Why, when and how to perform percutaneous renal biopsies
Can you assess when this diagnostic procedure is best indicated?
Oct 01, 2010
A colleague in private practice asked my opinion about the likely benefit of obtaining an ultrasound-guided percutaneous needle biopsy of the kidney of a 15-year-old spayed female domestic shorthaired cat. He said evaluation of a serum chemistry profile, hemogram and urinalysis revealed findings (isosthenuria, intrarenal azotemia, hypoproliferative anemia, acidemia, hyperphosphatemia) consistent with idiopathic chronic renal failure (CRF). No evidence of bacterial urinary tract infection was noted. The cat's systolic blood pressure was increased. The cat's owners requested the veterinarian pursue additional diagnostics, especially if they could help in devising a treatment for the renal failure and prolong the cat's life.
Ultrasonographic evaluation of the cat's kidneys by a board-certified radiologist revealed that both kidneys were reduced in size. Uroliths were not observed. An advantage of ultrasonography is the biopsy needle can be guided into portions of the kidney so as to minimize the risk for damage to large renal vessels and the renal pelvis. In addition, the kidney can be scanned for evidence of significant post-biopsy hemorrhage.
In cases in which renal biopsy permits establishment of a specific diagnosis, knowledge of the etiology facilitates formulation of a specific therapy designed to eliminate or control the underlying cause of renal disease. Although the specific therapy may not alter existing lesions, it may prevent further damage to nephrons and adjacent structures. In situations in which the light microscopic, immunofluorescence or electron microscopic changes do not indicate a specific diagnosis, the character and distribution of lesions may allow one to determine whether the disease process is likely to undergo partial or complete resolution, remain static or become progressive and irreversible. Such information may be especially helpful when evaluating patients with acute renal failure associated with declining renal function and/or oliguria despite appropriate specific and supportive therapy. In some patients, properly performed serial biopsies of the kidney also may be used to monitor therapeutic efficacy, morphologic resolution of the disease or progression of renal disease.