Sperm Morphology: All About Normal & Abnormal Sperm Morphology

A sperm morphology is primarily investigated to check the fertility status of a man along with sperm count and motility. To understand this, we need to perform a semen analysis test. One of the important parameters in the test is the morphology that is shape and size of the sperm. The shape of the sperm gives us an insight that a proper sperm development or spermatogenesis has happened in the testicles. Men with a defect in sperm maturation tend to have problems with sperm shape and that may in turn affect male fertility.

Sperm morphology
Sperm morphology
  • What is Sperm Morphology?

    Sperm Morphology refers to the shape and size of the sperm as observed under a microscope. It basically looks at the shape and appearance of the sperm head, midsection, and tail. The head shape is most important because it carries the genetic information and affects the sperm’s ability to dissolve the outer surface of an egg and fertilise it. The mid-piece contains enzyme and multiple mitochondria which supplies energy to the sperm for the journey through the female cervix, uterus and uterine tubes. The tail is made up of protein fibres and helps the sperm to swim forward in the female genital tract to meet the egg.

    Morphology is one of the important factors that is examined as a part of semen analysis test to evaluate male infertility along with sperm count and sperm motility. The results are reported as the percentage of sperm that appears normal when semen is viewed under a microscope. Traditionally, male fertility investigation relies on this standardised analysis of the semen parameters (morphology, motility, count). And the diagnosis is dependent on the microscopical assessment and biochemical assays which determines the quality of the semen.


    Sperm Cell Anatomy

    Sperm cell anatomy
    Image of a normal sperm

    Sperm Morphology Test

    A Sperm Morphology can be seen in a semen analysis test also known as the sperm count test. A semen analysis test analyses the health and viability of a man’s sperm. For a semen analysis test, we need a fresh semen sample from patient. Semen is the fluid containing sperm (plus other sugar and protein substances and secretions from other male accessory glands) that is released during ejaculation, and its main function is to fertilise a female ova or egg. From that semen sample, a drop of semen is taken in a clean dry glass slide, it is then dried, stained and observed under a microscope to determine the percentage of normal sperm in the total sample taken. A man should at least, give two semen samples a few days apart to get an accurate result of semen analysis which determines the sperm quality.

    A normal sperm morphology can range from 4 to 14 percent. The fertility rate is considered good, when normal sperm morphology is in this range. A sperm morphology, lower than 4 percent means it will take longer time to impregnate a female.

    W.H.O. 2010 cutoff parameters for a normal sperm count

    Parameter Lower Reference limit
    Semen volume (ml) 1.5
    Sperm Concerntration (106/ml) 15
    Total Sperm Number (106/ejaculate) 39
    Progressive motility (PR, %) 32
    Total Motility (PR +NP, %) 40
    Vitality (live sperms, %) 58
    Sperm morphology (NF, %) 4
    pH* >/=7.2
    Leucocyte* (106/ml) <1
    MAR/Immunobead Test* (%) <50

    *Parameters agreed on consensus

    W.H.O. 2010 cutoff parameters for a normal sperm count
    Normal Sperm Test Result (W.H.O. Report)

    Normal sperm morphology

    Normal sperm has an oval head with a long tail. It should be free from any defect to fall under the category of normal sperm morphology.

    • The head should be smooth and between 2.5 to 3.5 micrometres wide and 5 to 6 micrometres long.
    • An acrosome tip that takes 40 to 70 percent space of the head of the sperm. The acrosome is a unique membranous organelle located over the anterior part of the sperm nucleus that contains enzymes which helps to penetrate an egg’s membrane.
    • The head should not have a large fluid filled vacuole, also should not contain more than two small vacuoles and should not occupy more than 20 percent of the total head.
    • The area between the head and the tail known as the midpiece should be thinner than the head.
    • A straight non-defective tail that is 45 micrometres long and should be thinner than the head and the midpiece.

    With Strict criteria or Kruger’s criteria a score of 4 to 14% sperm of normal morphology are considered sufficient to achieve a pregnancy.

    Abnormal sperm morphology

    Teratozoospermia, teratospermia or abnormal sperm morphology is a semen alteration in which a large percentage of sperm have an abnormal shape.

    • Abnormal sperm have large or deformed heads


      Head Defects of Sperm
      Head Defects of Sperm
    • The midpiece may be defective


      Midpiece Defects of Sperm
      Midpiece Defects of Sperm
    • Crooked or double tails


      Tail Defects of Sperm
      Tail Defects of Sperm
    • And at times large vacuoles may be present.

    Abnormal Sperm Morphology

    Head defects Includes large, small, tapered (elongated), pyriform (pear shaped), round, and amorphous (constricted) heads, vacuolated, heads with small cap area (< 40% of the head area) and double heads, as well as combination of these. Globozoospermia, where the head appears small and round due to the failure of the acrosome to develop.
    Midpiece defects Includes bent neck, asymmetrical insertion of the midpiece into the head, irregular midsection, an abnormally thin and thick midsection, cytoplasmic droplet as well as a combination of these.
    Tail defects Includes short, multiple, hairpin, broken or bent tails, coiled tails and terminal droplet, as well as a combination of these

    Traditionally, teratozoospermia was diagnosed if 14% of the sperm had normal shape. According to W.H.O. guidelines 2010, the reference value was updated. A man should have 5% of properly shaped sperms, to be within normal limits. By current standards if a man is diagnosed with teratozoospermia, 96% of his sperms need to be morphologically abnormal.

    Strict morphology or Kruger morphology score 0 to 3% is considered abnormal which means a very severe impairment or inability to fertilise.

    Kruger Morphology

    Strict morphology or Kruger morphology is a useful test to be performed with couples who have unexplained infertility, even when the semen analysis and non-strict morphology are normal. If a man has decreased number of normally shaped sperm on the Kruger strict morphology analysis, then he is at a risk of fertilisation failure or low rates of fertilisation.

    Abnormal sperm morphology and male infertility

    In order, for a man to be fertile only 4 to 14% of normal sperm is needed. Just having abnormal sperm won’t have any impact on fertility, there are other factors also, they are sperm numbers, sperm concentration, semen volume, the percentage of sperms that are alive (viability) and the ability to move (motility). An abnormally shaped sperm doesn’t mean that the genetic material it carries will be damaged, it is usually healthy. According to a 2017 study in Asian journal of andrology, men with 0% normally formed sperm had near normal fertility rates, which indicates there are other significant factors besides sperm morphology.

    And men with abnormal sperm morphology can impregnate a female. It means that he is not infertile, but he may need a longer time to make the female pregnant. If natural conception doesn’t occur, he will have the option of assisted reproductive technology like in vitro fertilisation with ICSI. ICSI is a process, where his sperms can be directly injected into the cytoplasm of an egg, ICSI stands for Intracytoplasmic sperm injection. The advent of ICSI has furthered reduced the significance and perceived need for sperm quality tests because ICSI requires only one sperm to fertilise the egg. ICSI can be done when sperm morphology is less than 2%.

    If sperm concentration and sperm motility are normal or high it may be advisable and reasonable to consider IUI before ICSI-IVF.

    Sperm morphology improvement

    Sperm is usually healthy when a man is young. A major contribution to good sperm morphology will depend on genetic factors and the age of the man. If he is delaying in starting a family, and at that time if he comes to know that his sperm morphology range is low, it will be too late. A good option for him would be freezing his sperm which can be used in future.

    A man’s body is always producing new sperm, so changes in diet or lifestyle may impact the health of a future sperm. Some lifestyle management like losing weight, exercising regularly, avoiding heavy drinking, smoking, taking drugs, wearing lose cotton shorts may improve sperm quality. Being exposed to chemicals or radiation at work or in home can also affect sperm quality and hence in turn fertility. Some natural supplements and vitamins may help in promoting natural sperm morphology.

    Sperm Morphology Success Story – Savita (34) and Nitin (37) had been trying to conceive for almost a year.

    “I was regularly tracking my cycles, could very well monitor my ovulation and my periods were bang on time. I had no other medical history that could affect my chances of getting pregnant. This kept me and Nitin thinking the cause behind my not being able to conceive even after so much time had passed. We thought of visiting an infertility clinic, after some research and comparing the success rates of a few clinics we zeroed down on Medicover Fertility. There we met Dr. Sweta Gupta (Clinical Director – Medicover Fertility) who recommended a semen analysis test for my husband Nitin. The test result showed he had a slight low sperm count, but the biggest issue was that 98% of his sperm had abnormal morphology. Mostly the heads were deformed.

    Dr. Gupta told us that natural pregnancy though possible might take too long for us. She didn’t recommend IUI (Intrauterine insemination) because it is not successful with men who have abnormal morphology. Keeping our age in mind and after consulting with an embryologist she suggested ICSI (Intracytoplasmic sperm injection) with IVF (In vitro fertilisation), because that was the only option available for us, as ICSI only requires a single healthy sperm to fertilise an egg.”

    And thanks to Medicover Fertility, we are proud parents to twin boys today.


    How can Medicover Fertility help you with an abnormal sperm morphology?

    Medicover Fertility is a renowned international brand. We have a team of highly skilled and experienced doctors who help couple dealing with infertility. Medicover Fertility has a very high fertility success rate as we use the latest technology in fertility treatments. Here the couples are carefully examined to find out the actual cause of infertility.

    Receiving a diagnosis of male infertility can be emotionally disturbing. Best is to speak to a doctor who will recommend a treatment plan. Dr. Sweta Gupta (Clinical Director, Medicover Fertility) has over 23 years of experience in infertility. A lot of cases with abnormal sperm morphology are dealt in Medicover Fertility. The advent of ICSI has almost solved this problem of abnormal sperm morphology, men with less than 4% normal forms of sperm are able to father a child, however performing an ICSI is a call taken by the doctors after consulting with embryologists. They will chalk out the best treatment plan by looking at the medical history.

    Related questions: –

    Q) Can an abnormal sperm fertilise an egg?

    A) It’s possible for an abnormally shaped sperm to fertilise an egg, having an abnormal sperm morphology doesn’t mean that a man would be completely unable to impregnate the female, he might take a longer time to do so. The genetic material in that abnormal sperm may be healthy.

    Q) Does sperm quality affect a baby?

    A) A sperm with chromosomal abnormalities might cause a miscarriage. Sperm quality is good in younger men, with age sperm quality deteriorates in a man, hence the chances of a baby born with genetic defects are there in older men.

    Q) Can unhealthy sperm cause pregnancy?

    A) Unhealthy sperm where the head is defective with altered genetic material, may not cause pregnancy instead may cause early miscarriage due to abnormality in chromosome.

    Q) Can you get pregnant if a man has low sperm count?

    A) Low sperm count also known as oligospermia is a common cause of subfertility or infertility in couples. Low sperm count does not necessarily prevent pregnancy from occurring, natural pregnancy may occur but may take some time.

    Q) What is sperm morphology normal values?

    A) A healthy or normal sperm morphology value can range from 4 to 14%. Fertility success is good, when the sperm is in this range.

    Q) Can 0% sperm morphology be improved?

    A) In couples with infertility, abnormal strict morphology of 0% normal forms of sperms, is a criterion to proceed rapidly towards in vitro fertilisation. Sperm quality may be increased by a good diet, and proper intake of vitamin supplements and antioxidants.

    Q) How bad is 1% sperm morphology?

    A) According to strict morphology or Kruger morphology, a score of 0 to 3% is considered abnormal which means a very severe impairment or inability to fertilise an egg.

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