Not long ago, a female patient with left lower extremity edema presented to our department. According to the customary thinking, we considered that she might have edema of the limb due to deep vein thrombosis of the lower extremity. However, ultrasound examination of the patient did not reveal any deep vein abnormality. Later, we performed a series of tests to rule out the possibility of cardiogenic, nephrogenic, and lymphedema. So, what kind of strange disease did she have? In fact, she did not have a difficult disease, but a venous system disease that is easily overlooked – namely cockett syndrome, also called iliac vein compression syndrome. The pathology that constitutes this? s pathology is based on the normal iliac arteriovenous anatomical relationship. Studies have shown that in about three-quarters of the population, the right common iliac artery crosses the left common iliac vein, and this, combined with the physiological protrusion of the lumbosacral spine, places the iliac veins in an anatomical position of anterior compression and posterior crowding. Sometimes the compression of the iliac vein can be completely asymptomatic, and sometimes it can manifest as chronic venous insufficiency due to long-term venous hypertension, such as edema, superficial varicose veins and other stasis symptoms. In addition, once combined with trauma, surgery, childbirth, or prolonged bed rest, iliac-femoral vein thrombosis can occur, manifesting as acute swelling, pain, and compensatory dilation of superficial veins in the lower extremities. Due to the influence of pelvic organs, ultrasonography sometimes cannot detect the disease, while venography can improve the positive rate of diagnosis and is the most reliable method to diagnose the disease. Later, we performed venography on the patient. As a result, we found that the patient’s contrast density was reduced at the left common iliac vein into the inferior vena cava, and there was the formation of collateral circulation, so the diagnosis of cockett was established. The diagnosis was clear, and Director Zhang Lei performed iliac vein stenting for the patient, and the procedure was successful with good iliac vein reflux on re-imaging. The patient’s edema decreased quickly after surgery and he was discharged from the hospital. This case inspires us that in clinical work, if we encounter a patient with lower limb edema, we should consider more considerations, especially if the etiology is not exact, and we should not ignore cockett syndrome so as to avoid any missed diagnosis or misdiagnosis.