Urine cytology: an underused method to diagnose acute renal allograft rejection.

In children, the early detection and accurate diagnosis of acute renal allograft rejection (AR) may be difficult. A delay in the diagnosis and treatment of AR might engender a poor outcome. Core needle biopsy is diagnostic but invasive. However, only a few less-invasive means to diagnose AR are sufficiently accurate to warrant their routine use. One such method is urine cytology. Investigators have demonstrated in more than 800 patients that urine cytology is simple and reliable for diagnosing graft failure. These observations may be important for children, for whom a non-invasive, accurate, and easily repeated indicator of AR may be particularly useful. While not a substitute for transplant biopsy, urine cytology may reduce diagnostic uncertainty and indicate the need for core needle sampling in a timely manner.