CORRELATION BETWEEN CYSTOSCOPIC BIOPSY RESULTS AND HYPOAMYLASURIA IN BLADDER-DRAINED PANCREAS TRANSPLANTS

Background. Urinary amylase (UA) remains the most common biochemical p arameter to detect rejection in bladder drained pancreas allografts. W ith the development of the cystoscopic transduodenal pancreas transpla nt biopsy technique, tissue samples of the pancreas graft are now freq uently obtained. A definitive correlative analysis between UA activity and biopsy results has not been done in the three different pancreas transplant categories (simultaneous pancreas-kidney, pancreas transpla nt alone, and pancreas after kidney). Methods. We studied 66 pancreati coduodenal biopsy specimens obtained for hypoamylasuria. Rejection was defined as a greater than 25% decrease from stable posttransplantatio n baseline on two consecutive measurements at least 12 hours apart. To perform biopsies we used our newly developed 14- and 16-gauge core-cu t needles (50 cm long). Biopsy specimens were considered positive if e ither pancreatic or duodenal rejection was found. To assess the qualit y of UA activity we studied 13 biopsy specimens from patients with sta ble UA levels; these 13 specimens were negative for rejection. Results . Acute rejection was diagnosed in 36 biopsy specimens (55%). The mean decease in UA levels was 67% +/- 8% (range, 28% to 99%) for the posit ive biopsy results, and 57% +/- 16% (range, 22% to 92%) for the negati ve biopsy results (p = 0.147). Within 1 month, UA levels returned to b aseline in 19% of our patients with positive biopsy results versus 97% with negative results, postbiopsy 1-year graft survival was 64 % vers us 97% (p less than or equal to 0.05). ln assessing the test quality o f our biopsy specimens (including 13 obtained for reasons other than h ypoamylasuria), we found a sensitivity of 100% (stable UA levels mean no rejection) and a specificity of 30%. The predictive value of a posi tive test tons 53%; of a negative test it was 100%. By performing biop sies we avoided antirejection treatment in 47% of the patients studied . We found no biopsy-related complications. Conclusions. Stable UA lev els reliably rule out rejection; a decrease is a marker for acute reje ction but is unspecific. Performing biopsy is currently the only way t o reliably diagnose rejection in solitar pancreas recipients (pancreas transplant alone and pancreas after kidney) and in simultaneous pancr eas-kidney recipients with isolated hypoamylasuria. The procedure is s afe and should always be attempted to avoid unnecessary rejection trea tment.