Contrast-enhanced ultrasonography as a first-line triage tool for vascular complications after percutaneous nephrolithotomy: A preliminary diagnostic and therapeutic algorithm

Introduction Percutaneous nephrolithotomy (PCNL) remains the standard treatment for large stone burdens or complex stones greater than 2 cm.1 However, massive hemorrhage after PCNL is a common and severe complication that may lead to a prolonged hospital stay, impaired renal function, and even life-threatening conditions, necessitating timely and effective intervention and treatment. Monitoring and early diagnosis of postoperative bleeding are crucial for timely intervention. In recent years, contrast-enhanced ultrasound (CEUS) has emerged as a novel, noninvasive imaging technique. By using microbubble contrast agents to enhance ultrasound signals, CEUS provides clearer and more dynamic vascular imaging.2 It is capable of real-time monitoring of renal hemodynamic changes, allowing for the prompt detection of bleeding sources, such as renal pseudoaneurysms and arteriovenous fistulas. Compared with traditional imaging techniques, CEUS has several advantages, such as the absence of radiation exposure, no requirement for iodinated contrast agents, and high repeatability. It is especially suitable for patients with renal insufficiency or those with allergies to conventional contrast agents.3 We conducted a retrospective review of 15 consecutive cases in which patients underwent CEUS evaluation for clinically significant hemorrhage after PCNL procedures at our institution from May 2018 to May 2025 to investigate the diagnostic and therapeutic utility of CEUS in managing major post-PCNL bleeding complications. 2. Materials and methods This study included 15 men (age range, 34–75 years; mean age, 51.9 years) with normal coagulation function who underwent CEUS for suspected massive bleeding after PCNL. The clinical details and stone characteristics are summarized in Table 1. Table 1 - Clinical characteristics, diagnostic findings, and management of patients with postoperative bleeding. Patient ID Sex Age, yr BMI, kg/m2 Puncture site Time to bleeding onset, d Hemoglobin drop, g/L Transfusionblood CUES frequency CUES findings DSA findings Management 1 Male 52 23.5 Left, middle 7 55 Yes Once Arteriovenous fistula Arteriovenous fistula Embolization 2 Male 64 19.5 Right mid/lower 10 62 Yes Once Pseudoaneurysm Pseudoaneurysm Embolization 3 Male 45 24.1 Left middle 6 42 Yes Twice in 2 days Pseudoaneurysm Pseudoaneurysm Embolization 4 Male 51 22.7 Left lower 60 23 No Once Pseudoaneurysm Pseudoaneurysm Embolization 5 Male 75 24.8 Left middle 5 46 No Once Pseudoaneurysm Pseudoaneurysm Embolization 6 Male 65 25.3 Right middle 1 58 Yes Twice in 2 days No active bleeding No bleeding focus Conservative 7 Male 44 24.8 Right middle 5 37 No Twice in 4 days No active bleeding Not performed Conservative 8 Male 42 20.8 Right middle 5 28 No Once No active bleeding Not performed Conservative 9 Male 58 30.1 Left middle 3 31 Yes Once No active bleeding Not performed Conservative 10 Male 34 21.9 Left middle 7 20 No Twice in 3 days No active bleeding Not performed Conservative 11 Male 57 27.7 Right middle 1 24 No Once No active bleeding Not performed Conservative 12 Male 42 31.8 Right middle 3 47 No Once No active bleeding Not performed Conservative 13 Male 52 34.6 Left mid/lower 1 10 No Once No active bleeding Not performed Conservative 14 Male 58 24.8 Left middle 2 23 Yes Twice in 4 days Pseudoaneurysm Pseudoaneurysm Embolization 15 Male 40 24.5 Left mid/lower 3 15 No Once No active bleeding Not performed Conservative All patients in this cohort were male. Management strategies included embolization (for confirmed vascular abnormalities) or conservative treatment (when no active bleeding was identified). CEUS = contrast-enhanced ultrasonography; BMI = body mass index; DSA = digital subtraction angiography. Contrast-enhanced ultrasound examinations were performed using a Hitachi ARIETTA 70 ultrasound system equipped with a C251 convex-array transducer (frequency range, 1–5 MHz). The contrast imaging protocol employed a low mechanical index (20 g/L within 24 hours); Hemodynamic instability (systolic blood pressure 120 bpm); Delayed cyclical bleeding episodes. 2.2. Standardized contrast-enhanced ultrasound protocol Systematic evaluation of renal morphological changes, with emphasis on measuring pelvicalyceal dilation and subcapsular hematoma volume; Optimization of scanning planes, followed by switching to contrast mode with probe stabilization; Rapid bolus injection of the contrast agent via the antecubital vein, synchronized with initiation of dynamic recording; Continuous monitoring of renal parenchymal enhancement patterns, contrast extravasation into the collecting system, and abnormal vascular structures; Differentiation between pseudoaneurysms (early enhancement with delayed washout) and arteriovenous fistulas (high-velocity turbulence with early venous opacification). Vital signs were continuously monitored during the examination. Upon identification of active bleeding foci, an immediate referral to the interventional radiology department for renal artery angiography and super-selective embolization was performed. Patients with negative CEUS findings were transferred to an intensified clinical observation protocol, with repeat CEUS evaluation if necessary (minimum interval, ≥6 hours). 3. Results Among the 15 patients suspected of having major post-PCNL hemorrhage, CEUS identified renal pseudoaneurysms in 5 cases (Fig. 1) and an arteriovenous fistula in 1 case (Table 1). All 5 pseudoaneurysms and the single arteriovenous fistula with positive CEUS findings underwent confirmatory renal artery angiography, followed by super-selective renal artery embolization (SRAE), achieving complete resolution. Of the remaining 9 cases with no active bleeding on CEUS, 1 patient underwent additional renal artery angiography, which confirmed the absence of bleeding foci. All 9 patients without active bleeding on CEUS recovered with conservative management alone. A 100% concordance rate was observed between CEUS and angiography results in the 7 patients who underwent both examinations (Table 1). Contrast-enhanced ultrasound demonstrated high diagnostic accuracy in differentiating vascular complications (pseudoaneurysms vs. arteriovenous fistulas) and guiding appropriate interventions.Figure 1.: Contrast-enhanced ultrasonography revealed a hyper-enhanced nodule adjacent to the left nephrostomy tube postoperatively, suggestive of pseudoaneurysm formation.4. Discussion In this study, diagnostic concordance (100%) was observed between CEUS and angiography in all 7 patients who underwent both CEUS and digital subtraction angiography (DSA), which supports CEUS as a first-line imaging modality for evaluating post-PCNL hemorrhage, enabling timely diagnosis of vascular injuries while optimizing resource utilization. Management of suspected severe post-PCNL hemorrhage presents a significant clinical dilemma, particularly regarding the timing of diagnostic angiography and subsequent embolization. Premature interventions may yield negative angiographic findings, creating undue psychological stress for both clinicians and patients, whereas delayed interventions risk missing the critical therapeutic window. This clinical challenge underscores the importance of 2 key determinants of successful outcomes: (1) accurate early recognition of arterial bleeding patterns, and (2) precise execution of SRAE when indicated. Traditionally, imaging techniques, such as computed tomography angiography and DSA, have been employed for the surveillance of bleeding following PCNL. Digital subtraction angiography remains the gold standard for the diagnosis and treatment of renal artery lesions, allowing for more precise localization of bleeding sites and direct hemostatic intervention. When renal vascular bleeding occurs after PCNL and DSA reveals findings, such as pseudoaneurysms, arteriovenous fistulas, arterial lacerations, or active contrast extravasation, these findings are indicative of active renal bleeding and necessitate timely SRAE.4 The primary types of vascular lesions observed on DSA after PCNL include arterial lacerations, pseudoaneurysms, and arteriovenous fistulas. While computed tomography angiography and DSA are highly valuable for diagnosing renal pseudoaneurysms and other vascular abnormalities, these methods also have certain limitations, such as radiation exposure, contrast agent-related allergic reactions, nephrotoxicity, high technical demands on operators, and relatively high costs. Moreover, these procedures are invasive. Therefore, the availability of simpler, safer, less expensive, and more accessible assessment methods remains an important clinical consideration. Contrast-enhanced ultrasound is a technique that utilizes contrast agents to enhance backscatter echoes, thereby significantly improving the resolution, sensitivity, and specificity of ultrasound diagnosis. Currently, there are only a few reports on the use of CEUS to evaluate bleeding after PCNL.5 Theoretically, CEUS can monitor and visualize intrarenal bleeding, including the formation of pseudoaneurysms and arteriovenous fistulas, thereby providing timely diagnostic evidence for clinicians and allowing for a more accurate and timely assessment of a patient’s bleeding status. Contrast-enhanced ultrasound is also a relatively safe, effective, and noninvasive imaging method, with advantages, such as real-time and dynamic imaging, good repeatability, no radiation exposure, and no requirement for iodinated contrast agents. It has minimal impact on renal function and is particularly suitable for the postoperative monitoring of patients with renal insufficiency. In addition, CEUS is easy to perform and can be repeated within a short period to provide real-time information for clinical decision-making. In this study, 5 patients underwent multiple examinations within a few days, which facilitated timely monitoring of disease progression. In cases of active arterial bleeding, CEUS can also provide preliminary localization for SRAE, thereby reducing procedural time, unnecessary procedural risks, and complications. In this study, the interpretations of CEUS and DSA were consistent in 7 patients. All patients for whom conservative management was indicated based on CEUS findings were successfully managed conservatively. Qin et al.5 reported that CEUS could be used to monitor bleeding after PCNL at any time and repeatedly to clarify the presence of renal pseudoaneurysms and/or arteriovenous fistulas, providing diagnostic and therapeutic evidence for timely SRAE. We recommend CEUS as the first choice for postoperative follow-up examinations. Unlike a previous study that utilized CEUS solely as a passive surveillance modality, our protocol elevates its role as the cornerstone of clinical decision-making for post-PCNL hemorrhage. Conservative management is indicated when CEUS demonstrates (1) absence of microbubble extravasation, and (2) hemodynamic stability. Dynamic CEUS monitoring is reserved for cases with equivocal initial findings, suspected delayed hemorrhage, or high-risk anatomical features (including signs of fornix rupture). Escalation to DSA and embolization is warranted when (1) progressive contrast extravasation, (2) pseudoaneurysm and/or arteriovenous fistula formation, or (3) clinical deterioration despite conservative measures is detected. This risk-stratified algorithm enhances management precision while reducing unnecessary invasive interventions. However, our study was retrospective and had a small sample size. Further prospective studies with larger cohorts are required to validate the reliability of these results. It is important to note that CEUS requires significant skill and experience. Different operators may interpret the same lesion differently, which may affect diagnostic consistency and accuracy. 5. Conclusions Our study established CEUS as a highly effective first-line triage tool for diagnosing and managing vascular complications after PCNL. The proposed algorithm, which is centered on the initial application of bedside CEUS, provides a clear and efficient clinical pathway. By facilitating precise diagnosis, CEUS guides timely and appropriate interventions, thereby improving patient outcomes, reducing the need for more invasive procedures, and optimizing resource utilization. Statement of ethics Due to the retrospective nature of the study and the use of anonymized patient data, the requirement for informed consent was waived by the Ethics Committee of The Seventh Affiliated Hospital, Sun Yat-sen University (approval number: KY-2025-326-01). All patient data were handled anonymously to protect privacy. All procedures performed in this study involving human participants were in accordance with the ethical standards of the institutional and national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. Acknowledgements None. Conflict of interest statement SZ is a member of the Early Career Editorial Board of CurrentUrology and confirms that there was no involvement in any stage of this article’s review process, ensuring unbiased editorial decision-making. The remaining authors have no conflicts of interest to disclose Funding source None. Author contributions SZ: Protocol development, data collection, data management, and manuscript writing. SZ and HX: Manuscript editing. LJ: Data collection. YS: Data collection, data management, and data analysis. JL: Data collection. HX: Protocol and project development and data analysis. SZ and HX contributed equally to this study. Data availability The datasets generated and/or analyzed during the current study are not publicly available but are available from the corresponding author upon reasonable request.