The kidneys primary function is to remove a type of waste called urea from the blood. Ureas is produced when foods containing protien — meat, poultry, and certain vegetables — are broken down in the body.
Urea, together with water and other waste substances, form urine.
A kidney ultrasound may be used to assess the size, location, and shape of the kidneys and related structures ureters and bladder. The Ultrasound can detect cysts, tumors, abscesses, obstruction, fluid collection, and infections. Kidney stones — calculi of the kidneys and ureters — can also be detected.
An ultrasound of the kidneys may also be performed to assist in obtaining tissue samples, to place draining tubes, and even to determine blood flood through the renal arteries and veins.
In general, an ultrasound is an easy, non-invasive, painless proceedure. The kidney ultrasound doesn't require any specific preparation such as fasting or sedation. Drinking clear fluids at least one hour before the appointment and restrict emptying the bladder are sufficient preparation.