How does abnormal morphology sperm affect fertility and what are the treatment options?

Abnormal Sperm Morphology: Impact on Fertility and Treatment Options

Abnormal sperm morphology (teratozoospermia) alone should not preclude couples from attempting natural conception before pursuing assisted reproductive technologies, but it can significantly impact fertility and may require specialized treatment depending on severity. 1

Understanding Sperm Morphology and Its Impact

• Sperm morphology refers to the shape and structure of sperm, with the World Health Organization (WHO) establishing a lower reference limit of 4.0% morphologically normal forms (range 3.9-4.0%) as part of standard semen analysis 2, 3
• Abnormal sperm morphology is associated with higher rates of testicular cancer, and men with azoospermia have higher rates of cancer in general compared to fertile men 2
• Teratozoospermia can range from mild (where a small percentage of sperm have abnormal morphology) to severe monomorphic forms (where >85% of sperm show the same specific abnormality) 4, 5
• Specific severe forms include globozoospermia (round-headed sperm), macrozoospermia (enlarged sperm heads), and acephalic spermatozoa (headless sperm), which often have genetic causes 4, 5

Evaluation of Abnormal Sperm Morphology

• Initial evaluation should include a comprehensive semen analysis using WHO criteria, with morphology assessment being an essential component 2, 3
• For men with abnormal semen parameters, including teratozoospermia, a full evaluation by a urologist or specialist in male reproduction is recommended 2
• When multiple semen abnormalities are present (not just isolated morphology issues), the clinical significance is greater 2
• Genetic testing should be considered in cases of:
  • Severe oligozoospermia (<5 million/mL) with elevated FSH or testicular atrophy 2
  • Monomorphic teratozoospermia affecting >85% of sperm 4, 5
  • Azoospermia 2

Factors Affecting Sperm Morphology

• Lifestyle factors that may negatively impact sperm morphology include:
  • Smoking (low-quality evidence suggests a small impact on morphology) 2
  • Diet high in fats and low in fruits and vegetables 2
  • Use of anabolic steroids 2
  • Obesity (though evidence is conflicting) 2
• Environmental and occupational exposures may also affect sperm parameters, though data on specific factors are limited 2

Treatment Options

1. Lifestyle Modifications:

   • Smoking cessation is recommended for men trying to conceive 2
   • Diet lower in fats and higher in fruits and vegetables may be beneficial 2
   • Discontinuation of anabolic steroids if used 2

2. Medical Interventions:

   • There are insufficient data to recommend supplemental antioxidant therapies for men with abnormal semen parameters 2
   • There are insufficient data to recommend herbal therapies for men with abnormal semen parameters 2

3. Assisted Reproductive Technologies (ART):

   • Natural conception attempts may be reasonable before pursuing ART for men with isolated teratozoospermia 1
   • Intrauterine insemination (IUI) may be considered for mild to moderate cases 6
   • In vitro fertilization (IVF) with or without intracytoplasmic sperm injection (ICSI) may be necessary for severe cases 6, 7
   • ICSI is particularly important for specific sperm defects like globozoospermia, macrozoospermia, and acephalic sperm syndrome 5, 7

4. Treatment of Underlying Conditions:

   • If varicocele is present and palpable, varicocelectomy may improve semen parameters when there is evidence of abnormal semen parameters 2, 8
   • For men with varicocele and azoospermia, varicocelectomy may lead to the appearance of sperm in the ejaculate, especially in cases of hypospermatogenesis 8

Important Considerations and Caveats

• Sperm morphology assessment has poor sensitivity and specificity in diagnosing infertility except in cases of specific genetic sperm defects 6
• Transmission electron microscopy (TEM) provides more detailed assessment of sperm ultrastructure than standard light microscopy in research settings 7
• Oxidative stress is one of the most important causes of altered sperm morphology and function 7
• Sperm DNA fragmentation may adversely affect natural fertility and ART outcomes, including increased miscarriage rates 2
• Advanced paternal age (≥40) increases risk of adverse health outcomes for offspring, including genetic mutations and certain medical conditions 2

Follow-up and Monitoring

• If abnormalities are detected in the initial semen analysis, a second confirmatory analysis should be performed at least one month after the first 3
• For men undergoing varicocelectomy, improvements in semen parameters typically take 3-6 months (two spermatogenic cycles) 8
• Genetic counseling should be considered for couples with identified genetic causes of teratozoospermia before proceeding with ART 2, 4