Nutcracker phenomenon: An unusual presentation of acute aortic dissection
A 49-year-old previously healthy woman with no history of trauma presented with intermittent gross hematuria and mild left flank pain of five days' duration. The patient described that her intermittent pain was aggravated by postural change and it gradually waned. The patient had no apparent respiratory, gastrointestinal or voiding symptoms. Her past medical history including hypertension, atherosclerosis and congenital diseases was non-contributory. She was afebrile and her physical examination findings were almost normal. Her blood pressure was 182/66mmHg. Urinalysis demonstrated 20–29 red blood cells per high-power field, 10–19 hyaline casts per field of vision and a sterile culture. Urine cytology was negative for malignancy. Laboratory examinations were within normal limits, except for the elevated C-reactive protein levels of 4.64mg/dL (normal, <0.30mg/dL). Ultrasonography and excretory urography did not reveal any definite structural abnormality in the urinary tract.\nWhen the patient visited our outpatient clinic the next day, urinalysis showed dark urine containing numerous red blood cells without dysmorphic changes. Cystoscopy revealed bleeding from the left ureteral orifice. Contrast-enhanced computed tomography (CT) demonstrated aortic dissection originating just distal to the left subclavian artery and continuing into the bilateral common iliac arteries with a re-entry site in the abdominal aorta, compatible with acute Type B aortic dissection. No apparent branch vessel ischemia was observed. The patient was transferred to the intensive care unit in order to provide medical treatment, and prompt attention was paid to stabilizing the patient by reducing blood pressure.\nOn the retrospective review of CT scans, the arterial phase demonstrated the left renal artery originating from the true lumen of the aorta and no apparent renal ischemia []. The venous phase showed compression of LRV between the enlarged aorta and SMA with distal dilatation []. A prominent left gonadal vein, implicating formation of collateral circulation, was also observed. Three-dimensional CT imaging demonstrated the compressed LRV and development of collaterals []. After the possibility of more common renal conditions such as tumors, urolithiasis and other medical renal diseases was excluded, we made a final diagnosis of NCP due to acute aortic dissection, explaining the gross hematuria. Invasive venography to measure the pressure gradient between LRV and the inferior vena cava was not performed.\nDuring the following month, her clinical symptoms subsided and urinalysis abnormalities normalized. However, one month after the diagnosis, CT findings of LRV compression and left gonadal vein dilatation remained unchanged.