9. A couple in their late 20s present to the infertility clinic with a two-year history of primary infertility. The woman, aged 25 years with a BMI of 23 kg/m2, is found to have normal genitalia with regular ovulatory cycles. The partner, aged 28 years with a BMI of 36 kg/m 2 , is noted to have gynecomastia and small testis. A semen analysis confirms azoospermia. Hormone investigations showed a low testosterone level, high sex hormone binding globulin (SHBG) and raised gonadotrophins.
Which one of the following diagnostic options represents the most likely cause for the male infertility?