Safety and adequacy of renal transplant protocol biopsies.

The protocol biopsy strategy has been criticized because of risks and marginal utility. We tested the risk. We performed 1171 protocol biopsies in 508 patients at 6, 12 and 26 weeks after renal transplantation, as well as 499 biopsies as indicated in 429 transplant patients. Biopsies were done as an outpatient procedure using an 18- or 16-gauge automated biopsy needle followed by 4 h bed rest. Complications were: gross hematuria 3.5%, perirenal hematomas 2.5%, arterio-venous fistulas 7.3% and vasovagal reactions 0.5%. Major complications requiring invasive procedures such as blood transfusions or urinary catheter were seen in 1% of cases. The hospitalization rate for observation was 1.9%. According to the Banff criteria of specimen adequacy, biopsies with 18-gauge needles yielded >7 glomeruli and at least one artery in 53% of cases. Changing the needle size in October 2003, those biopsies done with 16-gauge needles yielded >7 glomeruli and at least one artery in 76% of cases, while the rate of major complications did not change. In conclusion, transplant protocol biopsies with 16-gauge needles provide better utility and similar risk as biopsies with 18-gauge needles. A 4-h recovery after biopsy appears adequate for discharge.

The renal arterial resistance index and renal allograft survival.

BACKGROUND: Most renal transplants fail because of chronic allograft nephropathy or because the recipient dies, but no reliable factor predicting long-term outcome has been identified. We tested whether a renal arterial resistance index of less than 80 was predictive of long-term allograft survival. METHODS: The renal segmental arterial resistance index (the percentage reduction of the end-diastolic flow as compared with the systolic flow) was measured by Doppler ultrasonography in 601 patients at least three months after transplantation between August 1997 and November 1998. All patients were followed for three or more years. The combined end point was a decrease of 50 percent or more in the creatinine clearance rate, allograft failure (indicated by the need for dialysis), or death. RESULTS: A total of 122 patients (20 percent) had a resistance index of 80 or higher. Eighty-four of these patients (69 percent) had a decrease of 50 percent or more in creatinine clearance, as compared with 56 of the 479 patients with a resistance index of less than 80 (12 percent); 57 patients with a higher resistance index (47 percent) required dialysis, as compared with 43 patients with a lower resistance index (9 percent); and 36 patients with a higher resistance index (30 percent) died, as compared with 33 patients with a lower resistance index (7 percent) (P<0.001 for all comparisons). A total of 107 patients with a higher resistance index (88 percent) reached the combined end point, as compared with 83 of those with a lower resistance index (17 percent, P<0.001). The multivariate relative risk of graft loss among patients with a higher resistance index was 9.1 (95 percent confidence interval, 6.6 to 12.7). Proteinuria (protein excretion, 1 g per day or more), symptomatic cytomegalovirus infection, and a creatinine clearance rate of less than 30 ml per minute per 1.73 m2 of body-surface area after transplantation also increased the risk. CONCLUSIONS: A renal arterial resistance index of 80 or higher measured at least three months after transplantation is associated with poor subsequent allograft performance and death.