What Is a Prostate Biopsy?

Aug 22

4 min read

Updated: Aug 28

A prostate biopsy is a ten to twenty minute procedure that samples small pieces of prostate tissue, and most men describe it as uncomfortable rather than painful. It's the only test that can actually diagnose prostate cancer.

I'm a board-certified urologist, and I've performed many of these over the last decade. Here's what to expect.

Why do I need a biopsy if I already had an MRI?

Everything before this point, your PSA, your biomarkers, your MRI, estimates probability. None of it can confirm whether cancer is present.

A biopsy looks at real tissue under a microscope. As I tell patients: the MRI is the map, and the biopsy is the answer.

It also answers a second question that matters just as much. Not only whether cancer is there, but what kind. Aggressive, or slow enough that you may never need treatment at all.

What actually happens during a prostate biopsy?

An ultrasound probe goes into the rectum so I can see the gland. A thin needle then takes small tissue samples, which we call cores.

A standard systematic biopsy takes around twelve, following a mapped pattern across the prostate. If your MRI flagged a suspicious area, we take additional targeted cores from that specific spot.

Do I need an MRI first? For most men who've never had a biopsy, yes. This is a genuine change from a decade ago. An MRI tells us whether there's a region worth aiming at, and it meaningfully improves our odds of finding the cancers that matter.

When we overlay those MRI images onto live ultrasound during the procedure, that's an MRI fusion, or targeted, biopsy. In most cases we do both targeted and systematic cores, because cancer occasionally hides where the MRI didn't see it.

Transrectal or transperineal: what's the difference?

	How it's done	Key point
Transrectal	Lying on your side; needle passes through the rectal wall	Long-standing standard approach
Transperineal	Legs in stirrups; needle goes through skin between scrotum and anus	Avoids the bowel, which can reduce serious infection risk

Transperineal is increasingly the approach being used. Ask your urologist which one they perform.

Will I be awake?

About 80% of biopsies performed across the country are performed awake with local anesthetic. Some centers, like ours, offer conscious sedation. And some offer general anesthesia. Conscious sedation is a great balance between comfort and safety and has become the default option for the majority of biopsies are our center.

You'll feel pressure, and you'll feel the needle fire. It makes a sharp click that surprises people. Being fully under usually isn't necessary for a procedure this short, but it's worth discussing with whoever is performing yours.

What's normal afterward, and what isn't?

Expected, not complications:

Blood in your urine for a few days
Blood in your semen, sometimes for weeks or a couple of months
Soreness, and light rectal spotting after a transrectal biopsy

Call your doctor or go to the ER: fevers, chills, or difficulty urinating. Infection is uncommon but can be serious.

Most men return to normal activity within a few days. I'd skip heavy lifting, intercourse, and hard exercise for about a week.

The bottom line

Results take roughly a week. They'll show benign, or a Gleason score and Grade Group from 1 to 5 describing how aggressive the cancer looks.

Two things worth knowing. A biopsy can miss cancer, which is why we use MRI to aim and why a rising PSA after a negative biopsy sometimes means repeating it. And a biopsy does not cause cancer to spread. That myth has been studied and it does not happen.