What does four-dimensional color Doppler ultrasound mean by double kidney separation?

4-D color Doppler ultrasound means that fetal renal pelvis separation. Fetal renal separation is divided into two cases, one is a normal physiological phenomenon, two may be pathological phenomenon, that is, hydronephrosis caused. If renal pelvis separation is not more than 10 mm is normal, this situation may be related to the fetus holding urine when doing B ultrasound, and the next review may not necessarily show renal pelvis separation. There is also a case, if the renal pelvis separation exceeds 15 mm, it needs to be reviewed regularly, if the review result is normal, indicating that there is no problem, if the data after review is still greater than 15 mm, it is necessary to further check whether there is a congenital urinary tract malformation of the fetus.