Preferred Method for Accurate Semen Analysis
The preferred method for accurate semen analysis is adherence to World Health Organization (WHO) standardized laboratory procedures using manual microscopy or validated Computer-Assisted Sperm Analysis (CASA) systems, with the specimen examined fresh and uncentrifuged within 1-2 hours of collection. 1, 2
Critical Collection and Handling Requirements
The accuracy of semen analysis depends fundamentally on proper specimen collection and handling:
- Abstinence period: 2-3 days before collection 1
- Collection method: Masturbation or intercourse using semen collection condoms 1
- Transport conditions: Keep specimen at room or body temperature during transport 1
- Time to examination: Within 1 hour for fertility evaluation 1 or within 2 hours for post-vasectomy analysis 1
- Specimen preparation: Fresh, well-mixed, uncentrifuged sample 1
Laboratory Methodology Standards
The single most important factor determining accuracy is strict adherence to WHO standardized methods, not the type of equipment used. 2, 3
Manual Microscopy vs. CASA Technology
- WHO establishes reference methods and quality standards rather than endorsing specific machines 2
- CASA systems can be used if properly validated for the specific laboratory setting and sample type, with well-trained staff to identify and correct errors 2
- Manual microscopy remains widely accepted in clinical practice despite CASA availability 4
- The primary cause of semen analysis variability is laboratory failure to adhere to WHO methods, not equipment limitations 2, 3
Essential Quality Control Measures
Poor adherence to WHO standardized methods is a major problem across andrology laboratories worldwide. 1, 3
Quality control programs from Belgium, Germany, and Italy document that many laboratories fail to follow WHO protocols:
- Laboratories must demonstrate documented quality control procedures 3
- Validation is required for each specific laboratory setting when using CASA systems 2
- ISO 15189 accreditation to WHO standards is recommended but only achieved by a fraction of laboratories 1
Number of Analyses Required
Two semen analyses performed at least one month apart are recommended for initial male infertility evaluation. 1
However, the approach differs based on clinical context:
- For initial referral to infertility investigation: A single properly performed analysis is sufficient 3
- If abnormalities are found: Repeat analysis should be performed, particularly for results in the "intermediate" range 3
- Repeat testing should occur at a laboratory with documented quality control procedures following current WHO 2010 (or later) standardized procedures 3
Critical Parameters to Assess
A complete semen analysis must evaluate 1:
- Ejaculate volume (1.5-5.0 mL)
- pH (>7.2)
- Sperm concentration (>20 million/mL)
- Total sperm number (>40 million/ejaculate)
- Motility (>50%)
- Forward progression (>2 on 0-4 scale)
- Morphology (varies by WHO vs. Kruger criteria)
Important Limitations and Pitfalls
CASA cannot predict fertility outcomes from a semen sample alone but provides quality assurance data when carefully validated 2
Common pitfalls to avoid:
- Centrifugation interferes with sperm motility assessment and should not be used for routine analysis 1
- Substantial overlap exists in semen parameters between fertile men and those in infertile couples, meaning results cannot definitively determine fertility status 1
- Semen analysis is only part of the male evaluation and must be interpreted alongside history and physical examination findings 1
- Home-based testing devices lack the standardization and quality control of laboratory-based methods 5