The separation of the fetal left renal collecting system refers to the fetal ultrasound examination when the interval between the left kidney and the ureteral connection is found to become larger, which usually indicates that there is stored urine in the left renal system, and the degree of separation can be evaluated according to the size of the anterior and posterior diameters of the renal pelvis, which can be dealt with separately. 1. renal pelvis separation <10mm: it is usually a physiological separation, which is a common phenomenon during growth and development and may be caused by the fetus holding urine, usually It will disappear with fetal development or after birth by itself, and can be rechecked by ultrasound after a week. If there is no significant enlargement, no special treatment is needed for the time being; 2. Renal pelvis separation ≥10mm: the degree of separation is more serious at this time, especially if it is accompanied by thinning of the renal cortex, and the risk of fetal urinary malformation is great, and further examination for organic lesions is needed, and amniocentesis or non-invasive DNA is recommended to check whether the chromosomes are normal. We should pay attention to regular maternity screening, keep emotionally relaxed and happy, reduce anxiety and stress, pay attention to rest, avoid exposure to tobacco, alcohol, forbidden drugs and other potentially teratogenic chemicals, especially stay away from second-hand smoke, and eat a reasonable diet and enhance nutrition to help the healthy development of the fetus.