ABSTRACT
In the past 20 years, numerous attempts have been made to develop noninvasive procedures for monitoring rejection episodes in solid organ transplantation. Although new activation markers detected from blood and urine specimens have shown accuracy and reliability (1,2), these tests are still research tools and have not been utilized in routine clinical practice. A needle biopsy is still the only reliable method to assess intragraft events and is considered the ‘‘gold standard’’ in clinical practice. However, in spite of increasingly accurate ultrasonographic techniques and safer needles, biopsies are still associated with a risk of bleeding, fistula formation (either arteriovenous or parenchymal), and infection.
