Embolization of a Large Arteriovenous Fistula in a Transplanted Kidney: A Case Report

Embolization of a Large Arteriovenous Fistula in a Transplanted Kidney: A Case Report | 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 Embolization of a Large Arteriovenous Fistula in a Transplanted Kidney: A Case Report Houmam Qassab, Anthony Esswein, Maaz Ghouri, Islam Elhelf This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9500905/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 Background: Arteriovenous fistulas of transplanted kidneys are uncommon but potentially serious vascular complications, most often occurring after biopsy or surgical trauma. While many are small and resolve spontaneously, large fistulas can cause persistent hematuria, graft dysfunction, and hemodynamic compromise. Early recognition is critical, as delayed diagnosis may lead to significant morbidity or unnecessary graft loss. This case highlights the evolution of a large transplant-kidney arteriovenous fistula and demonstrates successful minimally invasive management using endovascular coil embolization. Case presentation: A 56-year-old male with a history of end-stage renal disease on hemodialysis and prior kidney transplantation presented with persistent hematuria and altered mental status. Initial computed tomography of the abdomen and pelvis revealed diffuse enlargement of the transplanted kidney with loss of normal corticomedullary differentiation, concerning for lymphoproliferative disease, along with a pseudoaneurysm. Conservative management was initially pursued. Due to ongoing hematuria, repeat computed tomography angiography demonstrated a markedly enlarged vascular structure within the transplant kidney with early venous opacification, consistent with a large arteriovenous fistula. Interventional radiology performed endovascular embolization via femoral artery access. Selective catheterization identified anterior and posterior renal arterial feeders, which were successfully occluded using a combination of detachable coils. Completion angiography confirmed complete occlusion of the fistula with preservation of the main renal arterial flow. Post-procedural ultrasound and follow-up computed tomography angiography showed no residual flow. Conclusions: This case demonstrates that large arteriovenous fistulas in transplanted kidneys can develop and progress during hospitalization and should be considered in patients with persistent hematuria. Endovascular coil embolization is a safe and effective treatment that allows for targeted occlusion of the fistula while preserving renal perfusion. Early diagnosis and minimally invasive intervention can prevent complications and may avoid the need for surgical graft removal. Arteriovenous fistula Kidney transplant Embolization Interventional radiology Pseudoaneurysm Renal vascular complication Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Background Arteriovenous fistulas (AVFs) are rare but serious complications in transplant kidneys, with an estimated incidence of 6–8% in kidney transplant recipients. AVFs in a transplant setting usually result from trauma, biopsy procedures, or inadvertent surgical complications. Although most are small and resolve spontaneously, larger AVFs can lead to hematuria, kidney dysfunction, and eventually high-output heart failure due to volume overload. Transcatheter embolization is the preferred management technique for larger or symptomatic AVFs due to its efficacy and kidney-sparing nature. We report a case of a large transplant-kidney AVF successfully treated with coil embolization, emphasizing the imaging evolution, interventional approach, and clinical outcome. Case Presentation A 56-year-old male with a history of end-stage renal disease (ESRD) on hemodialysis, kidney transplant in 2015, hypertension, diabetes, and heart failure, presented with complaints of altered mental status, hematuria, and confusion. The patient was empirically started on Vancomycin and Zosyn, transfused one unit of blood for anemia, and admitted to the intermediate care unit for sepsis workup. On the third day of hospitalization, a contrasted CT of the abdomen and pelvis was performed to evaluate for possible malignancy due to persistent hematuria. The CT revealed diffuse enlargement of the right transplant kidney with loss of normal corticomedullary differentiation, concerning for lymphoproliferative disease. Additionally, a pseudoaneurysm was noted in the superior medial aspect of the transplant kidney, measuring 1.4 x 2.2 x 1.6 cm (Fig. 1 ). An ultrasound of the transplant kidney was also ordered which showed increased echogenicity with a “yin-yang” sign, consistent with turbulent flow (Fig. 2 ). At that time, embolization was suggested to the transplant service but was not agreed upon as they expected to explant the kidney due to lymphoproliferative disorder. Over the next two weeks, the patient's hematuria persisted, prompting further evaluation. A repeat CTA of the abdomen and pelvis revealed a significantly enlarged tubular vascular structure within the transplant kidney measuring 70.5 × 24.2 mm (Fig. 3 a), with early venous opacification of the right common iliac vein during the arterial phase (Fig. 3 b), findings strongly suggestive of a large AVF. No active bleeding or peritransplant hematoma was identified. Given the size of the AVF and ongoing symptoms, interventional radiology was consulted for endovascular treatment. Endovascular Procedure: Using ultrasound-guided retrograde right common femoral artery access, a 5 Fr × 10 cm sheath was placed. A diagnostic angiogram performed via a 5 Fr Glide catheter confirmed a large AVF in the superior portion of the transplant kidney, supplied by both anterior and posterior branches of the transplant renal artery (Figs. 4 a,b,c). Selective microcatheterization was performed with a Lantern microcatheter to target each feeding vessel: Anterior renal artery: occluded with one POD3 20 cm coil and one 4 mm × 10 cm Ruby coil (Fig. 5 a). Posterior renal artery: occluded with Azur 6 mm × 17 cm, 5 mm × 11 cm, and 4 mm × 7 cm coils (Fig. 5 b). Figure 5 a. Embolization of the anterior renal-artery feeder using a POD3 20 cm coil (red arrow) and a 4 mm × 10 cm Ruby coil (blue arrow). Sequential angiograms demonstrated progressive reduction and then complete cessation of flow through the fistula. Final angiography showed total occlusion of the AVF with preservation of the main renal artery flow (Fig. 6 a,b). The puncture site was closed using an Angio-Seal device. Estimated blood loss was < 10 mL. The patient remained hemodynamically stable throughout. Post-Procedure Course: The patient’s hematuria subsided within 24 hours. A post-procedure Doppler ultrasound confirmed absence of flow within the embolized AVF (Fig. 7 ). He was maintained on bed rest for four hours. A follow-up CTA abdomen and pelvis four days later (Figs. 8 a and 8 b) demonstrated no residual aneurysm, fistula, or active contrast extravasation, confirming durable occlusion. The patient was in stable condition, with complete resolution of hematuria and preserved graft perfusion. Conclusion Arteriovenous fistulas (AVFs) are abnormal connections between arteries and veins, bypassing the normal capillary network. In transplant kidneys, these AVFs can occur due to surgical trauma, biopsy procedures, or other post-operative complications. A large AVF permits arterial blood to bypass the high-resistance capillary network, causing a fall in systemic vascular resistance. To maintain perfusion, stroke volume, heart rate, and cardiac output increase. Sustained shunting increases venous return, resulting in ventricular dilation, left-ventricular hypertrophy, and eventual high-output failure. Locally, continuous shunting may lead to renal ischemia, pseudoaneurysm formation, and graft dysfunction. Color Doppler ultrasound is the initial modality of choice, demonstrating turbulent bidirectional flow (“yin-yang” sign) and spectral broadening. CT angiography provides detailed vascular anatomy, defining the feeding artery, draining vein, and associated pseudoaneurysm. Interventional radiology offers a minimally invasive method for treating AVFs in renal transplant recipients. Embolization using coils is considered the gold standard, as it directly occludes the feeding arteries, preventing further blood flow through the fistula. Coils, such as POD3, Ruby, and Azur, were used in this case to effectively occlude the feeding vessels. Embolization is typically preferred over surgical interventions due to its minimally invasive nature, reduced complication rates, and shorter recovery times. The use of microcatheters for selective cannulation allows for precise embolization and effective management of the AVF. The success of embolization is confirmed by post-procedural imaging, including angiography and ultrasound. In this case, both the angiogram and ultrasound demonstrated no residual blood flow, indicating complete occlusion of the AVF. Long-term outcomes are excellent, with most patients demonstrating complete resolution of hematuria and stable graft function. Our patient remained asymptomatic with no evidence of residual AVF or pseudoaneurysm on follow-up CTA. This case reinforces the crucial role of interventional radiology in diagnosing and managing vascular complications of renal transplantation. Early recognition and minimally invasive therapy prevent progression to heart failure or graft loss while minimizing patient morbidity. Declarations Ethics approval and consent to participate: This study involves a single patient case report. Ethical approval was not required in accordance with institutional guidelines. Consent for publication: Written informed consent was obtained from the patient for publication of this case report and any accompanying images. Funding: The authors received no specific funding for this work. Acknowledgements: Not applicable. Authors’ information: Not applicable. Author Contribution I.E., M.G., A.E. managed the patient. H.Q. and A.E. performed the literature review and drafted the manuscript. All authors read and approved the final version. Availability of data and materials: All data generated or analyzed during this study are included in this published article. Additional information is available from the corresponding author on reasonable request. Competing interests: The authors declare that they have no competing interests. References Vij G, Hamper UM, De Jong MR, Scoutt LM. A pot pourri of abdominal Doppler cases. Ultrasound Clin . 2011; 6(4):531–550. doi: 10.1016/j.cult.2011.07.005 . Crotty KL, Orihuela E, Warren MM. Recent advances in the diagnosis and treatment of renal arteriovenous malformations and fistulas. J Urol . 1993; 150(5 Pt 1):1355–1359. doi: 10.1016/S0022-5347(17)35778-6 . Nagpal P, Bathla G, Saboo SS, et al. Giant idiopathic renal arteriovenous fistula managed by coils and Amplatzer device: Case report and literature review. World J Clin Cases . 2016; 4(11):364–368. doi: 10.12998/wjcc.v4.i11.364 . Tynes WV, Devine CJ, Devine PC, Poutasse EF. Surgical treatment of renal arteriovenous fistulas: Report of 5 cases. J Urol [Internet]. 1970 Jun 1 [cited 2025 Nov 4]; 103(6):692–698. Available from: https://doi.org/10.1016/S0022-5347(17)62029-9 . Fogazzi GB, Moriggi M, Fontanella U. Spontaneous renal arteriovenous fistula as a cause of haematuria. Nephrol Dial Transplant . 1997; 12(2):350–356. doi: 10.1093/ndt/12.2.350 . Duc VT, Duong NQT, Phong NT, Nam NH, Quoc DA, Cuong TTQ, Huy NH, Duy TL, Chien PC. Large renal arteriovenous fistula treated by embolization: A case report. Radiol Case Rep . 2021; 16(8):2289–2294. doi: 10.1016/j.radcr.2021.05.058 . 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. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-9500905","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Case Report","associatedPublications":[],"authors":[{"id":637825020,"identity":"2ee3a8f2-a877-4094-9d72-dbfe11dbb737","order_by":0,"name":"Houmam Qassab","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA3ElEQVRIiWNgGAWjYBACAwh1QA5JLIE4LcZIqonUkthAtBZz9uTHH3/U3Envn5F+TfLnDzsGfvYcA7xaLHuemUnzHHuWO+NGTpk0T0Iyg2TPG/xaDG4kmDEzsB3ObbiRkybNkMAMFCFgi8GN9M8ff/w7nC4P1CL5I6GewZ6wlhwDCd62wwlAvcckeBIOMxhIENJy5k2ZNG/fM8ONZ94wW/OkHeeROPOsAL+W4+mbP/74dkde7nj6w5s/bKrl+NuTN+DVghQLPGD38BBQjqKF/QERqkfBKBgFo2AkAgBmkk0GTxk2YAAAAABJRU5ErkJggg==","orcid":"","institution":"Medical College of Georgia","correspondingAuthor":true,"prefix":"","firstName":"Houmam","middleName":"","lastName":"Qassab","suffix":""},{"id":637825021,"identity":"060e3734-12ce-41e5-b88a-f6fb79cdf597","order_by":1,"name":"Anthony Esswein","email":"","orcid":"","institution":"Medical College of Georgia","correspondingAuthor":false,"prefix":"","firstName":"Anthony","middleName":"","lastName":"Esswein","suffix":""},{"id":637825022,"identity":"b2b05dd1-53dc-4034-83d9-938b5323bf4a","order_by":2,"name":"Maaz Ghouri","email":"","orcid":"","institution":"Wellstar Medical Group","correspondingAuthor":false,"prefix":"","firstName":"Maaz","middleName":"","lastName":"Ghouri","suffix":""},{"id":637825023,"identity":"c6182f20-185b-41d8-81a6-f02c2c57b8ca","order_by":3,"name":"Islam Elhelf","email":"","orcid":"","institution":"Augusta University","correspondingAuthor":false,"prefix":"","firstName":"Islam","middleName":"","lastName":"Elhelf","suffix":""}],"badges":[],"createdAt":"2026-04-23 00:54:25","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9500905/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9500905/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":109150410,"identity":"26bde214-c790-4a2f-87b8-6ea594e3d7e5","added_by":"auto","created_at":"2026-05-13 05:28:22","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":93233,"visible":true,"origin":"","legend":"\u003cp\u003eFigure 1. CTA abdomen/pelvis showing diffuse enlargement of the right transplant kidney with a 1.4 × 2.2 × 1.6 cm superior-medial pole pseudoaneurysm (arrow).\u003c/p\u003e","description":"","filename":"Picture1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9500905/v1/baab15887da63aa9e127aa53.jpg"},{"id":109150411,"identity":"23de5821-d856-42a9-8c5a-36bd7b194cad","added_by":"auto","created_at":"2026-05-13 05:28:23","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":14905,"visible":true,"origin":"","legend":"\u003cp\u003eFigure 2. Doppler ultrasound of the transplant kidney demonstrating the classic “yin-yang” sign (arrow) of turbulent bidirectional flow within the pseudoaneurysm.\u003c/p\u003e","description":"","filename":"Picture2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9500905/v1/f0fbd24ce84bbc6a0bf05ad2.jpg"},{"id":109150398,"identity":"8ef9df5c-a243-4940-b48c-0dad08d4d310","added_by":"auto","created_at":"2026-05-13 05:28:20","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":102999,"visible":true,"origin":"","legend":"\u003cp\u003eFigure 3a. Axial CTA image revealing markedly enlarged vascular structure within the transplant kidney measuring 70.5 x 24.2 mm (arrow).\u003c/p\u003e","description":"","filename":"Picture3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9500905/v1/722469878c2a03d17d64b39f.jpg"},{"id":109150404,"identity":"1e04b73e-173e-4309-92ad-537694cd6805","added_by":"auto","created_at":"2026-05-13 05:28:20","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":110373,"visible":true,"origin":"","legend":"\u003cp\u003eFigure 3b. Coronal CTA image confirming early venous opacification of the right common iliac vein during the arterial phase (arrow), highly suggestive of a transplant-kidney AVF.\u003c/p\u003e","description":"","filename":"Picture4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9500905/v1/056de745839fbc151baaf4c3.jpg"},{"id":109150403,"identity":"3af7c924-27ec-4565-8f7c-6eeefa1fe869","added_by":"auto","created_at":"2026-05-13 05:28:20","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":232923,"visible":true,"origin":"","legend":"\u003cp\u003eFigure 4a–c. Diagnostic angiograms of the transplant renal artery demonstrating a large AVF in the superior pole supplied by anterior and posterior branches.\u003c/p\u003e","description":"","filename":"Picture5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9500905/v1/4d460c27b9eebdbe9af24ef1.jpg"},{"id":109150405,"identity":"207c5087-e95b-4cbf-a168-70fde92ec879","added_by":"auto","created_at":"2026-05-13 05:28:20","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":66878,"visible":true,"origin":"","legend":"\u003cp\u003eFigure 5a. Embolization of the anterior renal-artery feeder using a POD3 20 cm coil (red arrow) and a 4 mm × 10 cm Ruby coil (blue arrow).\u003c/p\u003e","description":"","filename":"Picture6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9500905/v1/87079e56f0650caa617f0e8a.jpg"},{"id":109150406,"identity":"43c379e1-361c-4892-b54c-39abf8f65c89","added_by":"auto","created_at":"2026-05-13 05:28:20","extension":"jpg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":42303,"visible":true,"origin":"","legend":"\u003cp\u003eFigure 5b. Embolization of the posterior renal-artery feeders with Azur 6 mm × 17 cm, 5 mm × 11 cm, and 4 mm × 7 cm coils.\u003c/p\u003e","description":"","filename":"Picture7.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9500905/v1/a0589b20e10c05b86ae7fbfc.jpg"},{"id":109150399,"identity":"46f0c0fc-f92a-4189-84c8-9c31ddafab1c","added_by":"auto","created_at":"2026-05-13 05:28:20","extension":"jpg","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":176793,"visible":true,"origin":"","legend":"\u003cp\u003eFigure 6a–b. Final angiograms demonstrating complete occlusion of the AVF with preserved flow through the main transplant renal artery.\u003c/p\u003e","description":"","filename":"Picture8.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9500905/v1/14f5299029205d9b7171dedb.jpg"},{"id":109150412,"identity":"1284622f-520e-4cb2-aa12-709ed5e21e56","added_by":"auto","created_at":"2026-05-13 05:28:23","extension":"jpg","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":69201,"visible":true,"origin":"","legend":"\u003cp\u003eFigure 7. Post-embolization doppler ultrasound showing absence of flow within the previously identified AVF, confirming success.\u003c/p\u003e","description":"","filename":"Picture9.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9500905/v1/be9da87a22115deaeb52a65b.jpg"},{"id":109150401,"identity":"b57ab0df-6ac2-498d-a8f1-f98d1b1bf404","added_by":"auto","created_at":"2026-05-13 05:28:20","extension":"jpg","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":221763,"visible":true,"origin":"","legend":"\u003cp\u003eFigure 8a-b. (a) Axial and (b) coronal images from follow-up CTA four days post-embolization showing no residual aneurysm, fistula, or contrast extravasation, confirming complete resolution of the transplant-kidney AVF.\u003c/p\u003e","description":"","filename":"Picture10.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9500905/v1/20385587277911ebaedd67f1.jpg"},{"id":109205122,"identity":"bd17d2f3-d227-4bf4-ad2f-ede09a2b59ed","added_by":"auto","created_at":"2026-05-13 15:03:26","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1265590,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9500905/v1/662ea765-efb0-4089-8e5f-925f213902cd.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Embolization of a Large Arteriovenous Fistula in a Transplanted Kidney: A Case Report","fulltext":[{"header":"Background","content":"\u003cp\u003eArteriovenous fistulas (AVFs) are rare but serious complications in transplant kidneys, with an estimated incidence of 6\u0026ndash;8% in kidney transplant recipients. AVFs in a transplant setting usually result from trauma, biopsy procedures, or inadvertent surgical complications. Although most are small and resolve spontaneously, larger AVFs can lead to hematuria, kidney dysfunction, and eventually high-output heart failure due to volume overload. Transcatheter embolization is the preferred management technique for larger or symptomatic AVFs due to its efficacy and kidney-sparing nature. We report a case of a large transplant-kidney AVF successfully treated with coil embolization, emphasizing the imaging evolution, interventional approach, and clinical outcome.\u003c/p\u003e"},{"header":"Case Presentation","content":"\u003cp\u003eA 56-year-old male with a history of end-stage renal disease (ESRD) on hemodialysis, kidney transplant in 2015, hypertension, diabetes, and heart failure, presented with complaints of altered mental status, hematuria, and confusion. The patient was empirically started on Vancomycin and Zosyn, transfused one unit of blood for anemia, and admitted to the intermediate care unit for sepsis workup.\u003c/p\u003e \u003cp\u003eOn the third day of hospitalization, a contrasted CT of the abdomen and pelvis was performed to evaluate for possible malignancy due to persistent hematuria. The CT revealed diffuse enlargement of the right transplant kidney with loss of normal corticomedullary differentiation, concerning for lymphoproliferative disease. Additionally, a pseudoaneurysm was noted in the superior medial aspect of the transplant kidney, measuring 1.4 x 2.2 x 1.6 cm (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). An ultrasound of the transplant kidney was also ordered which showed increased echogenicity with a \u0026ldquo;yin-yang\u0026rdquo; sign, consistent with turbulent flow (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). At that time, embolization was suggested to the transplant service but was not agreed upon as they expected to explant the kidney due to lymphoproliferative disorder.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eOver the next two weeks, the patient's hematuria persisted, prompting further evaluation. A repeat CTA of the abdomen and pelvis revealed a significantly enlarged tubular vascular structure within the transplant kidney measuring 70.5 \u0026times; 24.2 mm (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e3\u003c/span\u003ea), with early venous opacification of the right common iliac vein during the arterial phase (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e3\u003c/span\u003eb), findings strongly suggestive of a large AVF. No active bleeding or peritransplant hematoma was identified.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eGiven the size of the AVF and ongoing symptoms, interventional radiology was consulted for endovascular treatment.\u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eEndovascular Procedure:\u003c/h2\u003e \u003cp\u003e Using ultrasound-guided retrograde right common femoral artery access, a 5 Fr \u0026times; 10 cm sheath was placed. A diagnostic angiogram performed via a 5 Fr Glide catheter confirmed a large AVF in the superior portion of the transplant kidney, supplied by both anterior and posterior branches of the transplant renal artery (Figs.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e4\u003c/span\u003ea,b,c).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eSelective microcatheterization was performed with a Lantern microcatheter to target each feeding vessel:\u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003eAnterior renal artery: occluded with one POD3 20 cm coil and one 4 mm \u0026times; 10 cm Ruby coil (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e5\u003c/span\u003ea).\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003ePosterior renal artery: occluded with Azur 6 mm \u0026times; 17 cm, 5 mm \u0026times; 11 cm, and 4 mm \u0026times; 7 cm coils (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e5\u003c/span\u003eb).\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e5\u003c/span\u003ea. \u003cem\u003eEmbolization of the anterior renal-artery feeder using a POD3 20 cm coil (red arrow) and a 4 mm \u0026times; 10 cm Ruby coil (blue arrow).\u003c/em\u003e\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e Sequential angiograms demonstrated progressive reduction and then complete cessation of flow through the fistula. Final angiography showed total occlusion of the AVF with preservation of the main renal artery flow (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e6\u003c/span\u003ea,b).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe puncture site was closed using an Angio-Seal device. Estimated blood loss was \u0026lt;\u0026thinsp;10 mL. The patient remained hemodynamically stable throughout.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003ePost-Procedure Course:\u003c/h3\u003e\n\u003cp\u003e \u003c/p\u003e \u003cp\u003eThe patient\u0026rsquo;s hematuria subsided within 24 hours. A post-procedure Doppler ultrasound confirmed absence of flow within the embolized AVF (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e7\u003c/span\u003e). He was maintained on bed rest for four hours.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e A follow-up CTA abdomen and pelvis four days later (Figs.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e8\u003c/span\u003ea and \u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e8\u003c/span\u003eb) demonstrated no residual aneurysm, fistula, or active contrast extravasation, confirming durable occlusion. The patient was in stable condition, with complete resolution of hematuria and preserved graft perfusion.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eArteriovenous fistulas (AVFs) are abnormal connections between arteries and veins, bypassing the normal capillary network. In transplant kidneys, these AVFs can occur due to surgical trauma, biopsy procedures, or other post-operative complications.\u003c/p\u003e \u003cp\u003eA large AVF permits arterial blood to bypass the high-resistance capillary network, causing a fall in systemic vascular resistance. To maintain perfusion, stroke volume, heart rate, and cardiac output increase. Sustained shunting increases venous return, resulting in ventricular dilation, left-ventricular hypertrophy, and eventual high-output failure. Locally, continuous shunting may lead to renal ischemia, pseudoaneurysm formation, and graft dysfunction.\u003c/p\u003e \u003cp\u003eColor Doppler ultrasound is the initial modality of choice, demonstrating turbulent bidirectional flow (\u0026ldquo;yin-yang\u0026rdquo; sign) and spectral broadening. CT angiography provides detailed vascular anatomy, defining the feeding artery, draining vein, and associated pseudoaneurysm.\u003c/p\u003e \u003cp\u003eInterventional radiology offers a minimally invasive method for treating AVFs in renal transplant recipients. Embolization using coils is considered the gold standard, as it directly occludes the feeding arteries, preventing further blood flow through the fistula. Coils, such as POD3, Ruby, and Azur, were used in this case to effectively occlude the feeding vessels. Embolization is typically preferred over surgical interventions due to its minimally invasive nature, reduced complication rates, and shorter recovery times. The use of microcatheters for selective cannulation allows for precise embolization and effective management of the AVF.\u003c/p\u003e \u003cp\u003eThe success of embolization is confirmed by post-procedural imaging, including angiography and ultrasound. In this case, both the angiogram and ultrasound demonstrated no residual blood flow, indicating complete occlusion of the AVF. Long-term outcomes are excellent, with most patients demonstrating complete resolution of hematuria and stable graft function. Our patient remained asymptomatic with no evidence of residual AVF or pseudoaneurysm on follow-up CTA.\u003c/p\u003e \u003cp\u003eThis case reinforces the crucial role of interventional radiology in diagnosing and managing vascular complications of renal transplantation. Early recognition and minimally invasive therapy prevent progression to heart failure or graft loss while minimizing patient morbidity.\u003c/p\u003e"},{"header":"Declarations","content":" \u003cp\u003e \u003cstrong\u003eEthics approval and consent to participate:\u003c/strong\u003e \u003cp\u003eThis study involves a single patient case report. Ethical approval was not required in accordance with institutional guidelines.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eConsent for publication:\u003c/strong\u003e \u003cp\u003e Written informed consent was obtained from the patient for publication of this case report and any accompanying images.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding:\u003c/h2\u003e \u003cp\u003eThe authors received no specific funding for this work.\u003c/p\u003e \u003cp\u003eAcknowledgements:\u003c/p\u003e \u003cp\u003eNot applicable.\u003c/p\u003e \u003cp\u003eAuthors\u0026rsquo; information:\u003c/p\u003e \u003cp\u003eNot applicable.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eI.E., M.G., A.E. managed the patient. H.Q. and A.E. performed the literature review and drafted the manuscript. All authors read and approved the final version.\u003c/p\u003e\u003ch2\u003eAvailability of data and materials:\u003c/h2\u003e \u003cp\u003eAll data generated or analyzed during this study are included in this published article. Additional information is available from the corresponding author on reasonable request.\u003c/p\u003e \u003cp\u003eCompeting interests:\u003c/p\u003e \u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eVij G, Hamper UM, De Jong MR, Scoutt LM. A pot pourri of abdominal Doppler cases. \u003cem\u003eUltrasound Clin\u003c/em\u003e. 2011; 6(4):531\u0026ndash;550. doi:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.cult.2011.07.005\u003c/span\u003e\u003cspan address=\"10.1016/j.cult.2011.07.005\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCrotty KL, Orihuela E, Warren MM. Recent advances in the diagnosis and treatment of renal arteriovenous malformations and fistulas. \u003cem\u003eJ Urol\u003c/em\u003e. 1993; 150(5 Pt 1):1355\u0026ndash;1359. doi:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/S0022-5347(17)35778-6\u003c/span\u003e\u003cspan address=\"10.1016/S0022-5347(17)35778-6\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNagpal P, Bathla G, Saboo SS, et al. Giant idiopathic renal arteriovenous fistula managed by coils and Amplatzer device: Case report and literature review. \u003cem\u003eWorld J Clin Cases\u003c/em\u003e. 2016; 4(11):364\u0026ndash;368. doi:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.12998/wjcc.v4.i11.364\u003c/span\u003e\u003cspan address=\"10.12998/wjcc.v4.i11.364\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTynes WV, Devine CJ, Devine PC, Poutasse EF. Surgical treatment of renal arteriovenous fistulas: Report of 5 cases. \u003cem\u003eJ Urol\u003c/em\u003e [Internet]. 1970 Jun 1 [cited 2025 Nov 4]; 103(6):692\u0026ndash;698. Available from: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/S0022-5347(17)62029-9\u003c/span\u003e\u003cspan address=\"10.1016/S0022-5347(17)62029-9\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFogazzi GB, Moriggi M, Fontanella U. Spontaneous renal arteriovenous fistula as a cause of haematuria. \u003cem\u003eNephrol Dial Transplant\u003c/em\u003e. 1997; 12(2):350\u0026ndash;356. doi:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1093/ndt/12.2.350\u003c/span\u003e\u003cspan address=\"10.1093/ndt/12.2.350\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDuc VT, Duong NQT, Phong NT, Nam NH, Quoc DA, Cuong TTQ, Huy NH, Duy TL, Chien PC. Large renal arteriovenous fistula treated by embolization: A case report. \u003cem\u003eRadiol Case Rep\u003c/em\u003e. 2021; 16(8):2289\u0026ndash;2294. doi:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.radcr.2021.05.058\u003c/span\u003e\u003cspan address=\"10.1016/j.radcr.2021.05.058\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\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":"Arteriovenous fistula, Kidney transplant, Embolization, Interventional radiology, Pseudoaneurysm, Renal vascular complication","lastPublishedDoi":"10.21203/rs.3.rs-9500905/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9500905/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground:\u003c/h2\u003e \u003cp\u003eArteriovenous fistulas of transplanted kidneys are uncommon but potentially serious vascular complications, most often occurring after biopsy or surgical trauma. While many are small and resolve spontaneously, large fistulas can cause persistent hematuria, graft dysfunction, and hemodynamic compromise. Early recognition is critical, as delayed diagnosis may lead to significant morbidity or unnecessary graft loss. This case highlights the evolution of a large transplant-kidney arteriovenous fistula and demonstrates successful minimally invasive management using endovascular coil embolization.\u003c/p\u003e\u003ch2\u003eCase presentation:\u003c/h2\u003e \u003cp\u003eA 56-year-old male with a history of end-stage renal disease on hemodialysis and prior kidney transplantation presented with persistent hematuria and altered mental status. Initial computed tomography of the abdomen and pelvis revealed diffuse enlargement of the transplanted kidney with loss of normal corticomedullary differentiation, concerning for lymphoproliferative disease, along with a pseudoaneurysm. Conservative management was initially pursued. Due to ongoing hematuria, repeat computed tomography angiography demonstrated a markedly enlarged vascular structure within the transplant kidney with early venous opacification, consistent with a large arteriovenous fistula. Interventional radiology performed endovascular embolization via femoral artery access. Selective catheterization identified anterior and posterior renal arterial feeders, which were successfully occluded using a combination of detachable coils. Completion angiography confirmed complete occlusion of the fistula with preservation of the main renal arterial flow. Post-procedural ultrasound and follow-up computed tomography angiography showed no residual flow.\u003c/p\u003e\u003ch2\u003eConclusions:\u003c/h2\u003e \u003cp\u003eThis case demonstrates that large arteriovenous fistulas in transplanted kidneys can develop and progress during hospitalization and should be considered in patients with persistent hematuria. Endovascular coil embolization is a safe and effective treatment that allows for targeted occlusion of the fistula while preserving renal perfusion. Early diagnosis and minimally invasive intervention can prevent complications and may avoid the need for surgical graft removal.\u003c/p\u003e","manuscriptTitle":"Embolization of a Large Arteriovenous Fistula in a Transplanted Kidney: A Case Report","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-05-13 05:27:46","doi":"10.21203/rs.3.rs-9500905/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":"a8b41649-b6b6-4756-b0a5-b42863669bdf","owner":[],"postedDate":"May 13th, 2026","published":true,"recentEditorialEvents":[{"type":"editorInvitedReview","content":"","date":"2026-05-09T12:04:04+00:00","index":11,"fulltext":""},{"type":"reviewerAgreed","content":"245469361615095924041128547416514466645","date":"2026-05-06T11:00:14+00:00","index":10,"fulltext":""},{"type":"reviewersInvited","content":"4","date":"2026-05-04T09:15:38+00:00","index":"","fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-05-13T05:27:47+00:00","versionOfRecord":[],"versionCreatedAt":"2026-05-13 05:27:46","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9500905","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9500905","identity":"rs-9500905","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}