A rare cause of chronic flank pain – posterior nutcracker syndrome

Clinical History

A 54-year-old female patient presented with a history of left flank pain for several years, worse in the past year. She reported pain increasing on standing and walking and relieved with rest. Her urine routine examination and ultrasound abdomen were normal. The patient was referred for CT abdomen.

Imaging Findings

The left renal vein was seen coursing behind the aorta and joining the azygous vein at the level of L1. The left gonadal vein was prominent with tortuous prominent veins in the left hemipelvis and parametrium. These veins were seen communicating with the left internal iliac vein. Prominent veins were also noted in the left inguinal canal. The left kidney appeared normal in size, shape and contour with normal excretion of contrast.

Discussion

Nutcracker syndrome, first described by De Schepper, refers to compression of the left renal vein between the aorta and superior mesenteric artery [1]. It is an unusual cause of haematuria. Two types have been described. The anterior nutcracker syndrome occurs due to compression of the left renal vein as it passes between the superior mesenteric artery and the aorta, leading to impaired blood flow and congestion with subsequent formation of venous collaterals [3].
Posterior nutcracker syndrome occurs due to compression of retroaortic left renal vein as it courses between the aorta and the vertebral column [2]. The main presenting symptom is haematuria with or without left flank pain. Our patient did not have haematuria.
Formation of varicosities in the gonadal veins can lead to gonadal vein or pelvic congestion syndrome where the classical history would be flank pain exacerbated by sitting, standing, or walking. The extensive venous collaterals in the pelvis and parametrium in our patient could very well explain the typical complaint that she presented with.
The treatment options include close surveillance, endovascular stents or surgery; the latter two are needed only when there is persistent or severe flank pain or gross haematuria [4, 5]. Our patient was treated conservatively and showed significant improvement in her symptoms on follow-up.
Doppler study may show turbulent flow in the posterior left renal vein behind the aorta. Contrast enhanced CT abdomen and MRI with MR angiography are currently recommended in the non-invasive diagnostic work-up of patients with unexplained haematuria and flank pain [5].
Nutcracker syndrome is a rare condition and radiologists need to have a high index of suspicion in patients who present with haematuria. CT and MR angiography play a valuable role in the diagnosis.

Differential Diagnosis List

Final Diagnosis

Posterior nutcracker syndrome.

URL:	https://www.eurorad.org/case/12563
DOI:	10.1594/EURORAD/CASE.12563
ISSN:	1563-4086