Separation of the renal pelvis in babies can usually be detected by ultrasound examination during the fetal stage, which is mainly due to the behavior of the fetus in holding urine in the uterus, which causes urine to stagnate in the renal pelvis, resulting in separation of the renal pelvis. If the separation of the renal pelvis is between 10-16mm, you can continue to observe and there will not be too much problem. Most babies with separated renal pelvis can recover on their own after urination at birth, and a few babies can recover as their kidneys develop. Very few babies with separated renal pelvis need to undergo surgery, and the chances of needing surgery are generally low.