As mentioned earlier, PSA, anal examination and transrectal prostate ultrasound are now internationally recognized as the best methods for early detection of prostate cancer. Now that we all know the important role of PSA and anal exams, let’s take a look at why transrectal prostate ultrasound is necessary. Unlike a regular ultrasound through the abdominal wall, transrectal prostate ultrasound involves slowly inserting a thin ultrasound probe through the anus into the patient’s rectum and pressing its tip against the surface of the prostate for measurement. With this examination, a clearer ultrasound image of the prostate can be obtained with greater accuracy than with regular ultrasound. Perhaps readers may ask, what is the difference between transrectal prostate ultrasound and anal examination? Although the anal exam is simpler and cheaper, it is more demanding on the physician, and because the finger can only reach the back surface of the prostate, if the tumor is small or in a more forward position, it cannot be detected through the anal exam. This is where transrectal ultrasound can make up for this deficiency. In addition to these advantages, transrectal prostate ultrasound is also widely used to guide systematic puncture biopsies of the prostate. However, no test can be perfect. The specificity of transrectal prostate ultrasound is low, resulting in a certain number of “false” positives, or “false positives”. Because of this, an experienced urologist will make full use of (but never fetishize) these tests, taking into account the patient’s symptoms and other factors, to assess whether further, more complex, more expensive, but more accurate tests are needed. After all, every responsible physician will try to detect all “latent” prostate cancers, and would not want to miss even 1% of them.