Semen Analysis

A semen analysis is a laboratory test for men that accurately measures the quantity and quality of the semen and sperm within. This is sometimes called a sperm count test in layman’s terms and is usually performed to assess a man’s fertility or confirm successful vasectomy.

In preparation for this test men should:

• Abstain 2-7 days from ejaculation.
• Keep hydrated.
• Avoid catching a severe cold or flu 1-2 months prior.
• Check if you need to pause any medication.

This increases the chances of an accurate result and may avoid the need for a second semen analysis. On a second and subsequent semen analysis, experts recommend men try to abstain the same number of days as the previous test and produce a sample at the same time of day. Doing this reduces the number of variables that can significantly alter the results of a semen analysis and makes comparisons more accurate.

Normal Semen Analysis Test Results

The normal values for several parameters assessed in a basic semen analysis was recently updated in the 6^th edition of the WHO laboratory manual for the examination and processing of human semen.¹

The following table is an updated summary of what is normal for each parameter.

Interpreting Semen Analysis Test Results

An abnormal test result or individual parameter does not automatically mean the man is infertile

You may get an abnormal result for one or several of the following parameters:

• Time
• Liquefaction
• Appearance
• pH
• Volume
• Viscosity
• Sperm concentration
• Total sperm count
• Total sperm motility
• Progressive sperm motility
• Non-progressive sperm motility
• Immotile sperm
• Sperm Motility Index (SMI)
• Vitality or viability
• Sperm morphology
• Teratozoospermia Index (TZI)
• Cellular elements
  • Round cells
  • Red blood cells (RBC)
• Sperm Clumping
• Zinc
• Fructose

Time

Semen analysis should commence within 60 minutes of collection, but preferably within 30 minutes.

During this time the semen sample must not be allowed to go below 20 °C or above 37 °C if it is being transported to the laboratory.

If the semen analysis does not commence within 60 minutes of collection, results should be interpreted with caution and a second test is normally recommended to confirm any abnormal results.

Liquefaction

Normally semen begins to liquefy within a few minutes at room temperature. However complete liquefaction of semen normally takes between 15 to 30 minutes at room temperature.

If liquefaction is not complete within 30 minutes, the sample is left for another 30 minutes in an incubator at 37 °C. After 60 minutes, if liquefaction is still not complete, the result is recorded as abnormal.

It is normal for liquefied semen to contain a few jelly-like granules known as gelatinous clumps or bodies (or gel particles / pieces). The presence of these is not clinically relevant according to the evidence to date.

Appearance

Normal semen is a light cream/gray opalescent color that appears white to the untrained eye. The clarity of semen (turbidity) is normally opaque (i.e. not transparent).

Semen that is less opaque (translucent) could be a sign of low sperm concentration whereas totally clear and viscous appearing semen is most likely only pre-ejaculate fluid.

Semen usually appears slightly yellow after a long abstinence period. However, semen will also appear yellow in men with an infection, jaundice, after semen contamination or consuming certain foods, vitamins and drugs.

Semen that is a reddish brown or pink color normally means a large number of red blood cells are present (e.g. haematospermia). Although this can also be caused by certain foods and drugs sometimes. In rare cases semen may also appear very brown or black due to bleeding or non-bleeding causes.² Regardless of the cause medical attention is highly recommended.

pH

A normal semen pH is between 7.2 to 7.8. This value is strongly dependent on the relative contribution of secretions from the prostate (acidic) and seminal vesicles (alkaline).^3,4 The majority of men with high pH (>7.8) have normal sperm parameters.⁵ However, a high pH (>7.8) and abnormal sperm parameters is often a sign of infection (e.g. Chlamydia, COVID, Ureaplasma urealyticum, Prostatitis), whereas low pH (<7.2) and normal volume could be a sign of a blockage (seminal vesicles), or a genetic condition (Congenital Bilateral Absence of the Vas Deferens).^6,7,8

Volume

Normal semen volume is between 1.4 to 6.2 mL. This is normally measured by weight as other methods are less accurate.⁹

Semen volume < 1.4 mL is diagnosed as hypospermia. Assuming no semen was spilled during collection this indicates either an obstruction of the ejaculatory duct, partial retrograde ejaculation, androgen deficiency or congenital bilateral absence of the vas deferens.

Semen volume > 6.2 mL is diagnosed as hyperspermia. Assuming the abstinence period was not longer than 7 days, and semen volume is normally not that much (i.e. genetic condition), this indicates inflammation of the accessory glands.

Viscosity

Normal viscosity (or viscous) is when liquefied semen falls as small drops from a wide bore pipette under gravity. Abnormal viscosity is when each semen drop forms a thread longer than 2cm. This is sometimes described using numbers (e.g. 3+, 4+) which represent the apparent length of the semen drops during viscosity testing.

Sperm Concentration

Sperm concentration is the number of sperm per milliliter of semen. This number is manually or automatically calculated from at least 2 counting slides.

Normal sperm concentration is ≥ 15 million per mL. However, sperm concentration is more variable than total sperm count since semen volume is mostly made up of secretions from the seminal vesicles and prostate.

Total Sperm Count

Normal total sperm count is ≥ 39 million. Total sperm count is calculated from sperm concentration and semen volume (e.g. sperm concentration × semen volume).

Total sperm count is a reliable indicator of testicular function and its capacity to produce sperm. Total sperm count < 39 million is diagnosed as oligospermia (low sperm count).

Sperm Motility

Normal total sperm motility is ≥ 42%. Total sperm motility is a combination of progressive and non-progressive motility (e.g. progressive + non-progressive motility) although progressive motility is the most important.

Normal progressive sperm motility is ≥ 30% which consists of both rapid and slow progressive sperm (e.g. progressive sperm motility = rapid + slow progressive motility).

Although irrelevant for natural conception, normal non-progressive sperm motility is at least 1% or more. Non-progressive motility is sometimes described as no progression, sluggish, and equivalent to Grade C or Grade 1.

Similarly, normal immotile sperm is at least 20% or more, but also irrelevant unless diagnosing the possible cause of abnormal sperm motility. Immotile sperm is sometimes described as non-motile, immobile, and equivalent to Grade D or Grade 0.

Some laboratories also calculate a Sperm Motility Index (SMI). The Sperm Motility Index is a computer-generated value that correlates with motile sperm concentration. Normal Sperm Motility Index is any number from 80 to 300. This range represents a sperm concentration of 20 to 180 million sperm per mL.¹⁰

Vitality or Viability

Sperm vitality, also known as sperm viability, refers to the percentage of live sperm found in the semen sample. Normal sperm vitality (or viability) is ≥ 54%. Abnormal sperm vitality (<54%) is defined as necrospermia.¹¹ This test should be performed as soon as possible after liquefaction for accuracy.

Although if total sperm motility is ≥ 40%, sperm vitality or viability is normally not tested (i.e. n/a). Only if sperm motility is < 40% will sperm vitality or viability be checked to differentiate between immotile live sperm and immotile dead sperm.

A significant percentage (approximately 25-30%) of live but immotile sperm indicates potential structural defects in the tail.¹² On the other hand, a high percentage of dead sperm usually indicates an epididymal issue or infection.¹³

Sperm Morphology

The percentage of sperm with normal morphology is at least 4% or more among men who successfully conceive within 12 months. Although studies also show men abnormal sperm morphology are able to conceive naturally.

Normal sperm morphology is sometimes described as Strict Kruger morphology¹⁴, normal forms or ideal forms. Similarly, abnormal sperm morphology is sometimes described abnormal forms.

Some semen analysis provide further detail on sperm abnormalities according to 4 categories:

• Head
• Neck and midpiece
• Tail
• Excess residual cytoplasm

Note that sperm can have none, one or multiple abnormalities (i.e. defects). However, observing many sperm with a single abnormality normally indicates a structural defect (e.g. globozoospermia).

Abnormal sperm head (cephal) defects include tapered, pyriform, round (no acrosome or small), amorphous, vacuolated, small acrosomal area or double heads. Although abnormally large heads (macrocephalic) or small heads (microcephalic) are also not normal.

Along the neck and midpiece section possible defects include bent neck, asymmetrical, thick or thin insertion.

Meanwhile, possible tail (flagella) defects include either short, bent, coiled or multiple tails. Although tails coiled more than 360° suggest epididymal dysfunction.¹⁵

Lastly, excess residual cytoplasm is considered abnormal whenever it is larger than 1/3 of a normal sperm head, suggestive of a defective spermiation process.

It is also possible during the spermiation process that the tail fails to attach to the head and only sperm heads or tails are found in semen. Sometimes referred to as free sperm heads or free tails (or pinheads). This of course makes natural conception impossible.

Overall, thorough examination of sperm morphology is generally helpful when diagnosing possible male factor infertility.

Teratozoospermia Index (TZI)

The teratozoospermia index (TZI) is the average number of defects per abnormal sperm. The maximum number of defects is 4: head, midpiece, tail and residual cytoplasm. However, a normal TZI is usually between 1.17 to 2.07. Unfortunately, there is significant overlap between normal TZI (fertile) and abnormal TZI (infertile). Abnormal TZI ranges from 1.26 to 2.64 which makes interpretation of TZI challenging for doctors unless the result is at the extreme end of either the fertile or infertile range.

Total Motile Sperm Count

Total motile sperm count (TMSC) is proven to be a better predictor of spontaneous pregnancy than an individual semen parameter.¹⁶ This is because a man with an abnormal semen parameter could still have more than enough motile sperm to conceive naturally. A Total Motile Sperm Count (TMSC) greater than 20 million is considered normal. Or at least 14.3 million in terms of Total Progressive Motile Sperm Count (TPMSC).

Cellular Elements

Cellular elements (debris) other than sperm is sometimes described as background materials or contaminants. This includes non-sperm cells such as:

• Round cells
  • Inflammatory round cells. I.e. White Blood Cells (Pus Cells)
    • Polymorphonuclear leukocytes (neutrophils)LymphocytesMonocytesMacrophages
  • Non-inflammatory round cells
    • Immature germ (germinal) cells (e.g. spermatogonia, spermatocytes, spermatids)
    • Epithelial cells
• Red Blood Cells

Round Cells

Round cells describes both inflammatory or non-inflammatory cells found during semen analysis since it is not possible to differentiate them under microscope.¹⁷

If an abnormal amount of round cells (≥ 1 million per mL or 4 per HPF) is reported further testing is recommended to identify the quantity and type of cells and likelihood of infection (e.g. leukocytospermia, UTI, yeast infection).

Red Blood Cells

An abnormal number of red blood cells (erythrocytes) in semen, also known as hematospermia, is associated with infertility although this is not always visible by the naked eye.¹⁸ In fact, just 2 or more red blood cells per high power field (HPF) under microscope during semen analysis is considered abnormal.

Sperm Clumping

There are two different types of sperm clumping:

• Sperm aggregation
• Sperm agglutination

Sperm aggregation refers to immotile sperm stuck to each other or motile sperm stuck to mucus strands, non-sperm or debris (i.e. non-specific aggregation). Sperm aggregation should be reported as 0 (none), 1 (some) or 2 (plenty) although many laboratories still report aggregation as either absent (negative) or present (positive).

Sperm agglutination refers to motile sperm sticking to each other, in any way at the head, tail or mid-piece. Sperm agglutination can affect the assessment of sperm motility and concentration. This is sometimes caused by anti-sperm antibodies but further tests are required to confirm.

Sperm agglutination is normal (negative) if total sperm agglutination <2 on both counting slides. Meanwhile, sperm agglutination is abnormal (positive) if total sperm agglutination ≥2 on both counting slides. This can also be reported as the degree of agglutination:

• Grade 1. Isolated (< 10 sperm agglutinate)
• Grade 2. Moderate (10-50 sperm agglutinate)
• Grade 3. Large (>50 sperm agglutinates)
• Grade 4. Gross (all sperm agglutinated)

Zinc

Zinc is reliable measure of prostate gland function and secretion. Normal semen zinc levels is ≥ 2.4 µmol.

Fructose

Fructose in semen reflects the secretory function of the seminal vesicles. Normal semen fructose levels is ≥ 13 µmol. Some lab reports may only report fructose as present or absent.

After Semen Analysis

After completing a semen analysis, the doctor is usually able to advise if the results are normal or further tests are required.

This could include:

• Second semen analysis
  • If the results are borderline and or analysis was delayed.
  • If the results are abnormal but the man was also sick recently.
• Urine or semen culture test to rule out bacterial infection.
• Hormone tests to evaluate testicular function.
• Detailed morphological assessment.
• Sperm DNA fragmentation.
• Genetic testing (Karyotyping).
• CD45 LCA test to precisely quantify leukocytes.
• Papanicolaou staining to identify and quantify immature germ cells.
• Immunobead or mixed antiglobulin reaction test to rule out sperm antibodies.
• Spectrophotometric assay for zinc, fructose and α-glucosidase levels to check the accessory sex glands.

The results of these tests can help the doctor identify the cause of any abnormalities or unexplained infertility and guide treatment options.

Keep in mind it is common for the cause to remain unknown after extensive testing¹⁹ or the treatment plan to remain the same regardless of some test results. In these cases your doctor is more likely to recommend medically assisted reproduction (e.g. IUI, IVF, ICSI) instead of further testing.