A 63-year-old former construction worker presents to his physician complaining about "dark urine" for the past 3 days. He also complains about left flank pain since this morning, which has made him come to the clinic. His past medical history is notable for hypertension, but despite being on antihypertensive treatment, his blood pressure remains uncontrolled. The patient also smokes one to two packs per day for the last 40 years, but he does not drink alcohol or use illicit drugs. He has no other medical problems. He is afebrile, his heart rate is 102 bpm and his respiratory rate is 14 bpm. His blood pressure is 150/95 mmHg. Laboratory findings are normal, except for a hemoglobin level of 9.5 g/dl and a hematocrit level of 32%. Upon further evaluation a contrast-filled outpouching was found in the course of the left renal artery.
The correct answer is: C. Ruptured RAA (Renal Artery Aneurysm)
This patient complains of acute onset left flank pain and gross hematuria ("dark urine"). These findings, in addition to his persistent hypertension and the abnormal hematocrit/hemoglobin levels, indicate that he is possibly suffering from a ruptured renal artery aneurysm (RAA). RAAs account for approximately 25% of all visceral artery aneurysms, the prevalence in the general population is between 0,01-1% and are usually solitary lesions. They are often diagnosed incidentally in the course of investigation for hypertension, hematuria or abdominal pain, as in this patient.1 Although most cases are asymptomatic, symptoms may arise due to aneurysm rupture, embolization of peripheral vascular bed, or arterial thrombosis.
About 70% of RAAs are associated with arterial hypertension, which has been attributed to increased renin levels. RAAs causes include but are not limited to atherosclerosis, trauma,2 inflammatory diseases, connective tissue diseases, fibromuscular dysplasia, etc.3 Although the gold standard method for diagnosing a RAA is angiography, computed tomography (CT) and magnetic resonance imaging (MRI) are most commonly used as they are essential for an accurate evaluation of the size, location and characteristics of the aneurysm.
Indications for RAA treatment include hemorrhage, uncontrolled hypertension, pain, progressive enlargement, and presence of an arteriovenous fistula, size >2 to 2.5 cm, or >1 cm in a female of childbearing age. Currently, endovascular repair is the intervention of choice in elective or emergent circumstances.1 Although autosomal dominant polycystic kidney disease may present with flank pain, hematuria and hypertension, bilateral enlarged kidneys would be expected on imaging studies rather than a contrast filled outpouching in the course of renal artery (Answer A).
Renal cell carcinoma could be a possible answer, as the patient has a smoking history that could contribute to development of renal cell carcinoma. The gross hematuria and left flank pain could be attributed to renal carcinoma as well. However, the decreased levels of both hemoglobin and hematocrit usually are not present in a renal cell carcinoma. Renal cell carcinoma has been associated with ectopic production of erythropoietin causing secondary polycythemia. Thus, in the absence of fever, anorexia, and weight loss, RAA is more likely to be the cause of patient's symptoms than malignancy (Answer B).
Transitional cell carcinoma of the bladder usually presents with painless hematuria. Although the patient's smoking history is a major risk factor for this type of tumor, the persistent hypertension and the sudden onset of flank pain are not common manifestations of transitional cell carcinoma (Answer D).
Although fibromuscular dysplasia can be the underlying cause of RAA formation, it is more common in young females than older males (female to male ratio 3:1). Imaging studies in a patient with fibromuscular dysplasia would have shown a "string of beads" pattern, not a solitary contrast-filled outpouching in the route of the renal artery. Also, hematuria cannot be explained by this disease (Answer E).
Educational Objective
Renal artery aneurysm (RAAs) are focal dilations of the renal artery and/or of its branches. Most RAAs are discovered incidentally during unrelated abdominal imaging or angiography.1 When patients do present with symptoms, they are usually in the form of flank pain and hematuria that can range from mild microscopic hematuria to gross hemorrhage leading to hemodynamic instability.1,2 Health care practitioners should be aware of life-threatening causes of gross hematuria and appropriate evaluation.
References
- Wason SEL, Schwaab T. Spontaneous rupture of a renal artery aneurysm presenting as gross hematuria. Rev Urol 2010;12:e193–e196.
- Eskandari MK, Resnick SA. Aneurysms of the renal artery. SeminVasc Surg 2005;18:202–8.
- Dulabon LM, Singh A, Vogel F, Moinzadeh A. Intrarenal pseudoaneurysm presenting with microscopic hematuria and right flank pain. Can J Urol 2007;14:3588–91.
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