Azoospermia can be initially judged as azoospermia after multiple routine semen examinations have not found sperm and retrograde ejaculation factors have been excluded. A large percentage of these cases are obstructive azoospermia. Obstructive azoospermia has a good chance of being cured and can lead to conception through natural sexual intercourse, so it is important to explain this clearly.
Obstructive azoospermia is a condition in which no sperm or spermatogenic cells are seen in the semen or urine after ejaculation due to bilateral obstruction of the seminal tract. There are various reasons for obstruction, and when explaining to patients I often give the example that the testes are like a factory for sperm production, and the “highway” from the testes to the completion of ejaculation is the seminal tract. Of course, if the road is opened through certain techniques, or even “secretly”, as long as the sperm can be discharged, there is a possibility of natural conception.
According to the different parts of the “road” obstruction can be distinguished as
1. Intra-testicular obstruction.
It accounts for 15% of obstructive azoospermia, with more acquired than congenital factors (causing dysfunction between the testicular network and the testicular output duct), and acquired factors such as inflammatory and traumatic obstruction, often accompanied by obstruction of the epididymis and vas deferens
2.Epididymal obstruction.
Epididymal obstruction is the most common cause of obstructive azoospermia, accounting for 30-67% of azoospermia in which FSH is less than two times the high limit of normal value.
Congenital epididymal obstruction is often associated with congenital bilateral vas deferens (CBAVD). Congenital epididymal obstruction also includes Young’s syndrome, where the obstruction is mainly caused by fibrosis in the lumen of the proximal epididymal duct.
Acquired epididymal obstruction is mainly due to acute epididymitis (gonorrhoea) and subclinical forms of epididymitis (e.g., chlamydia). Acute and slow trauma can also lead to epididymal injury.
Surgical obstruction, such as epididymal cyst removal and surgical operation on the distal epididymis.
3.Vas deferens obstruction
The most common cause of vas deferens obstruction is vasectomy due to birth control. About 2-6% of patients require vasectomy reanastomosis, and 5-10% of vasectomy is found to cause epididymal obstruction due to rupture of the epididymal duct, which often requires epididymal vasectomy.
Vas deferens obstruction can also occur after hernia repair.
4.Ejaculatory duct obstruction.
Ejaculatory duct obstruction accounts for 1-3% of obstructive azoospermia, and the two main causes are cystic and inflammatory. Cystic is usually congenital (Miller’s duct or urethral genital sinus cyst, ejaculatory duct cyst), in Miller’s duct cyst the ejaculatory duct is displaced laterally due to compression by the cyst, the urethral genital sinus cyst communicates with one or both ejaculatory ducts, congenital or acquired complete obstruction of the ejaculatory duct is often accompanied by low semen volume, fructose deficiency and PH acidity, and the seminal vesicles are usually distended (anterior and posterior diameters greater than 15 mm).
5.Functional obstruction of the distal part of the seminal tract
This may be due to local neurogenic factors, due to smooth muscle weakness of the vas deferens or hypertonicity of the ejaculatory ducts, abnormalities that are associated with abnormal urinary flow dynamics. Although they have been observed in patients with juvenile diabetes mellitus or polycystic kidneys, there is no pathological basis for this, and sperm analysis results in azoospermia, weak sperm, and severe oligospermia.
How to diagnose obstructive azoospermia
1. Semen analysis, at least 2 times with an interval of 2-3 months, for semen testing according to WHO standards. Azoospermia is defined as the absence of sperm found in multiple smears by placing a small drop under a 400x microscope after centrifugation (600rpm, 15M) of the specimen after semen liquefaction.
2.Pursue the medical history
3. Pay great attention to physical examination. Vasectomy defects are often missed!
Signs of obstructive azoospermia: at least one testicle volume greater than 15 ml or more (smaller testicle volume in obstructive azoospermia with partial failure of spermatogenesis); large and hard epididymis; epididymal or vas deferens nodules; vas deferens absence or partial atresia; signs of urethritis; prostate abnormalities.
4. To understand the level of sex hormones. Mainly to rule out testicular azoospermia (such as spermatogenic block)
5.Reproductive ultrasonography. For patients with low semen volume or suspected distal obstruction, transrectal ultrasonography must be performed to determine the development of seminal vesicles.
6.Testicular biopsy. Testicular biopsy can rule out testicular failure, and when surgical revascularization cannot be performed or fails, TESE can be performed at the same time to obtain sperm for freezing for the next cycle of ICSI
7. Vasectomy, which has been done less frequently, unless there is an indication of suspected obstruction of the pelvic segment of the vas deferens, most doctors prefer intraoperative lavage or melanoma test.
Treatment of obstructive azoospermia
1. Intra-testicular obstruction
Because surgical reconstruction at this level is not possible, TESE or fine needle aspiration of testicular sperm is commonly used. The sperm obtained should be used immediately for ICSI treatment or cryopreservation, and TESE or fine needle aspiration is suitable for almost all obstructive azoospermia.
2.Epididymal obstruction
CBAVD commonly uses microsurgical epididymal sperm aspiration (MESA) to obtain sperm, and the obtained sperm is usually used for ICSI treatment. Generally, the sperm obtained from one MESA is sufficient for multiple ICSI cycles. Microsurgical end-to-end or end-to-side epididymal vasovasostomy is feasible for azoospermia caused by acquired acquired epididymal obstruction.
Surgical reconstruction can be unilateral or bilateral, with generally higher patency and pregnancy rates with bilateral reconstruction. It is essential to check for patency downstream of the epididymis prior to surgical procedures, with a follow-up period of 3-18 months after surgery. Also prior to all microsurgical procedures and in all patients who cannot have reconstructive surgery, epididymal sperm should be aspirated and cryopreserved for ICSI treatment (after failed reconstruction).
Microsurgical recanalization rates range from 60-87% and cumulative pregnancy rates range from 10-43%. The success rate of recanalization is related to preoperative conditions and intraoperative findings, and is lower in patients with concomitant testicular pathological abnormalities, absence of sperm in the epididymal tubular fluid, and extensive fibrosis of the epididymis
The finding of live or dead sperm at different anatomical levels of the epididymis does not seem to be related to recanalization rates, but recanalization rates and pregnancy rates are significantly lower in epididymis with movable epididymal heads and bodies. In the natural cycle, sperm must pass through part of the epididymis to mature before they can unite with the egg for fertilization. The results are worse in those with ultrasound abnormalities of the seminal vesicles or prostate.
In terms of birth rate, epididymal obstruction due to vasectomy is superior to epididymal vasectomy with higher success rate and more economical than MESA for ICSI.
3.Proximal vas deferens obstruction
Proximal obstruction after vasectomy requires microsurgical vasectomy for recanalization, and vasectomy-vasectomy anastomosis can only be used for a small number of patients. The existence of secondary epididymal obstruction can be confirmed when no spermatozoa are detected in the intraoperative vasectomy fluid, especially when there is toothpaste-like “toothpaste” mucus in the proximal vasectomy fluid. Vasectomy with epididymal anastomosis should be performed.
4.Distal vas deferens obstruction
Extensive bilateral loss of vas deferens due to hernia or testicular descending and fixing surgery during childhood is usually not reconstructable. In these cases, sperm should be extracted from the proximal vas deferens] or TESE or MESA should be used for ICSI treatment. Extensive unilateral vasectomy with ipsilateral testicular atrophy may be considered for vasovasovaginal anastomosis or vasovaginal epididymal anastomosis with the contralateral side.
In the past decade, the vas deferens was fixed in the epididymis or proximal vas deferens as a surgical method, but with little success, the procedure is no longer advocated.
5.Ejaculatory duct obstruction
Treatment of ejaculatory duct obstruction depends on the etiology. Transurethral resection of the ejaculatory duct (TURED) should be performed, which may remove part of the spermatic port.