What are the signs and symptoms of renal artery aneurysm in patients, particularly those with a history of hypertension or kidney disease, and in women or individuals with fibromuscular dysplasia (FMD) or other vascular diseases?

Signs and Symptoms of Renal Artery Aneurysm

Clinical Presentation

The majority of renal artery aneurysms (RAAs) are asymptomatic, discovered incidentally during imaging for other indications, with approximately 75% of patients having no symptoms at presentation. 1

Asymptomatic Presentation

• Most RAAs (75%) are discovered incidentally during imaging studies performed for unrelated reasons 1
• Asymptomatic aneurysms typically remain stable, with a low growth rate of 0.06-0.086 mm per year 1, 2
• The absence of symptoms does not correlate with aneurysm size, as even aneurysms >2 cm may remain asymptomatic 3

Symptomatic Presentations

When symptoms do occur, they manifest in several distinct patterns:

Hypertension-Related Symptoms

• Difficult-to-control hypertension is the most common symptomatic presentation, occurring in approximately 10% of patients with RAAs 1
• Renovascular hypertension results from renin-mediated mechanisms when the aneurysm contributes to renal artery stenosis or compromises renal perfusion 4
• Hypertension may be particularly severe or refractory to standard medical management 5
• New-onset hypertension in young women (ages 25-50) should raise suspicion for RAA, especially when associated with fibromuscular dysplasia 4, 6

Pain Syndromes

• Flank pain occurs in approximately 6% of symptomatic patients 1
• Abdominal pain presents in approximately 2-8% of patients 1, 5
• Pain may indicate aneurysm expansion, thrombosis, or impending rupture 5

Hematuria

• Gross hematuria occurs in approximately 4-9% of patients and may indicate rupture into the collecting system 1, 5
• Hematuria represents a concerning acute symptom requiring urgent evaluation 5

High-Risk Populations and Associated Conditions

Fibromuscular Dysplasia (FMD)

• RAAs are strongly associated with FMD, particularly in young to middle-aged women 4, 6
• FMD characteristically involves the middle and distal two-thirds of the main renal artery, unlike atherosclerotic disease 4, 6
• The classic "string of beads" angiographic appearance of medial fibroplasia (80-85% of FMD cases) may coexist with aneurysmal changes 4, 6
• Fusiform aneurysmal dilation commonly occurs distal to focal FMD stenosis 7

Women of Childbearing Age

• Premenopausal women face increased risk of aneurysm rupture during pregnancy, particularly with noncalcified aneurysms >2 cm 4
• This population requires heightened surveillance and lower threshold for intervention 4, 5

Patients with Systemic Vascular Disease

• Multiple RAAs occur in 18% of patients 2
• 24% of patients with RAAs have concomitant aneurysms in other splanchnic or iliac vessels, indicating systemic arterial disease 2
• Atherosclerotic disease accounts for approximately 90% of renovascular stenotic lesions but is less commonly associated with true aneurysms 4

Anatomic Characteristics That Influence Presentation

• Most RAAs are unilateral (96%), right-sided (61%), saccular (87%), and calcified (56%) 1
• The majority are located at the main renal artery bifurcation 2, 5
• Mean diameter at presentation is 1.5-1.6 cm 1, 2
• Branch involvement may lead to segmental renal infarction and focal symptoms 7

Acute Complications (Rare but Critical)

Rupture

• Aneurysm rupture is extremely rare in contemporary series, with rupture rates approaching zero in observed patients 1, 3, 2
• When rupture occurs, it may present as retroperitoneal hemorrhage or rupture into the renal pelvis causing massive hematuria 7
• Noncalcified aneurysms >2 cm in premenopausal women carry the highest rupture risk 4

Thrombotic Complications

• Thrombosis of distal branches may occur, particularly with fusiform aneurysms associated with FMD 7
• Acute thrombosis can cause renal infarction and acute severe hypertension 7
• Dissecting aneurysms are particularly prone to thrombosis and represent the most damaging subtype 7

Key Clinical Pitfalls

• Do not assume calcification protects against growth or rupture—calcified aneurysms grow at the same rate as noncalcified ones (0.086 cm/year) 1
• Do not overlook the systemic nature of the disease—screen for aneurysms in other vascular beds, particularly in patients with FMD 6, 2
• Severe hypotension or azotemia provoked by ACE inhibitors or ARBs suggests hemodynamically significant renal artery stenosis, which may coexist with RAA 4, 6
• In patients with difficult-to-control hypertension and RAA, repair cures hypertension in only 32% and improves it in 26%, so realistic expectations must be set 1