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What are the different ways to image the kidneys?

Ultrasound, CT scan, MRI, IVP (Intravenous Pyelogram), Renal scan, Renal Arteriogram are some of the commonly used methods to image the kidneys.

What are the uses of imaging studies of the kidney?

Imaging studies of the kidney are used to:
  1. Study location and size of the kidneys.
  2. To identify presence and the size of obstruction.
  3. To visualize blood supply to the kidneys.
  4. To detect and to characterize any malformations such as cysts, tumors.

What is IVP?

VP is called as intravenous pyelogram. It involves the intravenous injection of iodinated contrast material which is filtered at the glomerulus, gets concentrated within the tubules and it is finally excreted into the uterus and finally through the bladder into the urine. X –rays are taken at different time intervals from the injection of the dye. The dye usually appears from 1 to 3 minutes after the contrast material is injected. It provides an opportunity to determine the number of kidneys, their size, their configuration and if there are any filling defects. The second phase occurs between 5 minutes and it allows visualization of the ureters and the bladder.

IVP exposes one to radiation and therefore not advised in pregnant women or in very young children In addition the radio contrast can be a toxin to the kidney and specially in some people who already have some kidney of renal impairment.

How does the Ultrasound image the kidneys?

Ultrasonography represents a major advance in the non–invasive visualization of the kidney. Principal used is that of ultrasound waves generate an echo is when their passage is impeded by tissues air fluid etc. The significant differences in this impedence occurs among tissues which differ in the content of water fats minerals solids etc. The waves that are reflected are recorded as signals.

What are the uses of Renal ultrasound?

The main uses are to:
  1. Determine the size of the kidneys.
  2. To see if there is any obstruction to the flow of urine.
  3. To evaluate cysts and tumors.
Numerous cysts in both kidneys usually signifies polycystic kidney disease. Solid renal masses may signify the presence of tumor.

Is CT scan used to image the kidneys?

Certainly. Useful in imaging cysts and tumors, hemorrhage or infections.

What is Renal Arteriography?

Renal arteriography means the visualization of the Renal arteries by the injection of dye into the arteries. It is mainly used to diagnose any narrowing of the renal arteries (renal artery stenosis) which are commonly seen in advanced atherosclerosis or people who are smokers.

What is a Renal Scan?

The Renal scan involves intravenous injection of a radio nuclide labeled agent that emits radiation. Use of a scintillation camera picks up this radiation as the agent passes through the kidney. The radio pharmaceutical agents generally used are I–31 or technetium 99.The Renal Scan provides information about the blood flow within the kidney. Delayed excretion of the agent which may signify intrinsic renal disease, decreased blood flow or obstruction to the flow of urine. This is mainly used for evaluation of patients who are at high risk for adverse reaction to contrast material in whom a renal arteriogram or IVP cannot be done.

What is a Renal Biopsy?

Renal Biopsy involves taking pieces of the kidney tissue to observe under the microscope.

What are the indications for Renal Biopsy?

  1. Presence of protein &/or blood in the urine in stable patients.
  2. Unexplained acute renal failure.
  3. In renal transplantation to see if there is any rejection.

How is a renal biopsy done? Does it require general anesthesia?

The techniques usually involves the insertion of the biopsy needle under the guidance of ultrasound in the kidney Usually it does not require any general anesthesia and it can be done under local anesthesia. The procedure involves placing the patient in the prone position i.e. to lie on the stomach. The kidney is located by the ultrasound, the local anesthetic is injected and the needle is passed until it hits the kidney cortex.

Are there any contraindications for a renal biopsy?

It is contraindicated in the presence of single kidney visions where bleeding disorders or uncontrolled hypertensions.

What are the complications of a renal biopsy?

The most important complications is bleeding after the procedure or Hematuria which usually occurs in 5 to 10% of patients and usually resolves eventually in 24 to 48 hours. Rarely the bleeding is severe requiring blood transfusions.

How does a kidney biopsy look?

The pieces of kidney that are obtained are usually subject to examination by under the microscopic by doing H and E (Hematoxylyn and Eosin) stain. Special stains are used as required. Immunofloresence is done to look for deposits of antigen–antibody complexes.

Electron Microscopy helps to visualize the basement membrane in greater detail.