In a digital rectal examination (DRE), the doctor checks the prostate by putting a gloved, lubricated finger into the rectum to feel the back of the prostate gland. This allows him to feel the size of the gland and check for hard lumps, which could indicate cancer.
A rectal exam is extremely important in the assessment of prostate cancer and benign prostatic hyperplasia, an enlargement of the prostate with age, said Dr Ng Kok Kit, a senior consultant and the director of andrology service at Changi General Hospital's urology department.
"This is because the prostate gland cannot be seen or felt from outside the human body," he said.
A rectal exam allows doctors to assess the size and nature of the prostate gland, and the presence of a nodule there would require further assessment for prostate cancer, said Dr Ng.
The procedure is more commonly done at the primary-care level. In a specialist setting, said Dr Gerald Tan, a urologist in private practice, DREs are now "not commonly performed... as most urologists would have a bedside ultrasound machine for imaging the prostate and assessing its actual size."
Today, specialists perform DREs only to assess how aggressively prostate cancer has spread, and if it involves the surrounding structures, he said. Indeed, said Dr Ng, specialists have access to ultrasound machines, as well as other investigation tools such uroflowmetry, to help further assess prostate problems that are complicated or do not respond well to medications.
They are also able to carry out a prostate biopsy to diagnose prostate cancer.
"Primary practitioners, however, can assess prostate problems with a physical examination and an initial blood investigation," Dr Ng said.
They can perform a rectal exam to estimate the size of the prostate and check for prostate nodules, and do a prostate-specific antigen (PSA) blood test to check for suspected prostate cancer, he said.