How is an Examination (Digital Rectal Exam/DRE) performed:
The digital rectal exam is the simplest way to detect physical abnormalities in the prostate gland that may suggest the presence of cancer. The DRE is also used to estimate the volume of the prostate and can sometimes help determine the extent of the cancer.
Unlike the standard approach taken by most urologists, where the patient is asked to bend over a table for the digital exam, we perform digital examinations of the prostate with the patient in the dorsal lithotomy position – lying on his back with his legs drawn up (much like the position a woman is in for a pap smear – see illustration). This position causes the prostate gland to literally fall naturally against the physician’s fingers, allowing for a more complete and relaxed examination of the gland.
To perform the rectal exam, the doctor feels the gland by placing a lubricated, gloved finger inside the rectum against the prostate. When done properly, the test is not as discomforting as it might sound. Most cancers are located in the back of the prostate, and some of these cancers that have grown at the edge of the gland can be felt as a lump or hard nodule. Depending on the size, shape and location of the lump, it is sometimes possible to determine with a DRE if the cancer is likely to have spread beyond the prostate capsule. With the DRE, the doctor is able to evaluate the major portions of the gland’s anatomy: the right and left sides or lobes; the upper portion of the base of the gland the middle portions of the gland’s anatomy; the right and left sides or lobes; the middle portion of the gland; and lower portion or apex. However, not all surfaces of the gland can be reached by the DRE.
Unfortunately, the DRE is often not accurate. Many prostate cancers do not protrude against the back of the gland; they are not palpable and cannot be detected with the DRE. A tumor at the front of the prostate cannot be felt through the rectum. In addition, the test is subjective and depends on the skill of the doctor, providing at best only an estimate of the extent of the disease. Many surgical studies have shown that more than 50% of cancers that appear to be confined to the gland will later be found to have spread beyond the gland. However, DRE is important as it is sometimes able to reveal tumors that would have been missed by PSA blood test alone.