1.Semen analysis
At least 2 times with 2-3 months interval, semen testing was done according to WHO standards. Azoospermia is defined as the absence of spermatozoa found in multiple smears by placing small drops under 400x microscope carefully after centrifugation of the specimen after semen liquefaction. Ejaculatory duct obstruction or congenital bilateral vas deferens (CBAVD) is first considered in cases with semen volume less than 1.5 ml, acidic PH, and low fructose. When the semen volume is low, post-ejaculatory urine examination should also be performed to exclude retrograde ejaculation. If no sperm or non-maturing spermatogenic cells can be found in the semen smear, complete obstruction of the proximal or distal part of the seminal tract is considered.
2. Medical history inquiry
History of the following medical conditions may easily lead to obstruction: hematospermia, pain after ejaculation, previous or current urethritis, prostatitis urinary tract obstruction or irritation; previous scrotal enlargement, pain, surgery; previous inguinal hematoma, trauma; chronic lung infection.
3.Physical examination
Physical signs of obstructive azoospermia.
A. At least one testicle volume greater than 12 ml or more (smaller testicle volume in obstructive azoospermia with partial spermatogenic failure)
B. Epididymis is large and hard
C. Epididymal or vas deferens nodules
D. Absence or partial atresia of the vas deferens
E. inflammatory body of the urethra
F. Abnormal prostate gland
4.Ultrasound examination
Scrotal ultrasound is helpful for the detection of some obstruction signs (e.g. dilated testicular network, epididymal cyst, vas deferens), and it can exclude testicular dysplasia. Patients with low semen volume or suspected distal obstruction must be examined by urethral ultrasound.
5.Inhibin B
Inhibin B is produced by the cells of the reproductive system and is closely related to fertility, and has endocrine, paracrine and autocrine regulatory effects on reproductive function. The serum inhibin B level in men with sperm production obstruction is significantly lower than that in men with normal sperm production function. The inhibin B level reflects the function of the entire testicular tissue, which is a direct product of the vas deferens, and can be used to distinguish patients with obstructive and non-obstructive azoospermia.
6. α-Glucosidase
Alpha-glucosidase in semen is mainly secreted by the epithelial cells of the epididymis. It is a specific enzyme and marker enzyme of the epididymis, which can catalyze the breakdown of the sugar component of proteins or oligosaccharides to provide suitable energy for sperm maturation, and the enzyme can be used as a functional indicator of the epididymis. When the vas deferens is ligated, the activity of this enzyme is significantly reduced. The measurement of this enzyme has some significance in identifying azoospermia caused by vas deferens obstruction and testicular spermatogenesis disorder.
7. Six endocrine items
Male infertility patients are more likely to have endocrine abnormalities than normal normal people. It is usually necessary to test follicle stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL), estradiol (E2), total testosterone (TT) and free testosterone (FT), i.e. sex hormone six. In patients with azoospermia and extreme oligo-teratogenic sperm syndrome (OAT), endocrine tests are of greater clinical significance to distinguish obstructive or non-obstructive factors, and sex hormone levels are mostly normal in patients with obstructive azoospermia. Combined testing of serum inhibin B and FSH can improve the accuracy of spermatogenic function assessment in patients.
8.Invasive diagnosis
Testicular biopsy, scrotal exploration, and distal sperm tract evaluation can be used in patients with azoospermia suspected of having acquired factors causing sperm tract obstruction, but exploration and recanalization surgery should be performed simultaneously.