According to the American Urological Association, surgical intervention is recommended for prostates that have a volume of 30 cc or larger with notable lower urinary symptoms. However, an enlarged prostate becomes dangerous when it prevents the proper flow of urine, potentially causing backflow that leads to bladder and kidney infections. In some cases, an enlarged prostate can block urine flow completely or result in kidney failure. There is no way to predict how quickly the growth of the prostate may affect the urinary tract. In some people, minor enlargement may cause serious symptoms, while other people may have lemon-sized prostates with minimal complications. Therefore, the size of the prostate alone is not the only factor used to determine whether it is dangerous or not. The severity of symptoms and the effect on urinary flow are also important factors to consider.