The signs and symptoms of NCS are all derived from the outflow obstruction of the left renal vein. The compression causes renal vein hypertension, leading to hematuria (which can lead to anemia) and abdominal pain (classically left flank or pelvic pain).
NCS symptoms arise from the obstruction of the left renal vein's exit. This blockage causes elevated blood pressure in the renal vein, ultimately causing hematuria (potentially leading to anemia) and abdominal pain (commonly located in the left flank or pelvis).