Abdominal pain is a common reason for visits to pediatric emergency departments (EDs), accounting for approximately 32% of all non-injury-related pain visits in the United States (1). While many of these cases are benign, renal artery thrombosis is a rare but time-sensitive diagnosis, requiring a high index of suspicion for timely diagnosis and optimal outcomes. There are only a handful of cases described in the literature, none involving pediatric patients (2-4). The presenting symptoms are often nonspecific, such as acute pain in the abdomen, flank, or lower back, which may be accompanied by fever, nausea, or vomiting. Laboratory findings often show leukocytosis, albuminemia, microscopic hematuria, or proteinuria (2). Renal artery thrombosis typically affects adults aged 30-50 years, where thromboembolism usually originates from the heart or aorta (2). Although thrombi or emboli arising directly from the renal artery are rare, they may occur in association with risk factors such as blunt trauma, atrial fibrillation, atherosclerosis, prior renal surgery, renal arterial stents, systemic lupus erythematosus, hypercoagulable states, pregnancy, or oral contraceptive use (2,5-8).

Spontaneous renal arterial thrombosis is rarer than the abovementioned secondary renal artery thrombosis, particularly in the pediatric population (2). Due to the nonspecific nature of its clinical presentation and time-sensitive implications, it is crucial for pediatricians or emergency physicians to consider this diagnosis in the differential when evaluating any pediatric patients with acute abdominal pain, even in the absence of the risk factors. To our knowledge, there have been no published reports of spontaneous renal artery thrombosis in pediatric patients. Informed consent was obtained from the patient’s legal guardians for publication of this case report.

A 14-year-old female with a history of long QT syndrome (now resolved) presented to the pediatric ED with sudden onset right lower quadrant (RLQ) abdominal pain and nausea. The pain developed in the morning and localized to the RLQ associated with pain on the ipsilateral lower back, which worsened en route to the ED due to uneven roads. She denied fever, vomiting, diarrhea, dysuria, hematuria, or changes in urinary frequency. Her last menstrual period was 2 weeks ago, and she had no history of trauma, surgery, hormonal contraceptive use, or recent sexual activity. There was no family history of clotting disorders, hyperlipidemia, heart diseases, or renal diseases.

The initial vital signs were as follows: blood pressure, 134/100 (≥ 99th percentile for the age/sex); heart rate, 75 beats/minute; respiratory rate, 14 breaths/minute; and temperature, 36.6 °C. Her weight and height were 47.2 kg (40th percentile) and 160.5 cm (50th percentile). She appeared slightly uncomfortable due to the pain but was not in acute distress. Her abdomen was soft but tender to palpation over the RLQ with no guarding or rebound, and mild right costovertebral angle tenderness. Initial laboratory findings showed a white blood cell count, 11,810/μL; blood urea nitrogen, 12.0 mg/dL; and creatinine, 1.0 mg/dL, as well as urinalysis findings: white blood cell count, 1 cell/high-power field; red blood cell, < 1 cell/high-power field; specific gravity, 1.038 (reference value, 1.005-1.030); ketone, 15 mg/dL (reference value, negative); and beta-human chorionic gonadotropin, negative.

The patient initially received intravenous 0.9% saline, ketorolac tromethamine and morphine sulfate for the pain, ondansetron and metoclopramide for the nausea, and ceftriaxone. A comprehensive pelvic and abdominal ultrasonography failed to visualize the appendix but limitedly visualized the ovaries with no overt signs of torsion. Given her persistent symptoms, a contrast-enhanced computed tomography (CT) scan of the abdomen and pelvis was conducted and showed a right renal artery occlusion with no enhancement of the ipsilateral kidney, indicating the presence of thrombosis (Fig. 1).

Upon receiving the radiographic finding, a multidisciplinary approach was performed, involving the Departments of Urology, General Surgery, Vascular Surgery, Hematology, and Interventional Radiology, in order to determine the best therapeutic plan against the renal artery occlusion. She was taken urgently to an operating room on day 1 for renal angiography with a possible catheter-directed thrombectomy, thrombolysis, or angioplasty. On the angiogram, she was found to have a completely occlusive thrombus of the right renal artery (Fig. 2A). A transition point within the main right renal artery prevented free passage of a wire catheter, suggesting a possible web. After infusion of 2 mg of alteplase and subsequent thrombectomy using the Angiojet (Boston Scientific), no improvement was observed. Subsequently, an angioplasty of the artery using a 4-mm balloon (Boston Scientific) was performed to macerate the thrombus, and to disrupt the suspected web. While recovering the anatomical patency of the artery, a peripheral showering of the thrombi was found, which required an overnight catheter-directed alteplase infusion into the right renal artery (Fig. 2B). The alteplase infusion was started at a dose of 0.5 mg/hour for 6 hours before decreasing to 0.25 mg/hour. She was also started on a low-dose heparin infusion at 100 U/hour via a right femoral catheter. She was hospitalized in the pediatric intensive care unit.

A follow-up angiography on day 2 showed patency of the right renal artery with no definite residual thrombosis. Therefore, thrombolytic and anticoagulant therapies were stopped after 8 hours and 15 hours, respectively. She was discharged on rivaroxaban on day 5. Etiologic evaluation showed no hypercoagulable risk factors. Since the discharge, a magnetic resonance angiography at a 6-month follow-up showed an atrophic right kidney with compensatory hypertrophy of the left. Her creatinine concentrations peaked at 1.1 mg/dL on day 3 during her hospitalization but thereafter declined through 2-, 4-, and 7-month follow-ups. Her estimated glomerular filtration rate was calculated at 63 mL/minute/1.73 m² at 7-month follow-up. Given the elevated creatinine with size discrepancy of the kidneys, a dimercaptosuccinic acid scan was planned to assess renal scarring at the time of writing.

Our patient presented with RLQ pain and nausea. Initial laboratory findings showed a mild leukocytosis without hematuria. Given the location of her pain and sex, a formal ultrasonography was initially performed to evaluate for possible appendicitis or ovarian pathologies, showing inconclusive findings. The diagnosis was indicated by the contrast-enhanced CT scan, which was subsequently obtained to further evaluate for intra-abdominal pathologies.

This case is unique in that the patient had no abovementioned typical risk factors for renal artery thrombosis. This underscores the importance of maintaining a broad differential diagnosis for acute abdominal pain and prompt implementation of imaging studies. Ultrasonography is a typical initial imaging modality used in the workup of acute abdominal pain in pediatric patients. In addition, the use of Doppler techniques can provide crucial information on organ perfusion, particularly in cases of vascular impairment (9). In our case, however, the differential at that time was limited to ovarian or pelvic pathologies, or appendicitis. Therefore, the use of Doppler techniques was omitted, and the ultrasonography was limited in providing any significant information. Thus, contrast-enhanced CT was essential for confirming the diagnosis. Although catheter angiography remains the gold standard for diagnosing renal infarction, contrast-enhanced CT is often preferred in EDs due to its noninvasiveness, convenience, and ability to identify extra-renal ischemia or other causes of abdominal pain.

There are currently no established therapeutic guidelines for renal artery thrombosis, given its rarity. Literature suggests that early anticoagulation is associated with restored perfusion and favorable outcomes (9-12). Thrombolysis within 6 hours of diagnosis has shown improved outcomes, and surgical interventions such as thrombectomy and stenting have also been described (2,13,14).

Our patient initially underwent thrombolysis and thrombectomy for the complete renal artery occlusion but with no improvement. The angioplasty was then performed, resulting in a good anatomical outcome, albeit complicated by the showering thrombi. The overnight catheter-directed thrombolytic infusion was performed, and the wide patency of the renal artery was shown on the follow-up angiogram (Fig. 2B). Despite improvement in the creatinine, her right kidney remained atrophic with compensatory hypertrophy of the contralateral kidney. This suboptimal outcome was likely affected by the size of the thrombus, occlusion percentage, or delayed revascularization (> 6 hours since initial presentation).

This case highlights the importance of maintaining a broad differential when evaluating acute abdominal pain. Although spontaneous renal artery thrombosis is rare in pediatric patients, it carries clinical implications and should be considered in the differential diagnosis. For timely diagnosis, it is crucial for pediatricians or emergency physicians to have a high index of suspicion and promptly perform imaging studies.