What Is Agglutination in Sperm? – Causes, Symptoms & Treatment

By (embryologist), (embryologist) and (invitra staff).
Last Update: 02/10/2021

In addition to basic semen characteristics such as concentration, motility, and morphology of spermatozoa, other factors that may influence male fertility such as sperm agglutination are studied in the semen analysis.

Agglutination in sperm may indicate infertility of immunological origin, which is why it is an important factor to consider when looking for an infertility diagnosis.

Having said that, there are different degrees of agglutination with more or less severe consequences for a man’s fertility and future pregnancy.

What is agglutination in sperm?

When a microscopic analysis of the semen is performed, it can be observed if there are motile spermatozoa adhered to each other, which is called sperm agglutination.

Depending on this semen parameter, the result of the semen analysis should indicate if the sample shows:

  • Positive agglutination: which means that motile spermatozoa have been observed sticking together forming clusters.
  • Negative agglutination: motile sperm are not attached in the ejaculate sample tested.

This union of motile spermatozoa can be head to head, tail to tail, or even mixed.

Sperm agglutination classification

There are different grades of sperm agglutination, depending on the number of sperm attached:

Grade 1
There are less than 10 sperm per agglutination and many free sperm.
Grade 2
Each agglutination consists of 10-50 spermatozoa, but there are free spermatozoa.
Grade 3
Agglutinations are formed by more than 50 spermatozoa and there are few free spermatozoa.
Grade 4
All spermatozoa are agglutinated and the agglutinations are interconnected.

A high percentage of sperm agglutination can be a cause of male infertility, since sperm adhesion hinders their progressive movement and, therefore, prevents fertilization from occurring. If the sperm cells do not move through the female reproductive tract, they will not be able to meet the egg and pregnancy will not occur.

Agglutination or aggregation?

Although it is true that sperm agglutination and sperm aggregation may seem to be the same thing, there are differences between the two concepts.

  • Agglutination. We speak of agglutination when motile sperm have joined together.
  • Aggregation. We speak of aggregation when immotile sperm cells are attached to each other, or motile sperm are attached to mucus, other cells or cellular debris.

Sperm aggregation is more non-specific in nature and is therefore of less clinical relevance than motile sperm agglutination.


Sperm agglutination may suggest the presence of anti-sperm antibodies in the ejaculate. These molecules recognize the membranes of the spermatozoa and bind to them, forming agglutinations. This can lead to the so-called immunological infertility.

In addition, there are other possible causes of sperm agglutination:

  • Very high concentration of sperm in the ejaculate.
  • Changes in the pH of the semen due to problems in the accessory glands (due to inflammatory or infectious processes).
  • Increased body temperature during febrile processes.
  • Certain types of bacteria can cause agglutination in semen.

Although the male may have some of these conditions, it does not automatically mean that agglutination is found in the semen analysis.


In cases of agglutination due to febrile or infectious processes, this should disappear on its own after treating the infection and allowing a reasonable amount of time to pass.

The most common thing to do is to repeat the semen analysis after the treatment and analyze carefully if the sperm agglutination has been fixed.

Possible cure

Mild or moderate cases of sperm agglutination can be treated with various medications to see if it lessens or even goes away. Vitamin preparations are recommended, especially vitamin C, which activates the anti-agglutinin protein.

In severe cases, however, it is possible that the agglutination in sperm cannot be treated. In cases of severe sperm agglutination, it is best to resort to assisted reproduction treatments such as ICSI (intracytoplasmic sperm injection) to achieve pregnancy.

Considering seeing a fertility specialist? Don't forget that, in the field of Reproductive Medicine, as in any other medical area, it is crucial that patients rely on the doctors and staff that will help them through their treatment cycle. Logically, conditions vary from clinic to clinic. For this reason, we recommend that you generate your Fertility Report now. It will offer you a list of clinics that have passed our rigorous selection process successfully. Furthermore, the system will make a comparison between the fees and conditions of each clinic so that you can make a better-informed decision.

In the andrology laboratory, sperm capacitation is performed, where motile sperm that are able to move progressively are separated from the rest (agglutinated and immotile sperm). The specialist will select the best spermatozoon from among those obtained in the sperm capacitation to introduce it into the egg.

FAQs from users

Is sperm agglutination always analyzed in a sperm test?

By Silvia Azaña Gutiérrez B.Sc., M.Sc. (embryologist).

Sperm agglutination is a parameter that is always taken into account when performing the microscopic examination of a semen analysis.

If agglutination is observed when a semen sample is analyzed under the microscope, the specialist should note it in the report. In addition, the degree of agglutination and the type of sperm union (e.g., grade 2, head-head unions) should be included.

Is sperm aggregation something serious?

By Silvia Azaña Gutiérrez B.Sc., M.Sc. (embryologist).

Sperm aggregation is nonspecific, as immotile sperm bind to each other or motile sperm to detritus or other cell types. This makes it of little clinical relevance, unlike agglutination.

Suggested for you

If you want to learn more about semen analysis, we recommend you to have a look at this post: What Is a Semen Analysis Report? - Purpose, Preparation & Cost

A possible solution for sperm agglutination is ICSI. If you want to have more in-depth information about this treatment, you can visit this article: What Is ICSI Technique? - Process, Success Rates & Cost

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Authors and contributors

 Neus Ferrando Gilabert
Neus Ferrando Gilabert
B.Sc., M.Sc.
Bachelor's Degree in Biology from the University of Valencia (UV). Postgraduate Course in Biotechnology of Human Assisted Reproduction from the Miguel Hernández University of Elche (UMH). Experience managing Embryology and Andrology Labs at Centro Médico Manzanera (Logroño, Spain). More information about Neus Ferrando Gilabert
 Silvia Azaña Gutiérrez
Silvia Azaña Gutiérrez
B.Sc., M.Sc.
Graduate in Health Biology from the University of Alcalá and specialized in Clinical Genetics from the same university. Master in Assisted Reproduction by the University of Valencia in collaboration with IVI clinics. More information about Silvia Azaña Gutiérrez
License: 3435-CV
Adapted into english by:
 Romina Packan
Romina Packan
inviTRA Staff
Editor and translator for the English and German edition of inviTRA. More information about Romina Packan

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