4D ultrasound is a normal result if it shows that both kidneys of the fetus are visible. 4D ultrasound is referred to as macroscopic ultrasound, which can clarify whether the fetus has any abnormal development of internal organs. A normal human being has two kidneys, so if a 4D ultrasound is done to examine the fetus, both kidneys can be seen to be completely normal and there is no need to worry too much. If there is a congenital developmental abnormality, it may result in the absence of one side of the kidney or a significant reduction in the size of one side of the kidney. If the fetus has abnormal development of the urinary system, it may lead to a significant separation of the renal pelvis, and when there is an abnormality in the 4D ultrasound, it is important to visit the prenatal clinic promptly.