Prostate Overview, Transrectal Ultrasound, and Prostate Biopsy
The prostate is a walnut-sized gland located beneath the bladder and in front of the rectum in men. The urethra (tube that transports urine and sperm out of the body) passes through the prostate to the bladder neck. Prostate tissue produces prostate specific antigen and prostatic acid phosphatase, an enzyme found in seminal fluid (the milky substance that combines with sperm to form semen).
Ultrasound, or ultrasonography, involves using a special device (transducer) that reflects high-frequency sound waves off internal structures to create detailed images called sonograms. Transrectal ultrasound (TRUS), also called prostate ultrasound, provides images of the prostate and surrounding tissue and allows the physician to examine the gland for abnormalities (e.g., enlarged prostate [BPH], prostate cancer).
TRUS and prostate biopsy can be used to diagnose prostate cancer in patients with an abnormal digital rectal examination or elevated PSA level, to assess prostate volume, to detect inflammation of the prostate (e.g., prostatitis), and to help determine the cause of infertility (e.g., blockages caused by prostatic cysts). Transrectal ultrasound also can be used to deliver and monitor prostate cancer treatments such brachytherapy and cryotherapy.
TRUS & Prostate Biopsy Procedure
Patients may be instructed to discontinue blood-thinning medications (e.g., aspirin, ibuprofen) for a week to 10 days prior to undergoing TRUS and prostate biopsy. An antibiotic (e.g., ciprofloxacin) may be prescribed prior to and for a couple of days following the procedure to help prevent infection. Before undergoing prostate ultrasound, patients may be instructed to drink a few glasses of water because a full bladder can improve visualization of the prostate gland. An enema may be administered to cleanse the bowel.
Transrectal ultrasound, which is performed with the patient lying on his side with his knees bent, involves using a small cylinder-shaped transducer, which is lubricated and inserted into the rectum, and a monitoring device. The transducer directs high-frequency sound waves into the body. As these sound waves are reflected back to the transducer, it records and transmits them to the monitoring device, which creates the images (sonograms).
In the presence of an abnormal PSA and/or if the results of TRUS are suspicious for prostate cancer, a prostate biopsy is performed. During biopsy, transrectal ultrasound is used to help the physician properly place the needle, which is projected through the tip of a probe inserted through the rectum to the prostate. The biopsy needle is used to extract a tissue sample from one or more areas of the prostate. The biopsy samples are sent to a pathologist (physician who identifies diseases by studying cells under a microscope) who analyzes the sample(s) for the presence of prostate cancer.
The grade (degree of aggressiveness) of prostate cancer is evaluated using a method called the Gleason score. The biopsy sample is examined under a microscope for cells or groups of cells that are markedly different from healthy prostate tissue. The greater the disparity between the healthy cells and those that are malignant, the more likely the tumor is aggressive and will spread (metastasize).
The pathologist examines two tissue samples taken from different areas of the prostate and assigns a score of 1 to 5 to each sample. Tissue with a higher degree of abnormality is assigned a higher score. The sum of the two scores indicates the Gleason score. Gleason scores of 2 to 4 indicate that the cells are well differentiated, meaning the tissue is slightly abnormal; 5 to 7 moderately differentiated; 8 to 10 poorly differentiated. Higher scores suggest aggressive tumors that likely require aggressive treatment.
Complications of Prostate Biopsy
Transrectal ultrasound usually is not associated with side effects or complications. Following prostate biopsy, patients may experience blood in the urine (hematuria), in the semen (hematospermia), or in the stool, and a dull ache in the perineum (area between the anus and the scrotum). These side effects are usually minor and diminish within 1–2 weeks. Men may be advised to refrain from sexual intercourse for 3–5 days. If the patient develops a large number of blood clots or cannot urinate, the physician should be contacted immediately.
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