Unmasking the Enigma: A Case Series on Idiopathic Renal Arteriovenous Malformations

Renal arteriovenous malformations (rAVMs) are rare vascular abnormalities with a global prevalence of only 0.04%. Characterized by dilated, tortuous vessels formed by abnormal communications between renal arteries and veins, these malformations lack an intervening capillary network, leading to the shunting of high-pressure arterial blood into low-pressure veins. Although typically affecting individuals aged 30 - 40, our case series from East Malaysia reveals a notable prevalence among older patients, predominantly females. rAVMs can be classified into congenital, idiopathic, and acquired types, with acquired forms accounting for 70% - 80% of cases. Diagnosing rAVMs can be challenging due to their varied clinical presentations; patients may be asymptomatic or present with hematuria, flank pain, or even life-threatening hemorrhage. Imaging techniques such as Doppler ultrasound, Computer topography, and magnetic resonance imaging are essential for visualization and assessment. Management strategies range from conservative observation in asymptomatic cases to endovascular embolization or surgical resection for symptomatic patients. This case series highlights the clinical presentations, demographic factors influencing rAVM prevalence, and management approaches, aiming to enhance understanding and improve treatment protocols for these complex vascular anomalies. Renal arteriovenous malformations (rAVMs) are infrequent vascular anomalies predominantly occurring in the left kidney, often involving the upper pole and typically affecting the collecting system rather than renal parenchyma. In this case series, all patients were female, supporting the known gender predisposition, as rAVMs affect females twice as often as males. Contrary to the expected peak incidence in individuals aged 30 - 40, most patients presented with symptoms in their sixth and seventh decades of life. rAVMs can be classified into congenital and acquired types, with acquired forms accounting for 70% - 80% of cases, frequently linked to iatrogenic injuries. Congenital rAVMs result from developmental failures and remain asymptomatic until adulthood. This series highlights a notable prevalence of rAVMs in East Malaysia, particularly in Sabah. The underlying mechanisms of rAVM formation are not fully understood, though genetic factors, such as those associated with Hereditary Hemorrhagic Telangiectasia (HHT), may contribute. Patients typically present with hematuria and flank pain, necessitating a thorough diagnostic approach to differentiate from other urological conditions. Emergency management includes transcatheter renal artery embolization (RAE), favored for its minimally invasive nature, while surgical options are reserved for severe cases. This study underscores the importance of early diagnosis and a multidisciplinary approach in managing rAVMs, especially in older females presenting with hematuria, to prevent life-threatening complications.