Risk Factors For Infection Following Prostate Biopsy
A prostate biopsy is used to confirm or diagnose prostate cancer. During this procedure, doctors collect tissue samples to look at for signs of cancer. Your doctor may recommend a biopsy based on your results from a prostate-specific antigen (PSA) blood test.1
The most common type of prostate biopsy is the transrectal ultrasound (TRUS)-guided biopsy. TRUS biopsies are usually safe. However, rates of infections after TRUS biopsies are rising.2
Researchers are studying ways to reduce the risk for post-biopsy infection. This includes using other biopsy techniques with a lower risk of infection. It also includes avoiding unneeded biopsies.2
What is a TRUS biopsy procedure?
TRUS-guided biopsy is the most common way to collect tissue from the prostate. During the procedure, an ultrasound probe helps guide a biopsy needle through the wall of the rectum. The needle then collects 12 tissue samples from the prostate.1,3
Though it is common, TRUS is a flawed method of finding cancer. Ultrasound does not show the location of cancer within the prostate. It only guides the biopsy needle to the prostate. This means that TRUS biopsies can miss cancer altogether or find only areas of low-grade cancer. As a result, doctors may fail to treat serious cancers.4
On the other hand, because doctors know that TRUS may miss areas of high-grade cancer, they may overtreat people with low-grade cancer. This can mean unnecessary surgery or other harmful treatments.4
TRUS biopsies are usually safe, convenient, and cost-effective. But the procedure can have side effects. Side effects of a TRUS biopsy may include:1,2
- Acute urinary retention
- Blood in urine or semen
- Rectal bleeding
- Erectile dysfunction
What are risk factors for post-biopsy infection?
Infection rates following TRUS biopsies have been increasing. The risk of infection after TRUS biopsy used to be around 1 percent. But in recent years, the risk has risen to 2 to 4 percent. This may be due to growing resistance to antibiotics. This is when certain antibiotics no longer work to fight infection in a person.2,5
The growing risk of infection also may be due to higher rates of other chronic conditions, such as diabetes. Other factors that put people at greater risk for post-biopsy infection include:2,5
- History of urinary retention
- History of urinary infection
- Higher number of samples taken
How can we reduce the risk of post-biopsy infection?
Reducing unneeded biopsies is the best way to reduce the risk of infections. In not all but some cases, PSA screening may lead to biopsies on cancers that develop too slowly to cause problems. In these cases, TRUS biopsies can lead to unneeded side effects and overtreatment.6
In the opposite case, when the cancer has progressed to the point where surgical or radiation treatment is needed, a biopsy is not necessary.6
Preventive measures can help reduce the risk of post-biopsy infection. Some doctors prescribe oral antibiotic drugs a day before the TRUS biopsy. Fluoroquinolines are the most common antibiotics used for this purpose.2
But bacteria are becoming more resistant to fluoroquinolines. So experts are exploring other approaches to prevent post-biopsy infections. This includes using targeted therapies along with fluoroquinolines. It may also include cleaning the rectum with povidone-iodine.7,8
What are other prostate biopsy options?
Other prostate biopsy approaches may have a lower risk of infection. One approach is a transperineal (TP) biopsy. Here, the biopsy needle reaches the prostate through the skin between the anus and the scrotum. This reduces exposure to fecal bacteria.1
TP biopsies have a lower risk of infection. But they are more expensive and time-consuming than TRUS biopsies. They also usually require general anesthesia, while TRUS biopsies only need local anesthesia. This means you have to be put to sleep for a TP biopsy.2
Also, other biopsy approaches may lead to more accurate diagnoses. One approach combines magnetic resonance imaging (MRI) with ultrasound. MRI can help find areas of cancer in the prostate before the biopsy happens. Ultrasound is betting for real-time imaging to guide the biopsy. Combining the MRI and ultrasound images can help doctors guide the biopsy to areas of possible cancer.4
MRI targeting helps doctors find high-grade prostate cancers. It also helps doctors avoid areas of low-grade cancers that are unlikely to progress. MRI targeting seems to reduce the risk of infections. This is because MRI-targeted biopsies only need 3 to 5 tissue samples, instead of 12.9-11
Researchers are looking for better and safer ways to perform prostate biopsies. They are also studying how to better screen for prostate cancer. This can ensure that biopsies are only performed when necessary.4
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