After vasectomy, what laboratory tests and semen analysis schedule are recommended to confirm sterility?

Post-Vasectomy Laboratory Testing

A single post-vasectomy semen analysis (PVSA) showing azoospermia or rare non-motile sperm (≤100,000 non-motile sperm/mL) is sufficient to confirm sterility and allow discontinuation of alternative contraception. 1

Timing of Semen Analysis

• Perform PVSA at 8-16 weeks post-vasectomy to allow adequate clearance of residual sperm from the reproductive tract. 2
• The specimen should be collected after a minimum of 12 weeks and at least 20 ejaculations according to UK guidelines, though the AUA does not specify a minimum number of ejaculations. 3
• Number of ejaculations alone is NOT a reliable indicator of when sterility is achieved; time-based testing is more evidence-based. 2

Specimen Collection and Handling

• Examine a fresh, uncentrifuged, well-mixed semen sample within 2 hours of ejaculation to properly assess sperm motility. 1
• If non-motile sperm are observed on initial analysis, the specimen must be examined within 1 hour of production for accurate motility assessment. 3
• Do not centrifuge the specimen for routine PVSA, as centrifugation interferes with sperm motility assessment and may identify clinically insignificant numbers of sperm, leading to unnecessary repeat procedures. 1

Criteria for Clearance

Single specimen clearance is acceptable when:

• Complete azoospermia (no sperm visualized), OR
• Rare non-motile sperm (RNMS) defined as <100,000 non-motile sperm/mL 1, 3

The pregnancy risk after achieving either endpoint is approximately 1 in 2,000, which is considered acceptably low. 1

Management of Persistent Sperm

If non-motile sperm are present on first analysis:

• Perform repeat analysis in the surgeon's office to determine if azoospermia develops over time 2
• If persistent non-motile sperm remain, send specimen to a certified clinical laboratory for quantitative analysis 2
• If ≤100,000 non-motile sperm/mL, the patient may rely on vasectomy for contraception ("special clearance") 2, 3

If >100,000 non-motile sperm/mL or ANY motile sperm are present:

• Consider repeat vasectomy 2
• Use trends of serial analyses and clinical judgment to determine if vasectomy has failed 2
• If motile sperm persist at 6 months post-vasectomy, repeat vasectomy should be strongly considered 2

Critical Patient Instructions

• Continue using alternative contraception until sterility is confirmed by PVSA showing acceptable results. 1
• Patients should abstain from ejaculation for approximately one week immediately after the procedure to allow initial healing. 1, 2
• Assigning a specific follow-up appointment significantly improves compliance with post-vasectomy semen analysis compared to open-ended instructions. 2

Common Pitfalls to Avoid

• Do not rely on histologic examination of excised vas segments to confirm vasectomy success; PVSA is the definitive determinant. 1
• Do not require multiple azoospermic specimens when a single properly-performed analysis shows azoospermia or RNMS; this decreases patient compliance without improving safety. 3, 4, 5
• Counsel patients that even after confirmed sterility, vasectomy is not 100% reliable; late recanalization can occur years after confirmed azoospermia in approximately 1 in 2,000 men. 1, 2
• Warn patients about the <1% risk of requiring repeat vasectomy when proper occlusion techniques are used. 1, 2