important study looked at kidney biopsy metrics and adequacy that might be
important for the Nephrology world.
To understand adequacy and variation of kidney biopsies
done by nephrologists and radiologist, the investigators collected
adequacy-associated data (%cortex, glomeruli, arteries, length) from
consecutive native and allograft kidney biopsies over a 22-month period. In
total, 1332 biopsies (native: 873, allograft: 459) were included, 617 obtained
by nephrologists, 663 by radiologists, and 559 with access to on-site division.
In summary, proceduralists with access to on-site evaluation had significantly
lower inadequacy rates and better division of tissue for light microscopy (LM),
immunofluorescence, and electron microscopy than those without access to
on-site evaluation. Radiologists in this large study were significantly less likely to have access
to on-site evaluation than nephrologists. On multivariate analysis for native
kidney biopsies, the effect of having a radiologist perform the biopsy and
having access to onsite division were both significant predictors of obtaining
greater calculated amount of cortex for LM. Despite the trend for radiologists to
obtain more tissue in general, biopsies from nephrologists contained
a greater percentage of cortex and were more likely to be
considered adequate for LM (native kidney inadequacy rate for LM: 1.11% vs.
This is the by far the largest data analysis that could
provide useful feedback and/or benchmark data to kidney biopsy proceduralists.
It also provides objective data on the critical role of on-site evaluation and
of tissue for obtaining adequate biopsy tissue appropriately
divided for LM, IF, and EM. As treating nephrologists, we feel this is important
and can make a major difference in diagnosis and treatment.
Interestingly, in this study, for native kidney biopsies,
the effect of having a radiologist perform the biopsy and having access to
on-site division were both significant predictors of obtaining a greater
calculated amount of cortex for LM. Despite the trend for radiologist obtaining
more tissue in general, biopsies from nephrologists had a greater percentage of
cortex and were more likely to be considered adequate for LM. Why is that?
Cortex obtaining is critical and getting that sample is importantly taught to
us as fellows and attendings doing kidney biopsies. If my differential is AIN
and ATN, then the cortex-medulla might not make a big difference but for a GN
diagnosis, getting a cortex and having enough sample for LM, IF and EM is
In this study, the radiologists’ inadequate for LM rates
for native kidney biopsies appeared be independent of on-site evaluation and authors
suggest that this could be due to patient selection (with more challenging
biopsies sent to radiology), could represent a long-term effect of lack of
on-site evaluation, division, and feedback from pathologists, and/
or may be due to other factors. Sonogram assisted vs CT scan guided was not discussed
in this study.
This is an important study and a reminder to the
Nephrology world to continuing doing kidney biopsies as nephrologists. It is critical
to get adequate samples and nephrologists do a better job at that. Having
onsite evals of adequacy also allows for this to be better. Educating the
radiologists on this important topic is also critical if Nephrologists are not
going to be performing this procedure anymore in near future. An article in a
high index radiology journal is much needed to raise this important issue.