Physicians use renal ultrasounds to examine the condition of the kidneys and related organs, such as the ureters and bladder, states Johns Hopkins Medicine. Renal ultrasounds detect the size, location and shape of these organs, and they reveal tumors, cysts, obstructions and infections.
Renal ultrasounds can detect fluid retention around the kidneys and stones in the kidneys or ureters, reports Johns Hopkins Medicine. Renal ultrasounds are useful tools when physicians need guidance in placing needles in or near the kidneys. Doctors rely on ultrasounds when doing biopsies of kidney tumors, draining kidney cysts or abscesses, and inserting drainage tubes. Renal ultrasounds are also used to measure blood flow to the kidneys via the renal arteries and veins. Additionally, they are used to examine a new kidney after a kidney transplant.
During a renal ultrasound, a transducer sends sound waves through the body towards the organ being examined, explains Johns Hopkins Medicine. The waves bounce off the organs and bones at different rates, and the transducer interprets this data as indicating different kinds of tissue. Renal ultrasounds are good alternatives to CAT scans for pregnant women and patients with allergies because ultrasounds do not require the injection of contrast dyes into the body.
Before the procedure, clear gel is applied to the skin to allow the transducer to move smoothly and to eliminate air between the skin and the transducer. There are no specific preparations that a person needs to do before the test. However, children may be required to fast for several hours prior to a renal ultrasound.