The role of ultrasound-guided biopsy in allogeneic renal transplant

Abstract

Rejection has been one of the major causes of functional deterioration of renal allografts. Its nonspecific clinical manifestations sometimes make differential diagnosis from other clinical situations fairly difficult. Histological examination was previously necessary to make a definitive diagnosis and was helpful in preventing excessive or inadequate immunosuppression. We performed 105 ultrasound-guided biopsies of renal allografts in 70 patients from November 1996 to March 1999. Patients were divided into two groups according to the size of the Uro-Cut biopsy needle (16-gauge or 18-gauge). The complication rate (9.3% and 6.7%) (p = 0.659) and diagnostic rate (97.4% and 100%) (p = 0.366) showed no statistically significant differences between the two groups. Two patients in the group with 16-gauge needles required repeat biopsies due to insufficient renal tissue being available. The rate of successful biopsies (more than five intact glomeruli) was statistically higher in the group with 16-gauge needles (88%) than in the group with 18-gauge needles (53.3%) (p < 0.001). The average number of glomeruli was also statistically higher in the group with 16-gauge needles (15.2) than the group with 18-gauge needles (6.5) ( p < 0.001). The histological findings included 69 episodes of acute rejection, 27 episodes of chronic rejection or allograft nephropathy, 5 episodes of acute tubular necrosis, and 2 cases with infection. Corticosteroid pulse therapy and adjustment of immunosuppression were instituted for 69 episodes of acute rejection. However, excessive immunosuppression was avoided in another 34 episodes of deterioration of graft function which were proven to be other than acute rejection by graft biopsy. More than half of the biopsies of allografts were performed within 6 months after renal transplantation. We conclude that ultrasound-guided renal biopsy in allografts is a safe and effective procedure and should be considered for all patients with deterioration of graft function. It gives timely and adequate immunosuppression for patients with histology-proven acute rejection, and avoids excessive immunosuppression for patients proven otherwise. A 16-gauge Uro-Cut biopsy needle is a suitable device to obtain adequate tissue for histological diagnosis with an acceptable rate of complications.