If the stones in the urinary system are not detected by ultrasound, further CT or imaging of the urinary system is needed to clarify them, because sometimes intestinal distention is more obvious and can interfere with ultrasound, which can lead to stones in the middle part of the ureter not being easily detected, or because the patient cannot hold urine or does not hold urine well, which then leads to a missed diagnosis, and further imaging or CT examination. CT of the urinary system can see more clearly whether there are stones in the urinary tract, and it is not affected by intestinal gas or holding urine, but thin layer CT scan is needed because when a normal CT scan is performed, the layer spacing between the two CT layers is about 7mm, and then there is a possibility that stones below 6mm may be missed in the normal CT during the examination, and the layer spacing of thin layer CT is about 2.5mm, and usually no leakage occurs. Urological imaging can also detect stones that cannot be detected by ultrasound, but it takes longer and some patients may be allergic to the contrast agent, and patients with poor kidney function cannot undergo imaging.