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Semen analysis
Semen analysis (seminogram) evaluates male fertility by assessing sperm count, motility, morphology, and other parameters. The WHO 2021 reference values set lower reference limits including: volume ≥1.4 mL, total sperm count ≥39 million, progressive motility ≥30%, and normal morphology ≥4% (Kruger strict criteria).
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"semen analysis" AND "reference values"
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Here is a thorough overview of semen analysis drawn from multiple authoritative textbooks:
Semen Analysis (Seminogram)
Semen analysis is the primary and most important investigation in the evaluation of male infertility. It assesses sperm production, transport, and function, though it is not a direct measure of fertility. - Harrison's Principles of Internal Medicine 22E, p. 2701
Indications
- Evaluation of male infertility (the primary use)
- Selecting sperm donors for therapeutic insemination
- Monitoring success of surgical procedures (e.g., varicocelectomy, vasectomy)
- Post-vasectomy confirmation of sterility
Sample Collection
- Sexual abstinence: 2-3 days recommended before collection. Longer abstinence (>5 days) increases count but reduces motility. - Smith and Tanagho's General Urology, p. 724
- Method: Masturbation (preferred); coitus interruptus or a non-spermicidal condom are acceptable alternatives.
- Container: Sterile plastic (polypropylene) with a screw-top lid.
- Transit: Deliver to lab within 1 hour of collection; keep at body temperature.
- Minimum specimens: At least 2 samples, collected 2-3 weeks apart, are needed to establish a baseline. Markedly different results warrant additional specimens.
- Incomplete specimens must not be analyzed.
Macroscopic Examination
Performed after liquefaction (normally within 15-30 minutes at room temperature).
| Parameter | Normal Range |
|---|---|
| Appearance | Gray-white, opalescent |
| Liquefaction | ≤30 minutes |
| Volume | ≥1.5 mL |
| pH | 7.2-7.8 |
| Viscosity | Normal (non-hyperviscous) |
Interpretive notes:
- Low volume (<1.5 mL): Retrograde ejaculation, ejaculatory duct obstruction, incomplete collection, or androgen deficiency. If no sperm are seen with low volume, a fructose test confirms seminal vesicle contribution.
- Yellow hue: Associated with pyospermia (pus cells).
- Rust color: Small bleedings in the seminal vesicle.
- pH >8.0: Acute infection (prostate, seminal vesicle, epididymis).
- pH ≤7.0: Urine contamination, ejaculatory duct obstruction, or predominantly prostatic fluid.
- Failure to liquefy: Suggests inadequate prostate secretion.
Microscopic Examination
WHO 2010 Reference Limits (5th Percentile of Fertile Men)
Based on semen data from >4,500 men in 14 countries whose partners conceived within 12 months. - Harrison's 22E, p. 2702
| Parameter | Lower Reference Limit |
|---|---|
| Semen volume | ≥1.5 mL |
| Total sperm number | ≥39 million/ejaculate |
| Sperm concentration | ≥15 million/mL |
| Total motility (progressive + non-progressive) | ≥40% |
| Progressive motility | ≥32% |
| Vitality (live sperm) | ≥58% |
| Morphologically normal forms | ≥4% (Kruger strict criteria) |
| Leukocytes | <1 × 10⁶/mL |
Motility Grading
- Grade 4: Rapid, straight-line movement with little yaw
- Grade 3: Slower linear movement
- Grade 2: Slow, substantial yaw - no real forward progression
- Grade 1: Twitching but no forward motion
- Grade 0: No movement at all
If motility is <30%, a viability stain (eosin Y with nigrosin counterstain) is performed. Dead sperm stain red; live sperm exclude the dye and appear unstained. - Henry's Clinical Diagnosis, p. 496
Morphology (Kruger Strict Criteria)
- At least 4% of sperm must have normal morphology.
- Strict criteria assess the head, midpiece, and tail dimensions precisely.
- >4%: Excellent fertilizing capacity
- 0-3%: Predicts probable inability to fertilize (in vitro and in vivo)
- The most common abnormality: wide variability in acrosomal cap size; an acrosomal cap <1/3 of head surface is abnormal.
- Teratozoospermic index (TZI): Average number of defects per sperm - a significant predictor of sperm function. - Henry's Clinical Diagnosis, p. 497
Agglutination
Motile sperm sticking to each other in a reproducible pattern (head-to-head, tail-to-tail, midpiece-to-midpiece). Suggests immunologic infertility and should be distinguished from non-specific clumping due to infection or debris.
Round Cells
Two types must be differentiated:
- Immature germ cells: Large cytoplasm, condensed single/double nucleus
- Polymorphonuclear leukocytes: Smaller, lower nuclear:cytoplasmic ratio
Peroxidase staining specifically identifies PMNs. Leukocytospermia (pyospermia) is defined as >1 × 10⁶ leukocytes/mL. Among leukocytes, neutrophils predominate. - Smith and Tanagho's Urology, p. 725
Nomenclature for Abnormal Results
| Term | Meaning |
|---|---|
| Azoospermia | No sperm in ejaculate |
| Oligozoospermia | Sperm concentration <15 million/mL |
| Asthenozoospermia | Progressive motility <32% |
| Teratozoospermia | Normal morphology <4% |
| Oligoasthenoteratozoospermia (OAT) | Combined defect in count, motility, morphology |
| Leukocytospermia / Pyospermia | Leukocytes >1 × 10⁶/mL |
| Hypospermia | Volume <1.5 mL |
Frequency of Abnormal Findings in Infertile Men
From Smith and Tanagho's Urology, p. 724:
| Finding | % of Infertile Men |
|---|---|
| All normal | 55% |
| Low motility | 26% |
| Low count | 8% |
| No sperm (azoospermia) | 8% |
| Abnormal volume | 2% |
| Abnormal morphology alone | 1% |
Computer-Assisted Semen Analysis (CASA)
CASA uses video + digitalization to objectively categorize sperm features. Limitations:
- Can overestimate sperm counts by 30% when contaminating cells (immature sperm, leukocytes) are present.
- Can underestimate motility at high sperm concentrations.
- Accepted in research settings and select clinical labs. - Smith and Tanagho's Urology, p. 725
Immunologic Tests (Antisperm Antibodies - ASAs)
- ASAs can be found in serum, seminal plasma, or bound to sperm; sperm-bound antibodies are the most clinically relevant.
- Main classes: IgA and IgG (IgA is most significant).
- Detected by: Direct or indirect MAR (Mixed Agglutination Reaction) test or immunobead assay.
- Both tests require motile sperm. The direct MAR test is performed on fresh semen.
Additional Tests When Indicated
- Fructose test: If azoospermia with low volume - confirms presence of seminal vesicle secretion; a negative fructose test + azoospermia = ejaculatory duct obstruction.
- Post-ejaculate urinalysis: If retrograde ejaculation is suspected.
- Y-chromosome microdeletion testing: In non-obstructive azoospermia or severe oligozoospermia (<5 million/mL). Regions tested: AZFa (sY84/sY86), AZFb (sY127/sY134), AZFc (sY254/sY255).
- Testicular biopsy: In azoospermia/oligospermia to distinguish obstructive from non-obstructive causes and to harvest sperm for ICSI.
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