Thanks for the query,
Asthenospermia refers to motility defects in sperm.
This could be due to problem in sperm production., malnutrition
, testicular injury
, overheating,genetic, smoking.
In your husband's case best treatment option would be:
A transrectal ultrasound
(TRUS) in order to confirm the presence or absence of ejaculatory duct
Presence of a cyst or calcification at the ejaculatory duct,
The size of the seminal vesicles will be measured to determine whether there is any significant
Following which last resort would be ICSI, TESA, PESA.
Wish you good luck.