Understanding Your Results

Other important semen analysis parameters

Differential Motility: what does it mean?

This is when sperm are classified as having no movement (immotile), having movement but not moving forward (non-progressive) or are moving and making some forward progression (progressive). The motility parameter is the combination of percentages for progressive and non-progressive sperm, and this value is considered normal if it is over 40%. The progressive motility alone should be at or above 32% to be considered normal. The speed of movement is not considered, as sperm will become hyperactive when exposed to fluids from the female tract and thus speed without this exposure is less important.


The percent motility can be increased in a sample being prepared for IUI by using an Isolation gradient wash that “filters out” many of the non-motile sperm, as well as other undesirable components of the semen sample.

Other important semen analysis parameters:



Two Important Calculated Values:


Total Count (TC)

The total count is the total number of sperm in the entire specimen/ejaculate. Calculated by multiplying the parameters of volume (mL) and density (Mil/mL). The units of the final number are in millions (Mil).

Ex. 2.0 mL X 45.0 Mil/mL = 90 million = TC


Total Motile (TM)

The total motile is the total number of sperm in the specimen/ejaculate that are “swimming”, or motile. This is perhaps the most important number of the semen Morphology

This parameter describes the percentage of sperm that have a normal appearance. It can be done through estimation or by staining the sperm and examining at a higher magnification. The latter is referred to as Strict Morphology, and there are a variety of systems used for this classification that are all based on comparing sperm in the sample to a set of strict criteria. The Kruger method of Strict Morphology is the most common, and is described in the WHO laboratory manual and is used by the majority of laboratories. This method involves staining the sperm on a slide and viewing it at 1000X with refraction oil to carefully examine the head, midpiece and tail of the individual sperm. The process involves assessing 200 sperm and then determining a percentage (%) of normal sperm, which are those that do not have visible defects. A morphology at 4% or higher is considered normal under the WHO 5th edition (2010) with a score of 3% considered borderline low. Older versions of the WHO manual have used cutoffs of 5% to 50% and thus this must be considered when interpreting results. The Krueger Strict Morphology assay is included in all complete (comprehensive) semen analyses at AALC.


Estimated Morphology

A general estimate of the percentage of apparently normal sperm forms seen, estimated morphology is a somewhat subjective parameter. If large numbers of a particular type of abnormal form are observed, the abnormal form/defect may be noted in the comments section of the report. A rating of 50% or greater is considered normal. To critically examine the morphology, sperm need to be stained and individually compared to a set of strict criteria. This is the Strict Morphology assay. An isolation wash will generally improve the overall morphology of the recovered sperm, as well as the motility of the final sample ready for IUI. Estimated morphology is used on Post Vasectomy Reversal Semen Analyses at AALC.



Days of Abstinence

Should be between 2 to 3 days – no more than 5 days. Longer or shorter periods can affect all the critical parameters mentioned above, usually making them lower, and are taken into consideration by the clinician if there are abnormal parameters.




Semen should liquefy within one (1) hour of collection. Failure to liquefy is considered abnormal and is noted on the report. The lab rates the viscosity or thickness or consistency of the sample as normal or abnormal based on how it flows drop-by-drop. A normal sample that is not hyperviscous flows easily and has threads trailing the drop of less than 2 cm. A hyperviscous sample has threads longer than 2 cm or flows in one continuous string, and is considered an abnormal parameter. Hyperviscosity can affect the reporting of density and motility, and so any treatments used to reduce viscosity to increase accuracy of the results will be noted in the comments section. This comment will typically also include the density and motility before any viscosity treatment was performed as a basis of comparison.



Indicates motile sperm sticking together in clumps, not involving dead sperm or other cellular components. Is graded on a scale of 0 to 4 (0,1,2,3,4) based on the frequency of the agglutinates (clumps of motile sperm) and the average number of sperm caught up in them. A rating of 0 or 1 is considered normal. Higher ratings of agglutination can indicate the presence of antisperm antibodies.

This is not the same as the parameter “Clumping” which is based on clumps of non-motile sperm or motile sperm clumped with dead sperm or cellular debris.


Round Cells (RC)

Round cells are just that – cells other than sperm found in an ejaculate that are basically round in shape. They may be white blood cells (WBC’s), immature sperm cells or perhaps other cellular components. They are all grouped together as round cells since it requires a special stain to differentiate the WBC’s from the immature sperm cells or to identify the types of WBC’s. Round cells are reported based on a calculation involving the number of RC’s seen compared to the number of sperm and the sperm density. A rating of zero (0) RC’s is considered normal.

A large number of round cells may indicate an infection (since many of the round cells may be WBC’s) or testicular dysfunction. Samples with large numbers of RC’s are also good candidates for Isolation gradient washes to help “clean up” the sample before an IUI.

 Some labs report this parameter as a range of RC’s seen per high power field (HPF), i.e. 0-5 RC/HPF. Anything less than 7 RC/HPF is considered normal.



The acidity/alkalinity of a semen sample is measured using pH test strips. A pH above 7.2 is considered normal. Semen should be alkaline so that it neutralizes the acidity of the vaginal pH. A low pH (acidic pH) can be indicative of a prostate dysfunction, as the prostate is the source of the alkalinity of semen.



Colonies of bacteria in semen can often be visualized even under 400X power, and are usually seen as tiny rods or cocci. The presence of bacteria is noted in the comments section of the report if any are seen in the sample. The presence of ANY amount of bacteria is considered abnormal.



Semen varies in color, from pale white or opaque to clear or pale yellow. Pink, red or brown coloration can indicate the presence of blood, and is considered abnormal. A very “clear” or translucent sample can be indicative of a low sperm density.



analysis as it is a composite of the three main parameters. The TM also shows the minimum number of living sperm, as some sperm may be alive but not moving (immotile). The decision of whether to continue trying for natural conception, consider an intrauterine insemination (IUI) or move forward with in vitro fertilization (IVF) with or without intracytoplasmic sperm injection (ICSI) is often based on the total motile sperm count of a semen specimen. Calculated by multiplying volume (mL), density (Mil/mL) and motility (%), or by multiplying the total sperm count (TC) by the motility (%).

Ex. 2.0 mL X 45.0 Mil/mL X 0.65 (aka 65%) = 58.5 million = TM


Other semen analysis parameters:



Clumping is when non-motile sperm are stuck together or when motile sperm are stuck to non-motile sperm, cellular components, or debris. This parameter is less relevant (and is not reported by our lab) due to the natural tendency of dead sperm to clump together or stick to debris. This parameter is graded on a scale of 0 to 4 (0,1,2,3,4) and a rating of 0 or 1 is considered normal. Some minor clumping is not unusual. Clumping, like agglutination, can affect the reporting of density and motility. Isolation washes can remove clumps and Chymotrypsin washes can break up the motile sperm stuck in the clumps.



Less important, and not include on our reports. Semen should have a distinct “spermine” odor, and any strong or foul or pungent odor can indicate a long interval between time of collection and time delivered to the laboratory. Other factors can affect odor as well. This is a subjective parameter as well.



Includes anything observed in the semen that cannot be identified as sperm, round cells, or other common cellular components. Graded on a scale of 0-4 with a grade of 0 or 1 considered normal. Isolation washes will remove most debris from a sample. This parameter is not included on our reports.



Other ways of reporting on semen analysis (not used at AALC):


The biggest difference between reporting methods is that the reference levels/ranges are different. For example the WHO Laboratory Manual for the Testing and Processing of Human Semen 5th Edition (2010) uses a lower reference limit (with no upper bounds) whereas the WHO 4th Edition (1999) uses a range that includes a lower and an upper bound. The values that determine whether a parameter is out of range or within normal range also differ between reporting methods. In the WHO 5th, for a density to be normal it needs to be above 15 million sperm per milliliter (Mil/mL) whereas the WHO 4th uses a lower bound.....


Forward Progression (FP)

This is a method of rating sperm motility based on the speed and straightness of movement, and is used instead of the differential motility breakdown (progressive, non-progressive immotile). Instead, the average speed/straightness of the sperm are graded on a scale of 0 to 4.0 with increments of 0.5. The normal range is considered to be FP=2.5 or 3.5 in unwashed specimens. The FP is a subjective scale as it is merely an estimate of the overall motion of the motile sperm from an examination of the slide. This grading scale is not used by AALC, but here is a breakdown of what each rating means and how it is estimated in case the lab you are using reports with this grading scale. Note that a FP of 0 or 1.0 is not subjective.


0          The motility is 0%. None of the sperm are motile or moving. If the motility is 0%, the FP will automatically be 0. Not subjective.


1.0       Some sperm are motile, but none of them are moving ahead or showing any signs of forward progression. All the motile sperm are just “twitching” or “moving in place”. Not subjective.


1.5       A few of the motile sperm are making some forward motion or progression, but it is very slow or “sluggish”. The rest of the sperm are either immotile or have FP=1.0.


2.0       Most of the motile sperm are moving forward in a slow or “sluggish” manner. A few might have a FP = 1.5 or 2.5, but the majority are moving slowly.


2.5       The majority of sperm have good, normal rapid progression in a forward direction. A few might have FP=2.0 or 3.0 or move in a circular motion, but most simply have normal progression.


3.0       Most of the sperm have very rapid forward progression.


3.5       Most of the sperm have extremely rapid forward progression and appear to be hyperactive. A FP of 3.5 is usually only seen after a sample has been washed.


4.0       All of the motile sperm have extremely rapid forward progression. Very rare, and usually only associated with sperm that have been washed/processed.


In short, a Forward Progression grade of 0, 1.0, 1.5, or 2.0 is abnormal, while a rating of 2.5 or better is considered normal. Semen processed with a Soft Wash or Isolation Wash usually have sperm with better forward progression in the final IUI preparation since many of the slower or non-motile sperm are “filtered out” or have been activated to a level of hyperviscosity typically only seen when exposed to fluids from the female tract.