Why MRI comes first
For many years, men with a raised PSA went straight to a biopsy taken through the back passage, with 10 to 12 samples from different parts of the prostate. This missed some significant cancers and found many small ones that would never have caused harm. An MRI scan before biopsy has changed that.
NICE guidance (NG131) recommends a multiparametric MRI scan as the first investigation for men with suspected localised prostate cancer. Read the NICE guideline
What the MRI scan involves
The scan takes about 30 to 40 minutes. You lie on your back in the scanner, and a contrast dye is sometimes given through a small needle in your arm. There is no radiation. Let us know beforehand if you have a pacemaker or other metal implant, kidney problems, or if you are claustrophobic.
A specialist radiologist scores any area of concern on a scale of 1 to 5 (the PI-RADS or Likert score):
| Score | What it means | Usual next step |
|---|---|---|
| 1 to 2 | Significant cancer very unlikely | Biopsy often not needed; PSA follow up. The decision also considers PSA density and family history |
| 3 | Uncertain | Discussed individually; biopsy often advised, particularly if the PSA is high for the size of the prostate |
| 4 | Significant cancer likely | Targeted biopsy recommended |
| 5 | Significant cancer highly likely | Targeted biopsy recommended |
Transperineal targeted biopsy
In a transperineal biopsy the needles pass through the skin between the scrotum and the back passage (the perineum), rather than through the wall of the back passage. This greatly reduces the risk of infection. The MRI images are used alongside live ultrasound so that samples are taken from the area of concern, together with samples from the rest of the prostate.
Before the biopsy
Tell us if you take blood thinning medication; we will give you a clear plan. Do not stop any medicine without advice.
Anaesthetic
Most biopsies are done under local anaesthetic, sometimes with light sedation. A general anaesthetic can be used if preferred or if more samples are needed.
Taking the samples
An ultrasound probe in the back passage provides the images. The needle passes through the numbed skin of the perineum to the target area. The procedure usually takes 20 to 40 minutes.
Going home
You go home the same day once you have passed urine. Arrange to be collected, particularly after sedation or a general anaesthetic.
Results
The samples are examined by a specialist pathologist. Results usually take 7 to 10 days and Mr Ameen will go through them with you in person.
Risks and side effects
Very common
Blood in the urine or semen
Blood in the urine usually settles within a few days. Blood in the semen can last several weeks and is harmless.
Common
Bruising and discomfort
Some tenderness and bruising of the perineum for a few days, eased by simple painkillers.
Uncommon
Difficulty passing urine
Swelling can occasionally make it hard to pass urine. A temporary catheter for a few days resolves this.
Rare with this approach
Infection
Below 1 in 100 after a transperineal biopsy. Seek urgent advice if you develop a fever or shivers.
For a full, independently written account read the BAUS transperineal biopsy patient leaflet.
Understanding your results
If cancer is found, the report gives a Gleason score (also expressed as a Grade Group from 1 to 5), which describes how aggressive the cells look, and how much of each sample is involved. Together with the PSA and MRI, this places the cancer in a risk group and guides the options, from active surveillance to robotic prostatectomy. Our prostate cancer guide explains each step.
If no cancer is found, you will usually continue with PSA checks, and the MRI provides a useful baseline if the PSA changes in future. Many men with a raised PSA turn out to have an enlarged prostate, and our enlarged prostate guide covers the options for urinary symptoms.
Frequently asked questions
Not always. If the MRI is reassuring and your PSA density and other risk factors are low, many men can safely avoid a biopsy and continue with PSA monitoring. Mr Ameen will advise you based on your full picture.
Under local anaesthetic most men feel pressure rather than pain, and the discomfort afterwards is usually mild. A general anaesthetic is available if you would prefer to be asleep.
The needles do not pass through the wall of the back passage, where bacteria live. This makes serious infection much less likely, and it also allows better sampling of the front of the prostate.
Do not stop any medication on your own. Tell us what you take and why, and you will be given a specific plan for the days around the biopsy.
A private MRI can usually be arranged soon after your consultation, with the biopsy, if needed, following shortly after the scan has been reported.