A male with azoospermia. On examination size of testis is normal. FSH and testosterone levels are within normal limits. Most probable cause is:

Normal levels of FSH with azoospermia suggests obstructive lesions in the vas or epididymis. High FSH and LH may indicate primary gonadal failure-testicular Dysfunction. Low level of FSH and LH suggest hypogonadotropic hypogonadism. Shaw's Textbook of Gynaecology 16th edition page no 244