Extrarenal Staghorn Stone Migration, a Rare Complication of Percutaneous Nephrolithotomy

Extrarenal Staghorn Stone Migration, a Rare Complication of Percutaneous Nephrolithotomy | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Case Report Extrarenal Staghorn Stone Migration, a Rare Complication of Percutaneous Nephrolithotomy Moath Hattab, Razi Sulaiman, Muhammad Takhman, Fathi Melhem, Mohammad Bdair, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8427939/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Staghorn stones are large branched structures that occupy the renal collecting system, and are usually treated with percutaneous nephrolithotomy (PCNL), this treatment is rarely complicated by extrarenal stone migration, we highlight the diagnostic difficulty in a 36-year-old male that developed extrarenal stone migration and went undiagnosed for 9 months post-PCNL, CT imaging revealed fragments outside the renal collecting system, leading to hydroureteronephrosis and requiring multiple ureteroscopic interventions. We highlight the limitation of x-rays in detecting such complications and emphasize the importance of CT imaging for accurate diagnosis and management, and the role of standardized guidelines in such cases Extrarenal Stone Staghorn Stones Percutaneous Nephrolithotomy Stone Migration Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Highlights • Delayed and missed Diagnosis: Extrarenal stone migration following PCNL can remain undiagnosed for extended periods, complicating patient management. • CT over X-rays: Computed tomography (CT) is superior to X-rays for detecting complications post-PCNL, ensuring timely and accurate diagnosis. • Call for Guidelines: Standardized protocols for postoperative monitoring and management of extrarenal stone migration are necessary to optimize patient outcomes. Introduction Staghorn stones, a large size and branched structure that partially or completely occupy the renal collecting system are considered a therapeutic challenge for healthcare providers, given their propensity for recurrence, association with infections or metabolic disorders, and the technical difficulties involved in their removal. ( 1 ) Staghorn stones have a 5-year recurrence rate of 31.5% to 50% highlighting the importance of choosing the right treatment therapy including surgical procedures and preventive strategies of comprehensive metabolic evaluation, dietary changes, and regular monitoring to reduce recurrence. ( 2 , 3 ) Struvite stones, the primary component of many staghorn calculi, are strongly linked to recurrent infection with urease-producing bacteria. Other risk factors include urinary stasis, congenital urinary tract malformation, distal tubular acidosis, and medullary sponge kidney. ( 3 ) With rising evidence of metabolic staghorn stones being more common than the infectious type as reported by ( 4 ) and ( 5 ) in both studies 73 out of 124 (59%) who underwent percutaneous nephrolithotomy (PNL) and subsequent stone analysis had metabolic stone, complete Laboratory assessment should be done for every patient including complete blood count (CBC), basic metabolic panel (BMP), prothrombin time, serum electrolytes, creatine and parathyroid hormone (PTH) level. ( 1 ) Metabolic abnormalities have been reported and strongly associated with the metabolic type with Hypercalciuria, hypocitraturia and hypernatriuria being the most commonly observed. Several large studies have reported a high prevalence of metabolic abnormalities in patients with staghorn calculi, ranging from 27% to 79%, in populations where infection stones account for 32% to 64% of cases. ( 6 ) Antibiotics are essential for prevention of recurrence and both short and long-term antibiotic therapy is recommended for all patients with staghorn kidney stone. Remarkably, most of urea-splitting bacteria in patient who underwent PCNL were resistant to first- and second-generation cephalosporins highlighting the importance of performing urine culture to ensure the selection of the most effective antibiotic. Other related factors to recurrent staghorn stone are large preoperative stone size, the presence of fragments and other concurrent medical conditions pointing out the importance of repeated imagining and culture to identify recurrence. ( 3 ) We present a case of a 36-year-old male with staghorn stones treated by PCNL and complicated by extrarenal stone migration, and address the challenges in diagnosing such cases and how we managed it. Case Presentation A 36-year-old male with a history of recurrent kidney stones, presented with left flank pain. A computed tomography (CT) scan revealed a large renal calculus resembling a staghorn stone in the left kidney (Fig. 1 ), for which he underwent left Percutaneous Nephrolithotripsy (PCNL), a follow-up x-ray (left scan showed residual stone, therefore the patient underwent 13 sessions of extracorporeal shock wave lithotripsy. Nine months later, the patient presented to our hospital for the first time, repeat triphasic renal CT scan with IV contrast revealed multiple scattered clusters of left sided urinary tract stones following nephrolithotomy. Some of these stones were located within the calyceal system, particularly in the mid and lower calyceal groups, with the largest stone measuring approximately 1.8 × 1.3 cm with a density of 1200 Hounsfield units (HU) in the mid calyceal group. Other stones were identified outside the left collecting system, some located adjacent to the lower renal capsule, near the site of the previous PCNL procedure, consistent with possible injury during the procedure, Larger fragments were found posteromedial to the renal pelvis, collectively measuring approximately 1.9 × 1.8 × 2.7 cm, with a density of approximately 900 HU. Additionally, multiple Ureteral stones were found in the middle and distal segments of the left ureter, measuring up to 8 mm in diameter with a density of about 1300 HU. These stones resulted in moderate upper hydroureteronephrosis and were associated with thickening of the left ureter, primarily in the proximal portion, as well as thickening of the renal pelvis urothelium. Regional fat stranding and a few subcentimetric paraaortic and left iliac lymph nodes in the short axis were noted. A left sided double-J (DJ) stent was noted, from the previous PCNL with its proximal end positioned in the left renal pelvis and its distal end within the bladder. No evidence of contrast leakage or fluid collection was noted. The Fig. 4 shows how the suspected injury happened during the PCNL. The patient underwent multiple flexible ureterorenoscopy (re-fURS) with laser lithotripsy and DJ stent replacement, multiple operations were needed due to blockage of the ureter with multiple small stone fragments, possibly from the shockwave therapy and due to limited laser time in each operation, The preoperative laboratory tests were unremarkable, showing normal serum creatinine and blood urea nitrogen (BUN) levels. The previous left DJ stent was heavily encrusted and embedded in the left ureter, along with numerous ureteral stones. The procedure was completed without complications (Fig. 5 ), and the postoperative course was uneventful. The patient was discharged in stable clinical condition and scheduled for multiple sessions of flexible ureterorenoscopy with laser lithotripsy to manage the ureteral stones. Discussion Extrarenal migration of stone fragments is a rare, serious complication of PCNL treatment for staghorn stones ( 7 ). The case presented is a rare occurrence of extrarenal stone migration after PCNL, where fragments of the staghorn stone escaped the renal collecting system and remained undiagnosed for a period of over nine months. Not even asymptomatic, despite late presentation, has raised concerns regarding the most appropriate or timely intervention. The delayment of the diagnosis highlighted the inadequacy or insensitivity of X-ray with respect to follow-up checks after the operation and made it important to stress diagnostic advantages of CT in general for the detection of described complications. This case continues ongoing review intended upon enlightening postoperative management and pointing out better ways of monitoring such unusual PCNL outcomes. It emerged more than three decades ago to attain the status and is considered the standard minimally invasive procedure for treating large and complex renal calculi, including staghorn and lower pole calculi ( 8 ). Success in PCNL is dependent on the direct access that it provides to the renal collecting system, where effective fragmentation and removal are accomplished. Superior SFRs have been reported, from 40% to 90%, depending on several factors like stone size, anatomical complexity, and expertise of the surgical team ( 9 ). Compared to other alternative techniques such as SWL and URS, PCNL has always kept a nose in front concerning success rates, especially for more considerable stone burdens. The recent advances in the surgical technology of miniaturization of instruments such as micro-PCNL, with improved imaging techniques like real-time ultrasound and fluoroscopy, have greatly enhanced the safety and efficacy of PCNL ( 10 , 11 ). Refinements in the surgical approach, such as the tubeless technique, have dramatically shortened the recovery period, reduced hospital stay, and minimized complications. These have secured the position of PCNL as a first-line treatment modality for complex renal calculi, keeping it quite relevant in modern urology ( 12 ). In spite of these advances, intraoperative and postoperative complications remain a critical issue that often influences the outcome of the patients. Among them, one of the most rare but important complications is extrarenal stone migration ( 13 ). This includes stone fragments migrating out of the renal collecting system into surrounding tissues or organs, thus being both diagnostic and therapeutic challenges ( 11 ). Our case underlines the need for early detection and appropriate management of such complications. Akbulut et al. (2015) reported a case of upper calyceal perforation with infrahepatic migration of stone fragments after Micro-PCNL in a 20-year-old female. This complication, due to increased intrapelvic pressure, resulted in the formation of a perirenal urinoma and residual fragments ( 14 ). Early termination of the procedure was required, and a subsequent definitive surgery successfully resolved the issue with no long-term complications ( 15 ). Baytok and Ecer (2024) reported another case in which a 7-mm stone migrated to the psoas major muscle laterally in a 43-year-old man after PNL and retrograde intrarenal surgery ( 16 ). It was conservatively managed as the patient was asymptomatic, again a support for the various nonsurgical options if the conditions allow for them. Further studies have also illuminated both complications and better management strategies. A systematic review by Nabhani et al. (2017) pointed to preoperative planning, inclusive of metabolic assessment and individually appropriate surgical technique, in reduction of complications ( 17 ). they observed that, through adequate hydration and optimization nutritional support, enhanced recovery pathway ensures significant improvements in results. Gadzhiev et al. (2020) also supported low-pressure irrigation system and adequate intra-operatively drainage for the prevention of a minimal risk of extra renal migration ( 7 ). A large retrospective analysis by Zeng et al. (2022) has emphasized the role of advanced imaging modalities in postoperative care. Among these, CT scans afford more precise evaluation of residual stones, thus guiding further intervention ( 18 ). Similarly, Kingma et al. (2019) have shown that the introduction of three-dimensional imaging systems enhances the accuracy of stone clearance assessment and decreases the rates of secondary procedures, focusing on the role of advanced technologies in the management of PCNL ( 19 ). Conclusion Our case, in amalgamation with the above studies, emphasizes an individualized approach to treatment in the management of PCNL. Advanced imaging, such as three-dimensional CT, provides more informed surgical planning and postoperative follow-up ( 20 ). ERAS protocol evidence from Lei et al. also improves the outcomes if combined with close monitoring and patient-specific strategies ( 21 ). These developments underline the fact that a holistic approach is thus imperative in complication management and optimization of patient care ( 22 ). Delayed presentation of extrarenal stones in our case further points out the shortcomings of X-rays in diagnosing the complications after PCNL. With their low specificity, diagnoses based on X-rays only might miss a diagnosis. CT is to be considered the standard gold postoperative imaging in PCNL patients, especially where symptoms persist or complications are suspected ( 23 ). Finally, our case adds to the growing evidence supporting the importance of developing standardized guidelines regarding the timing and management of asymptomatic extrarenal stone migrations. A decision to operate should be made by balancing the risks of surgical intervention against the potential for spontaneous resolution or conservative management. Declarations Ethics approval and consent to participate Our institution doesn’t require ethical approval for case reports. Consent for publication The patient provided written informed consent for the publication of this case report and accompanying images. The editor-in-chief of this journal can review a copy of the consent on request. Funding All Authors have no source of funding. Acknowledgment We express our deep gratitude to the medical ward staff for their invaluable support in completing this report. Clinical Trial registration No trial registry number. Conflict of interest statement All Authors have no conflict of interest. References Sharbaugh A, Morgan Nikonow T, Kunkel G, Semins MJ. Contemporary best practice in the management of staghorn calculi. Ther Adv Urol. 2019;11:1756287219847099. 10.1177/1756287219847099 . PMID: 35173810; PMCID: PMC8842174. Lei J, Huang K, Dai Y, Yin G. Evaluating outcomes of patient-centered enhanced recovery after surgery (ERAS) in percutaneous nephrolithotomy for staghorn stones: An initial experience. Front Surg. 2023;10:1138814. 10.3389/fsurg.2023.1138814 . PMID: 37025266; PMCID: PMC10071039. Torricelli FCM, Monga M. Staghorn renal stones: what the urologist needs to know. Int Braz J Urol. 2020 Nov-Dec;46(6):927–33. 10.1590/S1677-5538.IBJU.2020.99.07 . PMID: 32213203; PMCID: PMC7527092. 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Nephropleural fistula after supracostal approach for PCNL: report of two cases with review of literature. 2021;14(4):e241360. Baytok A, Ecer GJIJN, Sciences L. Extrarenal Stone Migration After PNL and RIRS: Effectiveness of Conservative Follow-up in Light of Literature.8(2):204 – 10. Kerr PS, Williams SBJRS. Enhanced Recovery After Surgery (ERAS) in Urology: Where Do We Go From Here? 2021:1189 – 200. Zeng G, Zhong W, Pearle M, Choong S, Chew B, Skolarikos A et al. European association of urology section of urolithiasis and international alliance of urolithiasis joint consensus on percutaneous nephrolithotomy. 2022;8(2):588–97. Kingma R, Voskamp M, Doornweerd BH, de Jong I, Roemeling SJU. Intraoperative cone beam computed tomography for detecting residual stones in percutaneous nephrolithotomy: a feasibility study. 2021:1–7. Al-Haj Husain A, Stadlinger B, Winklhofer S, Bosshard FA, Schmidt V, Valdec SJJCM. Imaging in third molar surgery: a clinical update. 2023;12(24):7688. Lei J, Huang K, Dai Y, Yin GJFS. Evaluating outcomes of patient-centered enhanced recovery after surgery (ERAS) in percutaneous nephrolithotomy for staghorn stones: an initial experience. 2023;10:1138814. Falade IM, Gyampoh GKS, Akpamgbo EO, Chika OC, Obodo OR, Okobi OE et al. Compr Rev Effective Patient Saf Qual Improv Programs Healthc Facilities. 2024;12(7). Ngoo K-S, Sothilingam SJPMUS. Imaging for urinary calculi. 2021:11–24.). Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8427939","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Case Report","associatedPublications":[],"authors":[{"id":578162972,"identity":"e43329a7-abf5-445f-b08b-88e1702d3adf","order_by":0,"name":"Moath 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16:06:09","extension":"xml","order_by":13,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":53601,"visible":true,"origin":"","legend":"","description":"","filename":"7530b21c3915415bbcdd72bd6c383ceb1structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-8427939/v1/69b58f8f9753161bef5f58e2.xml"},{"id":100906849,"identity":"761b7b48-2d0a-4412-82ce-fd7434635181","added_by":"auto","created_at":"2026-01-22 16:06:09","extension":"html","order_by":14,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":63078,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-8427939/v1/358abeb8392df63bb994830c.html"},{"id":100906838,"identity":"f1256abf-423a-4e63-bd25-4db1846b0a03","added_by":"auto","created_at":"2026-01-22 16:06:09","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":579581,"visible":true,"origin":"","legend":"\u003cp\u003eInitial abdominal CT showing a Staghorn stone (yellow arrow) in the left kidney on thick slice. (A: Coronal View, B: Sagittal View, C: Oblique)\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-8427939/v1/c5d5644ad7cc78bdedc4263d.png"},{"id":100951817,"identity":"9067577b-d7c1-4192-a475-95ad62f14762","added_by":"auto","created_at":"2026-01-23 07:11:17","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1166733,"visible":true,"origin":"","legend":"\u003cp\u003eAbdominal x-rays showing an extrarenal stone, at 2 weeks day after surgery (A) and 9 months later (B), initially it wasn’t suspected as extrarenal, but only thought to be residual stone.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-8427939/v1/03d709127b959664d5aed212.png"},{"id":100951705,"identity":"8f3d46e2-c860-40f9-bce9-a5873108be1b","added_by":"auto","created_at":"2026-01-23 07:11:06","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":590202,"visible":true,"origin":"","legend":"\u003cp\u003eSecond abdominal CT showing an extrarenal stone outside the left kidney (yellow arrow), measuring 2.6x1.6x1.6, taken 9 months after initial PCNL (A: Coronal View, B: Sagittal View, C: Oblique).\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-8427939/v1/da6410aa0733556a2edf1c27.png"},{"id":100906839,"identity":"4f2203e7-e384-497f-8d2e-14da83ccce3d","added_by":"auto","created_at":"2026-01-22 16:06:09","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":359999,"visible":true,"origin":"","legend":"\u003cp\u003edepicting PCNL procedure (A) and post-PCNL complications in a patient with residual stones, extrarenal migration, and ureteral obstruction (B). The figure shows anatomical diagram of the left kidney, highlighting the locations of residual stones in the calyceal system and larger fragments that have migrated extrarenally, near the renal capsule and posteromedial to the renal pelvis. The figure also illustrates multiple ureteral stones causing moderate hydroureteronephrosis and thickening of the ureter. This diagram emphasizes the importance of accurate postoperative monitoring in managing complications following PCNL.\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-8427939/v1/149f0951382cc1f8e83203a5.png"},{"id":100951015,"identity":"b8dd242b-b4d9-49a6-a43d-5b8f8e64694d","added_by":"auto","created_at":"2026-01-23 07:09:50","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":1157689,"visible":true,"origin":"","legend":"\u003cp\u003eRetrograde pyelogram taken during the flexible ureteroscope showing a stone outside the kidney (A: Before DJ Stent Insertion, B: after DJ Stent Insertion).\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-8427939/v1/8a637a08ee4777e1bf9a522d.png"},{"id":105028876,"identity":"4d344e68-14cf-4256-85ad-e282592304eb","added_by":"auto","created_at":"2026-03-20 05:56:01","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4072099,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8427939/v1/2a229652-8092-4ae1-b0bb-275b9d02af16.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Extrarenal Staghorn Stone Migration, a Rare Complication of Percutaneous Nephrolithotomy","fulltext":[{"header":"Highlights","content":"\u003cp\u003e\u0026bull; Delayed and missed Diagnosis: Extrarenal stone migration following PCNL can remain undiagnosed for extended periods, complicating patient management.\u003c/p\u003e\u003cp\u003e\u0026bull; CT over X-rays: Computed tomography (CT) is superior to X-rays for detecting complications post-PCNL, ensuring timely and accurate diagnosis.\u003c/p\u003e\u003cp\u003e\u0026bull; Call for Guidelines: Standardized protocols for postoperative monitoring and management of extrarenal stone migration are necessary to optimize patient outcomes.\u003c/p\u003e"},{"header":"Introduction","content":"\u003cp\u003eStaghorn stones, a large size and branched structure that partially or completely occupy the renal collecting system are considered a therapeutic challenge for healthcare providers, given their propensity for recurrence, association with infections or metabolic disorders, and the technical difficulties involved in their removal. (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e)\u003c/p\u003e \u003cp\u003eStaghorn stones have a 5-year recurrence rate of 31.5% to 50% highlighting the importance of choosing the right treatment therapy including surgical procedures and preventive strategies of comprehensive metabolic evaluation, dietary changes, and regular monitoring to reduce recurrence. (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e) Struvite stones, the primary component of many staghorn calculi, are strongly linked to recurrent infection with urease-producing bacteria. Other risk factors include urinary stasis, congenital urinary tract malformation, distal tubular acidosis, and medullary sponge kidney. (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e) With rising evidence of metabolic staghorn stones being more common than the infectious type as reported by (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e) and (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e) in both studies 73 out of 124 (59%) who underwent percutaneous nephrolithotomy (PNL) and subsequent stone analysis had metabolic stone, complete Laboratory assessment should be done for every patient including complete blood count (CBC), basic metabolic panel (BMP), prothrombin time, serum electrolytes, creatine and parathyroid hormone (PTH) level. (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e) Metabolic abnormalities have been reported and strongly associated with the metabolic type with Hypercalciuria, hypocitraturia and hypernatriuria being the most commonly observed. Several large studies have reported a high prevalence of metabolic abnormalities in patients with staghorn calculi, ranging from 27% to 79%, in populations where infection stones account for 32% to 64% of cases. (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e) Antibiotics are essential for prevention of recurrence and both short and long-term antibiotic therapy is recommended for all patients with staghorn kidney stone. Remarkably, most of urea-splitting bacteria in patient who underwent PCNL were resistant to first- and second-generation cephalosporins highlighting the importance of performing urine culture to ensure the selection of the most effective antibiotic. Other related factors to recurrent staghorn stone are large preoperative stone size, the presence of fragments and other concurrent medical conditions pointing out the importance of repeated imagining and culture to identify recurrence. (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e)\u003c/p\u003e \u003cp\u003eWe present a case of a 36-year-old male with staghorn stones treated by PCNL and complicated by extrarenal stone migration, and address the challenges in diagnosing such cases and how we managed it.\u003c/p\u003e"},{"header":"Case Presentation","content":"\u003cp\u003eA 36-year-old male with a history of recurrent kidney stones, presented with left flank pain. A computed tomography (CT) scan revealed a large renal calculus resembling a staghorn stone in the left kidney (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), for which he underwent left Percutaneous Nephrolithotripsy (PCNL), a follow-up x-ray (left scan showed residual stone, therefore the patient underwent 13 sessions of extracorporeal shock wave lithotripsy.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eNine months later, the patient presented to our hospital for the first time, repeat triphasic renal CT scan with IV contrast revealed multiple scattered clusters of left sided urinary tract stones following nephrolithotomy. Some of these stones were located within the calyceal system, particularly in the mid and lower calyceal groups, with the largest stone measuring approximately 1.8 \u0026times; 1.3 cm with a density of 1200 Hounsfield units (HU) in the mid calyceal group. Other stones were identified outside the left collecting system, some located adjacent to the lower renal capsule, near the site of the previous PCNL procedure, consistent with possible injury during the procedure, Larger fragments were found posteromedial to the renal pelvis, collectively measuring approximately 1.9 \u0026times; 1.8 \u0026times; 2.7 cm, with a density of approximately 900 HU. Additionally, multiple Ureteral stones were found in the middle and distal segments of the left ureter, measuring up to 8 mm in diameter with a density of about 1300 HU. These stones resulted in moderate upper hydroureteronephrosis and were associated with thickening of the left ureter, primarily in the proximal portion, as well as thickening of the renal pelvis urothelium. Regional fat stranding and a few subcentimetric paraaortic and left iliac lymph nodes in the short axis were noted. A left sided double-J (DJ) stent was noted, from the previous PCNL with its proximal end positioned in the left renal pelvis and its distal end within the bladder. No evidence of contrast leakage or fluid collection was noted. The Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e shows how the suspected injury happened during the PCNL.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe patient underwent multiple flexible ureterorenoscopy (re-fURS) with laser lithotripsy and DJ stent replacement, multiple operations were needed due to blockage of the ureter with multiple small stone fragments, possibly from the shockwave therapy and due to limited laser time in each operation, The preoperative laboratory tests were unremarkable, showing normal serum creatinine and blood urea nitrogen (BUN) levels. The previous left DJ stent was heavily encrusted and embedded in the left ureter, along with numerous ureteral stones. The procedure was completed without complications (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e), and the postoperative course was uneventful. The patient was discharged in stable clinical condition and scheduled for multiple sessions of flexible ureterorenoscopy with laser lithotripsy to manage the ureteral stones.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eExtrarenal migration of stone fragments is a rare, serious complication of PCNL treatment for staghorn stones (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e). The case presented is a rare occurrence of extrarenal stone migration after PCNL, where fragments of the staghorn stone escaped the renal collecting system and remained undiagnosed for a period of over nine months. Not even asymptomatic, despite late presentation, has raised concerns regarding the most appropriate or timely intervention. The delayment of the diagnosis highlighted the inadequacy or insensitivity of X-ray with respect to follow-up checks after the operation and made it important to stress diagnostic advantages of CT in general for the detection of described complications. This case continues ongoing review intended upon enlightening postoperative management and pointing out better ways of monitoring such unusual PCNL outcomes.\u003c/p\u003e \u003cp\u003eIt emerged more than three decades ago to attain the status and is considered the standard minimally invasive procedure for treating large and complex renal calculi, including staghorn and lower pole calculi (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e). Success in PCNL is dependent on the direct access that it provides to the renal collecting system, where effective fragmentation and removal are accomplished. Superior SFRs have been reported, from 40% to 90%, depending on several factors like stone size, anatomical complexity, and expertise of the surgical team (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). Compared to other alternative techniques such as SWL and URS, PCNL has always kept a nose in front concerning success rates, especially for more considerable stone burdens. The recent advances in the surgical technology of miniaturization of instruments such as micro-PCNL, with improved imaging techniques like real-time ultrasound and fluoroscopy, have greatly enhanced the safety and efficacy of PCNL (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e). Refinements in the surgical approach, such as the tubeless technique, have dramatically shortened the recovery period, reduced hospital stay, and minimized complications. These have secured the position of PCNL as a first-line treatment modality for complex renal calculi, keeping it quite relevant in modern urology (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn spite of these advances, intraoperative and postoperative complications remain a critical issue that often influences the outcome of the patients. Among them, one of the most rare but important complications is extrarenal stone migration (\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e). This includes stone fragments migrating out of the renal collecting system into surrounding tissues or organs, thus being both diagnostic and therapeutic challenges (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e). Our case underlines the need for early detection and appropriate management of such complications.\u003c/p\u003e \u003cp\u003eAkbulut et al. (2015) reported a case of upper calyceal perforation with infrahepatic migration of stone fragments after Micro-PCNL in a 20-year-old female. This complication, due to increased intrapelvic pressure, resulted in the formation of a perirenal urinoma and residual fragments (\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e). Early termination of the procedure was required, and a subsequent definitive surgery successfully resolved the issue with no long-term complications (\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e). Baytok and Ecer (2024) reported another case in which a 7-mm stone migrated to the psoas major muscle laterally in a 43-year-old man after PNL and retrograde intrarenal surgery (\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e). It was conservatively managed as the patient was asymptomatic, again a support for the various nonsurgical options if the conditions allow for them.\u003c/p\u003e \u003cp\u003eFurther studies have also illuminated both complications and better management strategies. A systematic review by Nabhani et al. (2017) pointed to preoperative planning, inclusive of metabolic assessment and individually appropriate surgical technique, in reduction of complications (\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e). they observed that, through adequate hydration and optimization nutritional support, enhanced recovery pathway ensures significant improvements in results. Gadzhiev et al. (2020) also supported low-pressure irrigation system and adequate intra-operatively drainage for the prevention of a minimal risk of extra renal migration (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e). A large retrospective analysis by Zeng et al. (2022) has emphasized the role of advanced imaging modalities in postoperative care. Among these, CT scans afford more precise evaluation of residual stones, thus guiding further intervention (\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e). Similarly, \u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eKingma\u003c/span\u003e et al. (2019) have shown that the introduction of three-dimensional imaging systems enhances the accuracy of stone clearance assessment and decreases the rates of secondary procedures, focusing on the role of advanced technologies in the management of PCNL (\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e).\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eOur case, in amalgamation with the above studies, emphasizes an individualized approach to treatment in the management of PCNL. Advanced imaging, such as three-dimensional CT, provides more informed surgical planning and postoperative follow-up (\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e). ERAS protocol evidence from Lei et al. also improves the outcomes if combined with close monitoring and patient-specific strategies (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e). These developments underline the fact that a holistic approach is thus imperative in complication management and optimization of patient care (\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e). Delayed presentation of extrarenal stones in our case further points out the shortcomings of X-rays in diagnosing the complications after PCNL. With their low specificity, diagnoses based on X-rays only might miss a diagnosis. CT is to be considered the standard gold postoperative imaging in PCNL patients, especially where symptoms persist or complications are suspected (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFinally, our case adds to the growing evidence supporting the importance of developing standardized guidelines regarding the timing and management of asymptomatic extrarenal stone migrations. A decision to operate should be made by balancing the risks of surgical intervention against the potential for spontaneous resolution or conservative management.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eOur institution doesn\u0026rsquo;t require ethical approval for case reports.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe patient provided written informed consent for the publication of this case report and accompanying images. The editor-in-chief of this journal can review a copy of the consent on request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll Authors have no source of funding.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgment\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe express our deep gratitude to the medical ward staff for their invaluable support in completing this report.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eClinical Trial registration\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo trial registry number.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of interest statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll Authors have no conflict of interest.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eSharbaugh A, Morgan Nikonow T, Kunkel G, Semins MJ. Contemporary best practice in the management of staghorn calculi. 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Imaging for urinary calculi. 2021:11\u0026ndash;24.).\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Extrarenal Stone, Staghorn Stones, Percutaneous Nephrolithotomy, Stone Migration","lastPublishedDoi":"10.21203/rs.3.rs-8427939/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8427939/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eStaghorn stones are large branched structures that occupy the renal collecting system, and are usually treated with percutaneous nephrolithotomy (PCNL), this treatment is rarely complicated by extrarenal stone migration, we highlight the diagnostic difficulty in a 36-year-old male that developed extrarenal stone migration and went undiagnosed for 9 months post-PCNL, CT imaging revealed fragments outside the renal collecting system, leading to hydroureteronephrosis and requiring multiple ureteroscopic interventions. We highlight the limitation of x-rays in detecting such complications and emphasize the importance of CT imaging for accurate diagnosis and management, and the role of standardized guidelines in such cases\u003c/p\u003e","manuscriptTitle":"Extrarenal Staghorn Stone Migration, a Rare Complication of Percutaneous Nephrolithotomy","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-01-22 16:06:03","doi":"10.21203/rs.3.rs-8427939/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"fecb3a19-7c08-400d-a7ec-4e808f6f1770","owner":[],"postedDate":"January 22nd, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-03-20T05:55:30+00:00","versionOfRecord":[],"versionCreatedAt":"2026-01-22 16:06:03","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8427939","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8427939","identity":"rs-8427939","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}