Why Prostate Weight Matters for Surgery

When your urologist discusses surgical options for BPH, one of the first things they consider is your prostate's weight—not just its volume. While related, weight provides additional insight for surgical planning. Understanding why weight matters helps you participate in treatment decisions.

Convert your volume to weight using our Prostate Weight Calculator.

Volume vs. Weight: What's the Difference?

Prostate volume is measured in cubic centimeters (cc) or milliliters (mL). Prostate weight is measured in grams (g). The conversion uses tissue density:

This means a 50cc prostate weighs approximately 52.5 grams. The 5% difference comes from prostate tissue being slightly denser than water.

Why Surgeons Think in Weight

1. Procedure Duration Estimation

Surgical time correlates with tissue weight removed:

• TURP: ~1 gram/minute resection rate for experienced surgeons
• HoLEP: 1-2 grams/minute enucleation rate
• GreenLight: ~2-3 grams/minute vaporization

A 40-gram prostate might take 40-60 minutes of resection time; a 100-gram prostate might take 90-120 minutes.

2. Blood Loss Prediction

Expected blood loss scales with weight:

• Research shows ~15-20mL blood loss per gram resected in TURP
• Larger prostates = more blood loss = higher transfusion risk
• This influences anesthesia planning and blood typing

3. TUR Syndrome Risk

Traditional TURP uses irrigation fluid that can be absorbed. Longer procedures (larger prostates) increase risk of "TUR syndrome"—fluid overload causing electrolyte disturbances.

4. Procedure Selection

Many surgical thresholds are weight-based:

Weight Categories and Implications

Small Prostate (<30g)

• Most procedures technically straightforward
• May not benefit from 5-ARI medication (minimal shrinkage possible)
• Symptoms may be due to bladder rather than prostate

Medium Prostate (30-80g)

• Widest range of treatment options
• "Sweet spot" for minimally invasive procedures
• Standard TURP very effective

Large Prostate (80-150g)

• HoLEP becomes preferred procedure
• Standard TURP more challenging (prolonged OR time)
• Simple prostatectomy an option
• Blood loss concerns more significant

Very Large Prostate (>150g)

• Specialized centers recommended
• HoLEP at expert hands or robotic simple prostatectomy
• Blood product preparation typically required
• Extended hospital stay possible

Pre-Surgical Weight Reduction

Some surgeons recommend 5-alpha reductase inhibitors (finasteride/dutasteride) for months before surgery to:

• Shrink prostate 20-30% (reducing operative weight)
• Decrease vascularity (reducing blood loss)
• Shorten operative time

A 100g prostate might shrink to 70-80g with 6 months of medication, potentially changing surgical approach.

How Weight Is Measured

Pre-operatively (Estimated)

• Ultrasound or MRI volume × 1.05
• This is an estimate based on imaging

Post-operatively (Actual)

• Resected tissue is weighed in pathology
• This provides actual weight removed
• Often less than total pre-op estimate (not all tissue removed)

Questions for Your Surgeon

1. What is my estimated prostate weight?
2. How does my weight affect procedure selection?
3. What is the expected operative time?
4. What are the blood loss expectations?
5. Would pre-operative medication help?

Key Takeaways

Calculate your prostate weight with our free Weight Calculator.