Women usually undergo a 4D ultrasound for major abnormalities at about 24 weeks of pregnancy. If the fetus is found to be separated from both kidneys at this time, but the width of the separation is less than 1cm or less, it is often considered to be a physiological separation manifestation caused by the fetus holding urine. So at this time, we can not do any treatment for the time being, but wait for half a month and then review the 4D ultrasound to see if the separation of both kidneys has increased or decreased. If the separation of both kidneys is significantly reduced or disappeared, it means it is a physiological change, but if the separation of both kidneys is significantly increased and it is more than 1cm, then it should be considered as an abnormality caused by fetal double kidney malformation, and usually need to induce abortion to terminate the pregnancy.