The new Banff classification of renal transplant biopsies: a major impact on the adequacy of the cores taken

Percutaneous native renal biopsy adequacy: a successful interdepartmental quality improvement activity

BACKGROUND

An adequate renal biopsy is essential for diagnosis and treatment of medical renal disease.

OBJECTIVE

We evaluated two initiatives to improve adequacy of renal biopsy samples at our centre.

DESIGN

Retrospective determination of renal biopsy adequacy.

SETTING

Queen Elizabeth II Health Sciences Centre.

PATIENTS

Patients undergoing medical renal biopsies.

MEASUREMENTS

Renal biopsy adequacy.

METHODS

The first initiative was to restrict the performance of biopsies to a smaller group of radiologists and to include a comment on biopsy adequacy in every pathology report. The second initiative was to introduce on-site adequacy assessment by a medical laboratory technologist. Native renal and allograft biopsy adequacies were calculated for three periods: 1) baseline, October 2005 to September 2006; 2) after implementation of the first initiative, January 2007 to September 2011; and 3) after implementation of the second initiative, October 2011 to September 2012. A subset of native renal biopsies was examined to determine if there was a relationship between adequacy and number of passes.

RESULTS

The percentages of adequate native renal biopsies during the first, second, and third periods were 31%, 72% and 90%, respectively. This represents a significant increase (40%, p < 0.0001) in adequacy following the first initiative, and another significant increase (18%, p = 0.0003) following the second initiative. The percentages of adequate renal allograft biopsies during the first, second, and third periods were 75%, 56% and 69%, respectively. These changes in adequacy were not statistically significant. In the subset of native renal biopsies examined, a biopsy comprising more than three cores was not associated with increase in adequacy.

LIMITATIONS

The most important limitation is the lack of generally accepted and applied adequacy criteria limiting generalizability of our findings.

CONCLUSIONS

Restricting the performance of biopsies to subspecialist operators, including an adequacy statement in the renal biopsy report and on-site adequacy assessment were effective in significantly improving native renal biopsy adequacy. This improvement appeared unrelated to an increase in the number of passes taken with a biopsy needle. Neither initiative improved the low adequacy of allograft biopsies.

Renal transplant biopsy specimen adequacy in a paediatric population

Updated guidelines on the diagnosis of acute allograft rejection including criteria for biopsy specimen adequacy were published in 1999. We sought to determine the adequacy of specimens in paediatric transplant patients and identify factors influencing adequacy. All renal transplant biopsies performed between 1998 and 2003 were classified as adequate (n =25), minimal (n =19) or inadequate (n =27) in accordance with the Banff 97 criteria, and the histological diagnoses were documented. The effect on specimen adequacy of grade of operator, method of sedation, age of child, needle gauge, number of cores and total core length was then investigated. Overall, a minimal or adequate specimen was obtained in 62% of cases. No histological diagnosis could be made in 30% of all specimens, just over half of which were inadequate. Higher rates of rejection were found in adequate (52%) than inadequate (33%) samples. The grade of operator (p =0.498), the age of the child at the time of biopsy (p =0.815) and type of sedation (p =0.188) did not affect adequacy. More than one core was obtained in 38 (54%) cases, and this was significantly associated with specimen adequacy (p <0.0005) as was longer total core length (p =0.002). Clinical features in isolation are not sufficient for the diagnosis of acute allograft rejection. Renal biopsy remains the gold standard and relies on adequate specimen collection. Our data shows that specimen adequacy according to the Banff 97 guidelines is achievable in children and that more than one core at the time of sampling significantly improves this achievement. Adequate sampling reduces the risk of an inconclusive histological diagnosis.