Renal Biopsy

 Indications for performing this procedure:   Renal biopsies should only be considered when less invasive preliminary tests, such as CBC, serum biochemistry panel, U/A, etc. and assessment of clotting ability are performed.  Renal biopsies are necessary to differentiate glomerular amyloidosis from glomerulonephritis. This is an important diagnostic finding since amyloidosis is a progressively fatal disease and glomerulonephritis may have a variable outcome with extended periods of stable renal function.  Therefore, biopsy information is important in obtaining a prognosis and formulating a treatment plan. 

Surgical methods:  The best way to perform a renal biopsy is during a laparotomy when both kidneys may be visualized.  A surgical wedge biopsy (2 mm wide by 0.75 to 1 cm long by 3 to 4 mm deep) will be necessary for adequate glomeruli for diagnosis and any immunofluorescent/immunohistochemistry techniques or electron microscopy.  Careful sampling is necessary to avoid major vessels and nerves in the renal pelvis.  A Congo red stain should be requested to detect amyloid deposits; the amyloid will appear green and birefringent when stained with Congo red and viewed under polarized light.  Other renal biopsies techniques include the percutaneos  samples obtained using the keyhole technique or by ultrasonographic guidance. 

Important consideration:  It is very important to consult with the histopathology laboratory before any biopsy procedure to insure the necessary tissue and sample amounts are obtained and correct fixatives are used.

Complications:  Hemorrhage is the major potential problem after a renal biopsy.  Assessment of clotting ability and platelet count should be completed before a renal biopsy.  Most animals will have microscopic hematuria for about 2 days after the procedure (overt hematuria is not uncommon).  Severe hemorrhage is uncommon and usually associated with faulty biopsy technique.

Contraindications:

 

For more information:

Textbook of Veterinary Internal Medicine: Diseases of the Dog and Cat, 5th edition. 2000.Ettinger and Feldman. Chapter 170.