What exactly is a renal ultrasound study?

Using sound waves . Renal us uses sound waves to pass through the tissues to make black and white images of the kidney tissue and urinary bladder. It is painless and uses no dye. It takes about 20 minutes to perform and is interpretted by a licsenced doctor called a radiologist.
Radiology test. A renal ultrasound is a diagnostic radiology test performed by an ultrasonographer or radiologist. It uses sound waves at various frequencies to create pictures of internal organs and other parts of the body. The benefit of ultrasound is it is non-invasive and does not expose the patient to radiation.

Related Questions

What instructions will I recieve prior to the renal ultrasound study?

See below. Generally speaking there are no fasting requirements for renal ultrasound however centers differ in their requirements. Read more...
Show up on time. There are no dietary restrictions for a renal sono. No special prep is required but you may be asked to refrain from eating breakfast before the examination if a survey of the abdominal aorta and renal arteries is planned. Read more...

What exactly are the renal ultrasound limitations in the evaluation of urinary tract?

Not pyelonephritis. Renal ultrasound can not detect pyelonephritis unless there is appreciable swelling of part or all of the kidney. It is excellent for demonstrating kidney cysts, hydronephrosis or kidney obstruction. Will demonstrate large and obstructing kidney stones but can and will miss small kidney stones smaller especially smaller than 3mm. Read more...
Many. Ultrasound can only "see" changes to kidneys that alter the appearance of the kidneys themselves. It cannot see laboratory abnormalities. It can see altered blood flow. It can see when the kidneys are blocked (hydronephrosis), among other disorders. As with any radiology modality, ultrasound is used in conjunction with other lab tests and your doctor's expertise. Read more...

Why exactly would I need a 'renal ultrasound' for high blood pressure at 21?

It is indicated. As having high blood pressure is clearly abnormal in a 21 year old. Your doctor will order blood tests and kidney imaging to rule out secondary causes of hypertension. Read more...
TO LOOK FOR STENOSIS. Narrowing of renal artery can cause htn. In a young person noy uncommon to get renal doppler to look for signs of narrowing. Read more...

I have a renal ultrasound in 2 weeks. Radiologist noted hydronephrosis on my CT scan from 12/26. Will this study confirm the CT result?

Yes. Seems like your us was done 2 weeks ago. You should have the results. If the hydronephrosis developed after us then it will not show on ct scan. Read more...
Yes. Ct likely done for pain, possibly for a kidney stone which may or may not have passed. Us will show if hydronephrosis has resolved. This would be good management. Us not necessary to confirm ct diagnosed hydronephrosis if due to non-calculus (stone) obstruction like at upper ureter. Such obstruction would require a mag3 nuclear scan to quantify obstruction and need for possible corrective surgery. Read more...
Yes. It may also see differences in the size of the renal collecting system compared to the ct which might help diagnose if the hydronephrosis is stable or changes over time. Read more...