It is of  almost same size, ultrasonography measures only approximate size.ultrasonography done on the same day by two different ultrasonologist may have 1-2 mm of variation. For small stones general measures are Avoid high oxalate&uric acid containing foods, adequate water at regular intervals. Drugs like mixture of potassium magnesium citrate mixed with glass of water thrice daily in doses of 15 ml every time may help in passing out the stone