Thirty-four studies (9,474 patients, the number of biopsies per study ranged from 77 to 1,120) were included in the review. There was one randomised controlled trial, thirteen prospective and twenty retrospective studies. Out of a possible quality score of five, three studies scored two, 17 scored three, 12 scored four and two scored five.
The overall rate of macroscopic haematuria was 3.5% (95% CI 2.2 to 5.1; 30 studies, 8,042 biopsies) and erythrocyte transfusion was required in 0.9% of the biopsies (95% CI 0.4 to 1.5; 32 studies, 9,456 biopsies). Statistical heterogeneity was high for both outcomes with Ι² of 92% for macroscopic transfusion and 84% for erythrocyte transfusion. The rate of perinephric haematoma was 11.6% (95% CI 7.0 to 18.4; 7,487 biopsies) and angiographic intervention was needed in 0.6% of biopsies (95% CI 0.4 to 0.8; 24 studies, 8,445 biopsies). Other complication rates were low: urinary tract obstruction was seen in 0.3% of 2,416 biopsies; unilateral nephrectomy in 0.01% of 8,941 biopsies and two patients died out of 8,971 biopsies.
Results for predictors of macroscopic haematuria and erythrocyte transfusion were reported in the paper.