Asthenozoospermia

Asthenozoospermia is reduced sperm motility, defined as progressive motility under 30% or total motility (progressive plus non-progressive) under 42% in a fresh ejaculate.

It is the most frequent single semen abnormality in infertile men, found alone or with low count or abnormal shape.

Most cases are acquired and treatable, but severe forms from structural flagellar defects need intracytoplasmic sperm injection.

Pathophysiology. Motility needs intact axonemal structure, adequate energy from mitochondria and a healthy epididymal environment.

Causes:

• Varicocele, with heat and oxidative stress.
• Genital tract infection and inflammation (prostatitis, epididymitis), with excess leucocytes in semen.
• Antisperm antibodies after vasectomy, trauma or infection.
• Prolonged abstinence, febrile illness, smoking, obesity, heat and gonadotoxic drugs.
• Genetic and structural flagellar defects: primary ciliary dyskinesia (dynein arm defects), dysplasia of the fibrous sheath, and mutations in genes such as DNAH1 and CATSPER.
• Partial epididymal obstruction.
• Idiopathic, in many.

Infertility with usually no symptoms. Varicocele, prostatic tenderness, epididymal thickening or small testes may be found. Chronic sinusitis, bronchiectasis and situs inversus point to primary ciliary dyskinesia. Ask about fever in the last 3 months, drugs, heat exposure and smoking.

• Two semen analyses after 2 to 7 days of abstinence, with motility graded as progressive, non-progressive and immotile, assessed within 1 hour.
• Sperm vitality testing (eosin nigrosin or hypo-osmotic swelling) when motility is under 5%. Viable but immotile sperm suggest a structural defect, and non-viable sperm suggest necrozoospermia.
• Semen culture, peroxidase staining for leucocytes (over 1 million/mL indicates leucocytospermia), and urethral swab or urine nucleic acid test for chlamydia, gonorrhoea and mycoplasma.
• Antisperm antibody test (mixed antiglobulin reaction) when there is agglutination or after vasectomy reversal.
• Hormones: FSH, LH, total testosterone, prolactin.
• Scrotal ultrasound for varicocele and epididymal abnormality.
• Electron microscopy of sperm, and genetic testing of flagellar genes, when the sample shows total or near total immotility with normal vitality. Nasal nitric oxide, ciliary studies or chest imaging if respiratory features are present.

Differential diagnosis.

• Necrozoospermia
• Oligoasthenoteratozoospermia
• Varicocele
• Genital tract infection
• Primary ciliary dyskinesia
• Antisperm antibodies
• Epididymal obstruction or ejaculatory duct obstruction

• Lifestyle: stop smoking, lose weight, limit alcohol, avoid heat exposure, and shorten abstinence to 1 to 2 days when DNA damage is suspected.
• Treat infection: doxycycline 100 mg orally twice daily for 14 days for chlamydia and mycoplasma, ciprofloxacin 500 mg orally twice daily for 14 days (reduced when eGFR is under 50) or longer for prostatitis, and treat partners. Antibiotics help when leucocytospermia or pathogens are found, and not otherwise.
• Varicocelectomy for a palpable varicocele with abnormal semen and couple infertility.
• Antioxidants have inconsistent evidence. If used, coenzyme Q10 200 to 300 mg daily or L-carnitine 2 g daily for 3 to 6 months.
• Antisperm antibodies: intracytoplasmic sperm injection is preferred, since corticosteroids carry risk and have limited benefit.
• Assisted reproduction:
  • Post-wash total motile count over about 5 million: intrauterine insemination.
  • Severe asthenozoospermia, or count under about 5 million: in vitro fertilisation with intracytoplasmic sperm injection.
  • Total immotility with viable sperm: select live sperm by hypo-osmotic swelling or laser, and inject. Testicular sperm often have better motility than ejaculated sperm and are used in severe cases or high DNA fragmentation.
• Primary ciliary dyskinesia: respiratory care and sinus management by a specialist, with genetic counselling.

Monitoring. Repeat semen analysis at 3 months after any intervention, which covers one cycle of sperm production. Review the couple at 6 months.

Referral and escalation. Refer to urology or andrology and a fertility unit for motility under 10%, abnormal examination or failure of 6 months of treatment. Urgent referral for fever with perineal pain, or a testicular mass.