds	Demonstrates real-world application in complex anatomy with optimal outcomes

AR: Augmented reality; 3D: Three dimensional; VR: Virtual reality; PCNL: Percutaneous nephrolithotomy; CT: Computed tomography.

In the present case, VR reconstruction clearly identified the altered renal axis and calyceal orientation associated with the malrotated kidney. Through interactive review of the model, the posterior lower calyx was identified as the optimal site for percutaneous entry, and the planned subcostal tract was successfully replicated intraoperatively. This ultimately resulted in successful single-tract PCNL with complete stone clearance and no perioperative complications. Another significant factor was the performance of tubeless PCNL. Tubeless PCNL is considered safe in carefully selected patients who are expected to experience minimal bleeding, have no injury to the collecting system, and undergo complete stone clearance[11]. Therefore, based on these criteria, a nephrostomy tube was not placed, and only a double-J stent was inserted, resulting in faster postoperative recovery. This case highlights the potential role of immersive three-dimensional visualisation as an adjunctive planning tool for PCNL in anatomically complex kidneys. In situations in which conventional fluoroscopic landmarks are unreliable, such as renal malrotation, patient-specific VR reconstruction may assist surgeons in understanding the spatial orientation of the collecting system before entering the operating room. As advanced imaging technologies evolve, VR-assisted surgical planning may become an important component of precision-guided endourological surgery.

Limitations

VR-assisted surgical planning requires specialised software and expertise for image segmentation and reconstruction, thereby limiting the widespread utilisation of this type of planning tool. In addition, operator familiarity with and access to dedicated VR software may further limit widespread implementation. Furthermore, as this is a single-case report, the clinical implications of VR-guided planning on surgical outcomes must be evaluated in larger multicentre studies.

Future directions

As immersive imaging platforms become increasingly accessible, VR-assisted planning may become a practical adjunct to select complex endourological procedures. Potential future applications include integration of VR planning with augmented reality, real-time navigation systems, and robotic assistance to further improve precision in obtaining percutaneous access to the renal collecting system.

CONCLUSION

This case illustrates several clinically significant points regarding the use of advanced imaging modalities to support endourological intervention. Renal malformation alters conventional fluoroscopic anatomy and can complicate percutaneous access during PCNL. Immersive VR reconstruction may assist in preoperative understanding of calyceal orientation and tract planning in anatomically complex kidneys. Further studies are required to evaluate the impact of VR-assisted planning on procedural outcomes and radiation exposure.