The nutcracker syndrome (NCS) results most commonly from the compression of the left renal vein (LRV) between the abdominal aorta (AA) and superior mesenteric artery (SMA), although other variants exist.

There is a wide spectrum of clinical presentations and diagnostic criteria are not well defined, which frequently results in delayed or incorrect diagnosis.

[3] This condition is not to be confused with superior mesenteric artery syndrome, which is the compression of the third portion of the duodenum by the SMA and the AA.

This can result in pelvic pain and also GI tract irritation leading to bloating, abdominal fullness, constipation and/or diarrhea.

[8] NCS can also be due to other causes such as compression by pancreatic cancer, retroperitoneal tumors, and abdominal aortic aneurysms.

[8] Patients with NCS usually have a low BMI, as this can lead to a narrower gap between the SMA and the AA for the LRV.

[12] Although its ability to detect renal vein compression is dependent on how a patient is positioned during imaging and technician knowledge and skill, DUS is recommended as an initial screening tool as it has a high sensitivity (69–90%) and specificity (89–100%).

DUS measures the anteroposterior diameter, and a peak systolic velocity at least four times as fast as an uncompressed vein is indicative of NCS.

[6] CT and MRI with contrast can be used afterward to confirm compression by the AA and SMA with comprehensive measurements of the abdominal vasculature.

[11] In contrast, more severe symptoms such as reduced renal function, flank pain, and anemia are managed with surgical interventions.

[11] Conservative management is advised in children as further growth may lead to an increase in tissue at the fork between the SMA and AA, providing room for the LRV to pass blood without obstruction.

[12] Following catheterization, venography is done to visualize the vasculature and can provide confirmatory diagnosis of NCS prior to stenting.

Many surgeons no longer recommend stenting the renal vein for the high risk of migration and lack of long term symptom relief.