Transrectal ultrasound (TRUS) guided prostate biopsy

Transrectal ultrasound (TRUS) can be used to examine the prostate and assess the size of the gland accurately. But the main function of TRUS is to enable precise needle placement in the prostate during systematic prostate biopsy (1).

To help men decide whether to have a prostate biopsy, healthcare professionals should discuss with them their PSA level, digital rectal examination findings (including an estimate of prostate size) and comorbidities, together with their risk factors (including increasing age and black African or black Caribbean ethnicity) and any history of a previous negative prostate biopsy (2)

The information from the multiparametric MRI (mpMRI) scan taken before prostate biopsy is used to determine the best needle placement. In rare cases, the biopsy may be MRI-guided (the needle is inserted within the MRI machine). In most cases, the biopsy that follows the mpMRI will be ultrasound-guided, but the specific area(s) targeted will be predetermined by the mpMRI data (2)

• it is important to remember that serum PSA level alone should not automatically lead to a prostate biopsy 10 to 12 cores of prostatic tissue are taken through the rectum under ultrasound guidance (1)
• aim of prostate biopsy is to detect prostate cancers with the potential for causing harm rather than detecting each and every cancer
• men with clinically insignificant prostate cancers that are unlikely to cause symptoms or affect life expectancy may not benefit from knowing that they have the disease. Indeed, the detection of clinically insignificant prostate cancer should be regarded as an under-recognised adverse effect of biopsy (1)

A prostate biopsy for histological confirmation should not be performed in cases where clinical suspicion of prostate cancer is high, because of a high PSA value and evidence of bone metastases (identified by a positive isotope bone scan or sclerotic metastases on plain radiographs), unless this is required as part of a clinical trial (2).

Previous negative prostate biopsy results are associated with a reduced risk of finding a high-grade cancer (1).

A core member of the urological cancer MDT should review the risk factors of all men who have had a negative first prostate biopsy, and discuss with the man that (1):

• there is still a risk that prostate cancer is present and
• the risk is slightly higher if any of the following risk factors are present:
  • the biopsy showed high-grade prostatic intra-epithelial neoplasia (HGPIN)
  • the biopsy showed atypical small acinar proliferation (ASAP)
  • abnormal digital rectal examination

Magnetic resonance imaging for rebiopsy (2)

• consider multiparametric MRI (using T2- and diffusion-weighted imaging) for men with a negative transrectal ultrasound 10-12 core biopsy to determine whether another biopsy is needed

Reference:

• 1. Prostate Cancer Risk Management Programme Information for primary care; PSA testing in asymptomatic men. Evidence document. NHS Cancer Screening Programmes, 2010
• 2. National Institute for Health and Clinical Excellence (NICE) 2019. Prostate cancer: diagnosis and treatment.