MO228NATIVE KIDNEY BIOPSIES: DIAGNOCTIC VALUE AND COMPLICATIONS
Authors: Stepanov Vadim , Prokopenko Elena , Zulkarnaev Aleksei , Vetchinnikova Olga , Yankovoy Andrey 
Published: May 2021

Abstract

Background and Aims
Percutaneous renal biopsy is essential tool in nephrology but it is invasive procedure that can lead to complications, including gross hematuria, clinical significant haematoma and infection. The aim of the study was to determine the nature and incidence of PRB complications and the impact of biopsy results on treatment strategy.

Method
82 patients (male – 42, female – 40) with a median age of 43.5 (Q1; Q3 – 34;71) years, BMI 26.4 (22.9; 30.6) were included in retrospective study of all native kidney biopsies performed at our institute from January 1, 2016 to December 31, 2019. An informed consent was mandatory in all patients. The indications for biopsies were nephrotic syndrome, 24-hour proteinuria ≥ 1g, nephritic syndrome, renal failure of unknown origin. The median duration of kidney disease was 9.5 (3.0; 26.6) months, serum creatinine level - 135 (87; 197) μmol/l, eGFR (CKD-EPI formula) – 52.9 (26.6; 83.7) ml/min/1.73 m2, 24-hour proteinuria – 2.8 (1.2; 5.4) g. All biopsies were percutaneous, ultrasound-guided and were performed under local anesthesia in prone position with a 16G needle. Medications that may increase bleeding risk (anticoagulants, antiplatelet agents, and nonsteroidal anti–inflammatory drugs) was stopped before PRB. Immediately after the biopsy, bed rest and vital signs monitoring was prescribed for 12 hours. In the absence of complications, a control kidneys ultrasound was performed 24 hours after biopsy; if complications were suspected, regarding to the local protocol. We prescribed prophylactic antibiotics to the patients with a hematoma volume &gt; 100 ml. All biopsy specimens were sent to tertiary laboratory of renal pathology and evaluated by light and immunofluorescence (IF) microscopy; electron microscopy was not used in our study. Biopsy samples were considered satisfactory for diagnosis if they contained five or more glomeruli.

Results
Post-biopsy complications included gross hematuria – 19 of 82 (23.5%) patients, haematomas ≤ 100 ml – 17 (20.7%), haematomas &gt; 100 ml – 8 (20.7%), pain in the puncture site requiring the administration of analgesics – 2 (2.4%). No death, infections, bladder obstruction or nephrectomy due to biopsy complications was registered. One (1.2%) patient required blood transfusion. We identified renal arteriovenous fistula which did not require special treatment in one (1.2%) patient 2 months after PRB.
We found no differences in the incidence of post-biopsy haematomas by gender, age, or BMI. Haematomas were significantly more common in patients with higher mean blood pressure and serum creatinine levels (Fig.1, A, B).
In one case (1.2%) the biopsy was inadequate. The results of PRB were varied, including unexpected findings. IgA nephropathy was found in 23 of 81 (28.4%) patients, focal segmental glomerulosclerosis – in 21 (25.9%), membranous nephropathy – in 9 (11.1%), pauci-immune crescentic glomerulonephritis – in 6 (7,4%), lupus nephritis – in 2 (2.4%), membranoproliferative glomerulonephritis – in 2 (2.4%) - one with polyclonal Ig+/C3+ on IF and one - with monoclonal IgG kappa+, C3 nephropathy – in 1 (1.2%), AL-amyloidosis – in 2 (2.4%), light chain deposit disease – in 1 (1.2%), hypertensive nephropathy – in 1 (1.2%), diabetic nephropathy – in 3 (3.7%), tubulointerstitial nephritis – 5 (6.2%), thrombotic microangiopathy – in 2 (2.4%), diffuse nephrosclerosis – in 2 (2.4%), renal tuberculosis – in 1 (1.2%).
According to the results of the biopsy, pathogenetic treatment was first prescribed to 43 of 81 (53.1%) patients, changed – in 17 (21%), treatment remained unchanged – in 8 (9.9%) cases. Thirteen (16%) patients were referred for additional examination by a hematologist and rheumatologist.

Conclusion
Biopsy of native kidney is a high diagnostic value and safe procedure with a low risk of major complications. Treatment was changed significantly after biopsy in 74% of patients in our study.