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Abstract: SA-PO1095

Pre-Biopsy Lab Work and Decision Making

Session Information

Category: Pathology and Lab Medicine

  • 1502 Pathology and Lab Medicine: Clinical

Authors

  • Kohn, Orly F., University of Chicago, Chicago, Illinois, United States
  • McGill, Rita L., University of Chicago, Chicago, Illinois, United States
Background

Labwork is often ordered prior to obtaining a kidney biopsy, to assess risk of bleeding and less often ordered afterwards. We sought to determine which factors influenced the decision to monitor hemoglobin (Hb) levels after biopsy.

Methods

All kidney biopsies performed on adult patients by the Nephrology service at the University of Chicago between September 2009-October 2015 were retrospectively assessed. Pre-biopsy Hb, INR, platelet count, and platelet function assays (PFA) were collected, and the nadir Hb level over the next 14 days was assessed, when available. Median values compared with Wilcoxon test, with P<0.01 due to multiple comparisons . A multinomial regression model was used to calculate odds ratios (OR) for post-biopsy outcomes of: a) Significant drop in Hb (defined as >1.5 grams), b) Lack of post-biopsy labwork, compared to a reference outcome of available post-biopsy Hb with no significant drop. Models adjusted for age, sex, and allograft vs. native organ, with single imputation of median values for missing pre-biopsy data.

Results

Among 905 kidney biopsies, 43.8% were native and 56.2% were allografts, 49.2% were women and the mean age was 47.5±15.2 years. Hb drop > 1.5 gm occurred in 11.7%, and post-Hb data was missing for 44.6%. Labwork by outcome and OR for each post-Hb outcome are shown in the tables. Female sex, higher pre-biopsy Hb and INR were positively associated with significant Hb drop, as were lower eGFR and platelet count. Omission of the post biopsy Hb was associated with increased age, female sex, higher pre-biopsy Hb, and negatively associated with higher INR. PFA did not contribute significantly for either outcome.

Conclusion

Post biopsy Hb was more likely to be checked for allograft biopsies and patients with elevated INR, but not for several other factors that had significant associations to the risk of bleeding. Platelet function assays did not appear to contribute to decision making or blood loss. Utilization of labwork before and after kidney biopsies deserves further study.