Sperm morphology refers to the size, shape, and structure of sperm cells. When a large proportion of sperm have abnormal forms, the condition is called teratozoospermia. Morphology is one of the three key parameters in a standard semen analysis, along with count and motility.
What Is Normal?
Using strict Kruger criteria, only sperm that meet very precise structural standards are considered normal. A normal result is typically 4% or more normally shaped sperm. Values below this indicate teratozoospermia. It is completely normal for the majority of sperm in any ejaculate to show some structural defects – this is part of human biology.
Types of Morphological Defects
- Head defects: large, small, tapered, or round heads; abnormal acrosomes
- Midpiece defects: bent or thickened midpieces, cytoplasmic droplets
- Tail defects: coiled, short, or double tails
- Globozoospermia: a rare severe form where sperm have round heads lacking an acrosome, preventing fertilisation without ICSI
Causes
- Genetic factors affecting spermatogenesis
- Varicocele
- Infections and inflammation of the reproductive tract
- Oxidative stress from smoking, alcohol, obesity, and poor diet
- Heat exposure, radiation, and environmental toxins
- Advanced paternal age
- Chronic illness and certain medications
Does Abnormal Morphology Always Cause Infertility?
Not necessarily. Many men with low morphology scores father children naturally, and morphology alone is rarely a reliable predictor of fertility. However, when combined with other abnormalities or persistent failure to conceive, it becomes clinically significant and warrants treatment consideration.
Treatment Approach
- Lifestyle changes: Smoking cessation, weight optimisation, avoiding heat, balanced diet rich in antioxidants.
- Antioxidant supplementation: Vitamin C, vitamin E, CoQ10, zinc, and selenium may improve sperm quality over 3–6 months.
- Treat underlying causes: Varicocele repair, infection management, and hormonal therapy when appropriate.
- Advanced sperm selection: IMSI (high-magnification sperm selection) or PICSI may help select morphologically better sperm during ICSI.
- ICSI: When morphology is very poor, ICSI bypasses the natural fertilisation barriers and remains the most effective option.
A diagnosis of teratozoospermia can be worrying, but it rarely means that fatherhood is out of reach. A thorough evaluation helps place the finding in context and identify the best path to pregnancy.