Transrectal vs. Transperineal Biopsy: Which Is Safer?

What is the difference between the two approaches?

Both approaches do the same job: they take small samples of prostate tissue with a thin needle, usually guided by ultrasound and MRI, so a pathologist can check for cancer.

The difference is the route the needle takes to get there.

In a transrectal biopsy, the needle passes through the wall of the rectum and into the prostate. In a transperineal biopsy, the needle passes through the perineum — the skin between the scrotum and the rectum — and into the prostate.

That's the whole difference: same needle, same goal, different path. And as you'll see, the path matters a lot. This is called a transperineal biopsy.

Which one is safer?

When it comes to infection, transperineal offers the cleaner path.

The rectum is full of bacteria. When the biopsy needle passes through the rectal wall, it can carry those bacteria into the prostate and the bloodstream. That's why men having a transrectal biopsy need antibiotics beforehand — and why infection, including a serious bloodstream infection called sepsis, is the most concerning complication. Roughly 1 to 2 in 100 men develop sepsis after a transrectal biopsy, and that number has been creeping up as bacteria become more resistant to antibiotics.

A transperineal biopsy avoids the rectum entirely. The needle passes through clean skin instead, so there's much less chance of introducing bowel bacteria into the body. The reported risk of sepsis is about 1 in 500.

To be fair, no approach is perfect: transperineal biopsies may carry a slightly higher chance of temporary difficulty urinating afterward, though studies have shown mixed results on this point. And transrectal biopsy remains a reasonable option that many urologists perform well. But if minimizing infection risk is the priority, the transperineal route is the cleaner one. That's why I use it for my patients.

Is transperineal just as accurate?

Yes — and it may even find slightly more.

Accuracy comes down to whether the needle reaches the suspicious area, and both approaches can be guided by MRI. The transperineal route actually reaches some areas better — particularly the front of the prostate and the apex (the tip), which are harder to sample through the rectum.

In the largest randomized trial comparing the two, transperineal biopsy found clinically significant cancer slightly more often — 60% versus 54%. That difference wasn't large enough to be definitive, but it confirms transperineal gives up nothing on accuracy.

So you get the cleaner path without trading away detection.

Which one would you recommend?

For my patients, transperineal.

One reason some men end up with a transrectal biopsy is the belief that transperineal requires general anesthesia. It doesn't. I perform transperineal biopsies with local anesthesia — a lidocaine injection around the prostate — and for about 80% of my patients, I add conscious sedation: IV medication that leaves you very groggy but breathing on your own. Most men remember little or nothing afterward.

So the choice isn't between comfort and safety. You can have a comfortable biopsy through the cleaner path.

If your urologist only offers transrectal biopsy, it's worth asking whether transperineal is an option — or getting a second opinion from someone who performs it.

By Chad Ellimoottil, MD — urologist at Michigan Medicine specializing in prostate cancer detection.

Disclaimer: This information is for general educational purposes only and is not medical advice. Please consult a qualified healthcare professional about any medical condition, diagnosis, or treatment decision.