A transrectal ultrasound (TRUS) is an imaging technique that uses high-frequency sound waves to create real-time pictures of organs and tissues near the rectum, primarily the prostate gland in men. The procedure involves inserting a small probe into the rectum, which often causes anxiety about potential pain. While any internal procedure can be unsettling, the experience is typically described as involving pressure rather than sharp pain. Understanding the procedure and pain management steps can help alleviate worry.
Why This Test Is Necessary
Physicians order a transrectal ultrasound to obtain a detailed view of the prostate gland and surrounding structures. The rectum’s close proximity to the prostate allows the TRUS probe to generate superior image resolution compared to external ultrasound methods. This detailed visualization is often needed when blood work shows an elevated prostate-specific antigen (PSA) level, or if a digital rectal exam (DRE) reveals an abnormal area.
TRUS is frequently used to assess the size and shape of the prostate, relevant for diagnosing conditions like benign prostatic hyperplasia (BPH). Physicians also use TRUS to look for suspicious areas suggesting prostatitis or prostate cancer. The scan also provides information about the seminal vesicles.
The most common application of TRUS is providing real-time guidance during a prostate biopsy. The live imaging allows the doctor to precisely target suspicious areas within the gland to collect tissue samples for laboratory analysis. This precision increases the accuracy of cancer detection. TRUS may also be used to guide certain prostate cancer treatments or to assess the extent of cancer spread.
Preparation, Procedure, and Pain Management
Preparation involves steps to ensure the rectum is clear, which improves image quality and reduces infection risk, especially if a biopsy is planned. Patients are often instructed to use a cleansing enema one to four hours before the procedure. They may also be asked to stop taking blood-thinning medications, such as aspirin, several days beforehand to minimize bleeding risk.
The procedure is typically brief, lasting 10 to 30 minutes, with the patient lying on their side with their knees pulled toward their chest. The provider first performs a digital rectal exam before inserting the probe. The ultrasound probe, approximately the width of a finger, is covered with a protective sheath and coated in lubricating gel.
The probe is gently inserted into the rectum and rotated to capture images of the prostate from various angles. During insertion, the sensation is usually described as an uncomfortable feeling of pressure or fullness in the rectum, similar to the urge to have a bowel movement. The rectal mucosa is not sensitive to pain, but the probe’s expansion causes the sensation of pressure.
If a prostate biopsy is performed concurrently, additional pain management measures are taken because the prostate capsule is sensitive. The standard method is a periprostatic neurovascular bundle block (PNB), which involves injecting a local anesthetic, such as lidocaine, near the nerves surrounding the prostate. This numbing agent reduces the discomfort associated with the biopsy needle passing into the gland. The combination of a quick procedure, lubrication, and local anesthetic means the TRUS is well-tolerated.
Immediate Aftercare and Recovery
Following a TRUS without a biopsy, patients can typically resume normal activities immediately. If a biopsy was performed, the recovery involves managing expected side effects. Patients are often prescribed antibiotics to take before and after the procedure to reduce infection risk.
Mild discomfort or soreness in the rectal area is common for several days following a TRUS-guided biopsy. Patients may notice small amounts of blood in their urine or stool for a few days, which is temporary. A more noticeable side effect is blood in the semen, known as hematospermia, which can cause the semen to appear rust-colored for several weeks, sometimes persisting for up to 12 weeks.
Patients are advised to increase fluid intake for the first few days to help flush the bladder and reduce blood clot formation. While these side effects are normal, it is important to contact a healthcare provider immediately if warning signs appear. These include:
- Fever greater than 100.5°F.
- Heavy bleeding that will not stop.
- Passing of large stringy blood clots.
- Sudden inability to urinate.