By: Alysia McGlynn, BS and Meaghan Bowling, MD
Male fertility is evaluated via semen analysis. During this test, the patient’s semen is examined for color, viscosity, volume, concentration, total sperm count, sperm motility, and progression. After these characteristics are analyzed, our lab can also review the sample’s morphology (sperm size and shape). Abnormalities in shape make it more difficult for sperm to penetrate and fertilize an egg.
According to WHO (World Health Organization), normal sperm should have an oval head sized about 4-5μm in length and 2.5-3.5μm in width. The acrosome, which acts as a cap and helps the spermatozoa penetrate the oocyte, covers 40-70% of the sperm head. The midpiece of the sperm should be about one and a half times the length of the head, and less than 1μm in width. This leads into the tail, which should be approximately 45μm in length, and relatively straight.
Morphology abnormalities include:
- Vacuoles (nuclear concavity) in the head of the sperm that take up more than 20%
- Shape defects such as: tapered, pyriform, round, amorphous, large and small
- A cytoplasmic droplet on the midpiece that is more than half the size of a normal head
- Tail bent at an angle greater than 90°
- Tail defects such as: short, long, coiled, or multiple tails
- Multiple heads
The figure below compares the shape of a normal sperm with common abnormalities.
Does Abnormal Morphology = Male Infertility?
No. Sperm morphology alone does not determine whether or not a man can father a child. In fact, a study done by Kovac et. al in 2016 found that 29.2% of men with 0% morphology were able to conceive naturally, compared to 55.6% of men in the control group with normal morphology (≥4%).
Abnormal morphology may indicate challenges when it comes to natural conception, but does not mean natural conception is impossible.
What Causes Poor Morphology?
There are many factors that can impair male fertility:
- DNA abnormalities: If the DNA does not condense properly due to missing or added chromosomes, the shape of the head may be abnormal (not all abnormal sperm contain chromosomal defects)
- Genetic trait
- Chemical exposure
- Increased testicular temperature
- Smoking
- Alcohol use
- Caffeine
- Certain medications
- Chemotherapy drugs
- Radiation treatments
- Testosterone injection
- Harmful nutrient supplements
- Supplements containing DHEA or “andro”
Solutions For Poor Sperm Morphology
Since many of the factors that can impair male fertility are fixable, sperm morphology can be improved without medications. Studies show there is a relationship between sperm shape and caffeine, alcohol and tobacco use. So while trying to conceive, staying away from these may be beneficial to the functionality of sperm. Obesity has also been associated with problems with sperm production, so it is important to maintain a healthy diet and normal body weight while trying to conceive.
Vitamins may also benefit sperm and improve morphology. Some vitamins proven to be beneficial to sperm morphology include: Vitamins C & E, Coenzyme Q10, and Lycopene.
Since the ultimate goal of sperm is to fertilize an egg, the best way to achieve that goal is to be in the best shape possible. It is important to remember the life cycle of sperm is fairly long. Therefore, it may take up to 3 months for morphology scores to improve after lifestyle changes have been made.
Male Factor Infertility Treatments
When the sperm morphology score falls below 4%, your physician will discuss treatment options with you. As discussed above, achieving pregnancy on your own is still possible with low morphology scores, but the chance of conception may be increased by pursuing fertility treatments.
The two main treatment options for male factor infertility are intrauterine insemination (IUI) and in vitro fertilization with intracytoplasmic sperm injection (IVF-ICSI). IUI involves the process of placing sperm directly into the woman’s uterus using a small catheter at the time of her monthly ovulation. In order for pregnancy to occur with IUI, the sperm must still penetrate the egg on its own. IVF-ICSI involves harvesting eggs from a woman’s ovaries and fertilizing these eggs with sperm in the embryology lab. ICSI is a procedure performed as part of IVF in which a single sperm is isolated and injected directly into an egg. ICSI overcomes most functional problems with the sperm, as the sperm is no long required to penetrate the egg on its own.
There is no established threshold value for a morphology score which predicts successful conception, whether with natural conception, IUI, or IVF-ICSI. Your physician will use other factors in addition to a morphology score, such as the age of the female partner, and the status of the other sperm parameters when discussing or predicting the likelihood of conception. For example, if sperm concentration and sperm motility are normal or high, it may be reasonable to consider IUI before IVF-ICSI in a young woman with no other source of infertility. At Carolina Conceptions, we often advise IVF-ICSI over IUI once the morphology score falls to less than 2%. In addition, for all couples going through the IVF process (regardless of infertility diagnosis) we recommend ICSI when the morphology score is 4% or less to improve fertilization rates and pregnancy rates.
For women under 35 years of age, IUI offers a 15-20% chance of pregnancy per cycle, and IVF-ICSI offers a 60-70% chance of pregnancy.