Editorial Nephrology and the Percutaneous Renal Biopsy: A Procedure in Jeopardy of Being Lost Along the Way

The percutaneous renal biopsy (PRB) of native kidneys was introduced by Iversen and Brun (1) in 1951. Prior to this time, insight into clinicopathologic correlation was limited to information obtained through surgically obtained specimens or from evaluation at autopsy. The development of the PRB evolved from their experience with percutaneous liver biopsy using an aspiration-needle technique. Intravenous pyelography was used for localization of the right kidney (to avoid large vessels and the spleen), and the patient was biopsied in the sitting position. Unfortunately, the success of their technique was limited, with adequate tissue obtained in only 53% of biopsies (1). Concerned with the poor technical success using this technique, Drs. Robert Kark and Robert Muehrcke (2), my predecessors at RushUniversityMedical Center,made importantmodifications to the procedure (2–5). First, they performed the biopsy with the patient in the prone position and placed a sandbag under the abdomen, because they felt this would reduce the “mobility” of the kidney. Second, instead of an aspiration biopsy needle, they used a Franklin-modified Vim-Silverman needle, a precursor to the needle currently used today, which trapped the tissue in the needle and then sheared it off. In 1954, Kark and Muehrcke (2,3,5) published their experience with this “new technique,” reporting a success rate of 96% and no major complications. Kark and Muehrcke realized the value of the renal biopsy would be to provide the nephrologist with information thatwouldbe critical indiagnosis, prognosis, and guiding therapy. In their initial study, they found that the biopsy findings changed the initial clinical diagnosis in more than 50% of cases (2). Additionally, they felt that renal biopsywould provide nephrologists with the ability to follow the natural history of renal disease through repeated biopsies, define new renal diseases, and assess the effects of therapy on renal disease. Almost 60 years later, these predictions have proven true. The renal biopsy, developed by nephrologists, has become an integral part of the clinical practice of nephrology and in the research of renal disease. In fact, the development of the PRB has been considered one of themajor technological advancements that led to the establishment of nephrology as a subspecialty in 1960 (6). The success of the PRB is defined not only by the ability to attain adequate tissue for diagnosis but, equally important, the safety profile of the procedure. Throughout the years, improvements in imaging techniques and biopsy needles have resulted in the ability to obtain adequate renal tissue for diagnosis in . 95% of renal biopsies (7–11). Additionally, these technical improvements have led to increased safety of the procedure: the rate of complications resulting in death decreased from 0.12% to 0.02% during the last 50 years (7,12). In fact, during the last 20 years, death resulting from PRB of native kidneys has been an extremely rare event, with no deaths reported in a number of recent studies (13– 20). Nonetheless, despite the improved safety of the procedure, clinically significant bleeding complications do occur in 4%–7% of biopsies on average (7,12), and rates as high as 25% to . 30% have been reported in a number of recent studies despite the use of newer technologies (8,14,19,21). Although the majority of complications resolve spontaneously without the need for further intervention, in up to 9% of biopsies, the complication can be more severe and potentially life threatening, resulting in the need for intervention (7,11,12,22). In most cases, this may be simply the transfusion of blood products, but the need for more invasive intervention such as surgery or angiography and embolization, although uncommon, still occurs in up to 0.8% of biopsies even in recent reports (7,8,11,12,21). Differences in complication rates among studies can vary substantially and can be difficult to interpret because of confounding issues such as the nature of the study (prospective or retrospective), the type of imaging used (real-time ultrasound, computerized tomography, or blind biopsies after ultrasound localization), the needle type or gauge used (manual versus automated and 14, 16, or 18 gauge), and who is performing the biopsy (a few “experienced” nephrologists, many nephrologists, renal fellows, or radiologists) (7,12). Additionally, the reason for biopsy and patient mix can be important because studies that comprise highrisk patients, those with renal insufficiency, poorly controlled hypertension, or a prolonged bleeding time/coagulopathy, aremore likely to report increased complication rates (11,14,20,21,23–27). In this issue ofCJASN, Tondel et al. (28) report on the 22-year experience (from 1988 to 2010) with PRB of native kidneys from the Norwegian Kidney Biopsy Registry, which includes 26 hospitals. The 9288 percutaneous biopsies in the study represented 96% of all Section of Nephrology, Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois