During the last fifteen years I have observed at close range the performance of several thousand percutaneous kidney biopsies, performed by a number of different nephrologists and radiologists, observing their techniques with considerable interest, as I evaluated the biopsy sample by examining it macroscopically and under a 20-40 X dissecting microscope, prior to allocating the tissue samples to the fixatives.  Furthermore, in the process of subsequently examining and interpreting those biopsies I have had the opportunity to gain some impression of what is likely to be an adequate biopsy, in the context of the clinical situation which has presented itself.

        This is a memoir, a recollection of impressions and ideas.  I have not taken notes, tabulated data, or done any formal study of these issues.  I have no statistical analysis to support the likely validity or probable error of any of my impressions or ideas expressed herein.  Therefore, Caveat emptor.  - Dr. Horn          

A.   Recommendations for allocation of the biopsy tissue to the three fixatives, LM, EM and IF.  B.   Observations on various approaches to the performance of the percutaneous kidney biopsy.      1. Biopsy by Silverman needle after localization by ultrasound. This traditional approach is unsurpassed when done with calmness, meticulousness, and justified confidence.     2. Biopsy by semi-automatic needle during real-time ultrasound. This technique allows prompt positioning of the needle tip at the renal capsule under direct visualization, with excellent and reproducible results, where the facility is available.

3. Biopsy after CT localization. This approach provides excellent results and is clearly indicated when localization of the kidney is difficult.    C.   How Much Tissue is Enough? The proper answer to this question is a function of the totality of the clinical situation.  D.  What size needle should be used? A delicate matter of judgment, made by the operating physician, balancing benefits of information to be obtained against possibly increased risks of a) a larger bore needle versus b) more sticks with a smaller bore needle.