<unk>  is diagnosed through imaging such as doppler ultrasound (DUS), computed tomography (CT), magnetic resonance imaging (MRI), and venography. The selection of the imaging modality is a step-wise process. DUS is the initial choice after clinical suspicion based on symptoms. CT and MRI are used to follow up afterwards, and if further confirmation is necessary, venography is used to confirm. Doppler Ultrasound Although its ability to detect renal vein compression is dependent on how a patient is positioned during imaging, 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. CT and MRI CT and MRI can be used afterward to confirm compression by the AA and SMA with comprehensive measurements of the abdominal vasculature. A "beak sign" can often be seen in CT scans due to the LRV compression. However, CT and MRI cannot demonstrate the flow within the compressed vein. These two modalities can be used to confirm other evidence for NCS such as back-up of blood flow into the ovarian veins. Venography If further confirmation is necessary, venography is used as the gold standard test in diagnosing<unk> . A renocaval pullback mean gradient of >3 mmHg is considered diagnostic. Although this method continues to be the gold standard, values in unaffected individuals may be vary considerably, leading to some measurements in NCS patients to be similar to those in normal individuals. This may be partly due to compensatory mechanisms in the vasculature as a result of the increased blood pressure. The invasive nature of the procedure is another consideration in comparison to DUS and CT/MRI as imaging modalities. Differential diagnosis * Pelvic congestion syndrome * Renal stones * May-Thurner Syndrome * Genitourinary malignancy * Loin pain hematuria syndrome
Nutcracker syndrome
Wieacker syndrome
MASS syndrome
Emmonsiosis
Pellegrini–Stieda syndrome
Riddoch syndrome
Aortoenteric fistula
EAST syndrome