Prostate Cancer Diagnostic tests – the digital rectal examination - TRUS

Regular screening for prostate cancer can help to save your life; it is as simple as that. It is recommended to begin testing for prostate cancer from the age of forty. There are two main types of diagnostic tests: those that use the digital rectal exam and those that use prostate specific antibodies. Many procedure such as TRUS may be carried out as follow ups to the initial physical rectal examinations.

Digital Rectal Exam

As the prostate is located next to he rectum and very close to the anal opening it is easy for a doctor to access it through the anal opening. The procedure itself typically takes about a minute and can be performed either with the patient lying on his side or standing up (bent forward).

The prostate normally has a smooth elastic surface, if the doctor feels that it is rough then it is a sign that the prostate may be abnormal, enlargement of the prostate is also detectable by this method. Cancers normally show themselves on the peripheral zone and often begin as hard nodules; these are usually small in size at the beginning. Only about half of the lumps that are detected by performing a digital rectal exam are cancerous, many turn out to be stones, inflammations or other benign prostate hyperplasia conditions. However, if a lump is found it is always necessary to carry out more advanced tests to ensure that the patient does not have prostate cancer.

One of the drawbacks of the digital rectal exam is that it can underestimate tumour volumes. It is also possible that the examination may prove negative in the detection of the cancer condition due to masking by benign prostate hyperplasia conditions. If a hard lesion is found when performing a digital rectal examination the doctor will normally recommend that the patient visit a urologist; a needle biopsy or transrectal ultrasound will then be performed to investigate the condition of the prostate further.

Because of the difficulties in determining if the prostate is cancerous by performing a rectal exam it is recommended that a prostate specific antigen test is carried out concurrently.

Transrectal ultrasound -TRUS

This technique, also known as TRUS (Trans Rectal Ultra Sound) measures the size of the prostate by sound. As suggested by the word transrectal which means ‘through the rectum’. The probe is inserted into the rectum, where it emits harmless ultrasound waves; this enables the prostate surface to be mapped and any enlargement, lesions or other prostate abnormalities can be easily detected. Often the doctor will take a biopsy at the same time as performing TRUS; this is performed by inserting a needle through the probe and scraping cells from several areas of the prostate. Usually six samples are taken; this gives the procedure its sextant biopsy name. Although the procedure itself is simple, usually taking place in a urologists office or as an outpatient, the patient’s preparation is not. The patient must take antibiotics to prevent bacterial infections and take an enema 3 hours before the treatment to flush out the rectum. The procedure takes about twenty minutes to perform, the patient usually lies on his side and brings his knees to his chest; the probe is then inserted. An advantage of transrectal ultrasound is that it can often identify cancer that cannot be felt by the digital rectum exam. The use of TRUS without biopsy is not faultless; certain diffuse cancers are difficult to visualise.