A 2.15-fold widening of the posterior extension at the left renal vein pinch angle is usually referred to clinically as the nutcracker phenomenon, also known as nutcracker syndrome. It is a condition in which the left renal vein crosses the angle between the abdominal aorta and the superior mesenteric artery or the gap between the abdominal aorta and the spine on its way to the inferior vena cava and is compressed, causing a series of symptoms such as hematuria, proteinuria, and left lower back and abdominal pain. It is most common in taller, thinner adolescents and is rare in those over 30 years of age. If the patient found that the left renal vein pinch angle at the posterior stretch widened 2.15 times, it is recommended to go to the regular hospital in time, under the guidance of the doctor to standardize the treatment.