Prostate Biopsy: MRI-Fusion & Transrectal Biopsy – Complete Guide

What is a prostate biopsy?

A prostate biopsy is a procedure that removes small samples (cores) of prostate tissue to be examined under a microscope for cancer cells. It is the only definitive way to diagnose prostate cancer.

The biopsy is typically performed using ultrasound guidance, with needles inserted through the rectum (transrectal) or through the perineum (transperineal). MRI-fusion biopsy combines MRI images with real-time ultrasound to target suspicious lesions.

When is a prostate biopsy needed?

Indications for prostate biopsy include:

• Elevated PSA: >4 ng/mL (or age-specific threshold) with concerning features (PSA density >0.15, velocity >0.75)
• Abnormal DRE: Hard nodule or asymmetry (regardless of PSA level)
• Suspicious MRI: PI-RADS 4-5 (or PI-RADS 3 with other risk factors)
• Active surveillance: Repeat biopsy to monitor for progression
• After negative biopsy with persistently elevated PSA

Types of prostate biopsy

Three main approaches are used, each with advantages and disadvantages:

• Transrectal ultrasound (TRUS) biopsy: Needle passes through the rectal wall into the prostate. Most common, done in office.
• MRI-fusion biopsy: MRI images fused with real-time ultrasound to target suspicious lesions. More accurate for significant cancer.
• Transperineal biopsy: Needle passes through the perineal skin (between scrotum and anus). Lower infection risk, but requires general anaesthesia.

MRI-fusion biopsy – how it works

MRI-fusion biopsy (also called MRI-targeted or cognitive fusion biopsy) is the current gold standard for men with a suspicious MRI.

How it works:

• Step 1: Multiparametric MRI (mpMRI) identifies suspicious lesions (PI-RADS 3-5)
• Step 2: During biopsy, the MRI images are fused (overlaid) with real-time ultrasound
• Step 3: The urologist targets the suspicious lesion(s) with 2-4 cores
• Step 4: Systematic biopsy (12 cores) is often still performed concurrently

Advantages:

• Detects 30-40% more clinically significant cancers than systematic biopsy alone
• Reduces detection of low-risk (insignificant) cancers
• Fewer cores needed

Transrectal ultrasound (TRUS) biopsy

TRUS biopsy is the traditional standard. It is performed in the office under local anaesthesia.

Procedure:

• An ultrasound probe is inserted into the rectum
• The prostate is visualised on the ultrasound screen
• A spring-loaded biopsy needle passes through the rectal wall into the prostate
• Typically 12 cores are taken (systematic sampling of both lobes)
• The entire procedure takes 10-15 minutes

Limitations:

• Infection risk (1-5%) – bacteria from rectum
• May miss anterior or apical cancers not well visualised on ultrasound
• Detects many low-risk (insignificant) cancers

Transperineal biopsy – lower infection risk

Transperineal biopsy passes the needle through the perineal skin (between scrotum and anus) instead of through the rectum.

Advantages:

• Much lower infection risk: <1% (vs. 1-5% for transrectal)
• Can sample the anterior prostate better
• No need to stop blood thinners (lower bleeding risk)

Disadvantages:

• Requires general or spinal anaesthesia (not office-based)
• More time-consuming
• May cause more post-procedure discomfort

Preparation – antibiotics, blood thinners, enema

Proper preparation reduces complication risk:

Antibiotics (for transrectal biopsy):

• Prophylactic antibiotics are given before transrectal biopsy
• Typically fluoroquinolone (ciprofloxacin) or cephalosporin
• May require rectal swab to screen for antibiotic-resistant bacteria

Blood thinners:

• Stop aspirin, clopidogrel, warfarin, apixaban, rivaroxaban as directed (typically 5-7 days before)
• Transperineal biopsy may allow continuation of blood thinners

Enema:

• A Fleet enema is typically used 1-2 hours before transrectal biopsy to clear the rectum
• Reduces bacterial load and infection risk

The biopsy procedure – step by step

During the procedure (TRUS or MRI-fusion):

1. You lie on your side with knees drawn to chest
2. Local anaesthetic gel is applied to the rectum
3. An ultrasound probe is inserted (or MRI-fusion device)
4. The prostate is visualised
5. Local anaesthetic (lidocaine) is injected into the prostate (nerve block)
6. A spring-loaded biopsy needle takes 12-15 cores (2-4 targeted + 12 systematic)
7. Each core takes about 1 second – you may hear a "click"
8. The probe is removed – no stitches needed

Pain management:

• Periprostatic nerve block (lidocaine injection) is highly effective
• Most men feel pressure, not sharp pain
• Procedure takes 10-20 minutes

Risks and complications – infection, bleeding, retention

Prostate biopsy is safe but has risks:

Common (1-10%):

• Blood in urine (hematuria): 50-80% – resolves in 3-7 days
• Blood in semen (haematospermia): 30-50% – may last 4-6 weeks (normal)
• Blood in stool (rectal bleeding): 10-20% – resolves in 1-3 days

Less common (1-5%):

• Urinary tract infection (UTI): 2-5% – treat with antibiotics
• Acute prostatitis: 1-2% – fever, pelvic pain, requires antibiotics
• Sepsis (serious infection): 0.5-1% – requires hospitalisation
• Urinary retention: 1-2% – inability to urinate, requires temporary catheter

Rare (<1%):

• Rectal bleeding requiring transfusion
• Epididymitis

Recovery and results

Recovery timeline:

• Day 1-3: Blood in urine, mild pelvic discomfort, rectal bleeding
• Week 1: Most bleeding resolves; avoid heavy lifting, strenuous exercise
• Week 2-4: Blood in semen may persist (normal)
• Week 6-8: Semen returns to normal colour

Results timeline:

• Pathology results typically available in 5-10 days
• Your urologist will discuss the results and next steps

Possible results:

• Negative (no cancer): Discuss follow-up (repeat PSA, MRI, or repeat biopsy)
• Low-risk cancer (Gleason 6): Active surveillance may be appropriate
• Intermediate/high-risk cancer (Gleason 7+): Treatment discussion (surgery, radiation)

Interactive FAQ – Prostate biopsy

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Disclaimer: This information is for educational purposes. Prostate biopsy is a medical procedure with risks. Discuss with a urologist at Vivekananda Hospital to determine if a biopsy is right for you.