Along general lines, azoospermia may be due to a lack of sperm production on the part of the testicles (secretory azoospermia) or to an obstruction of the long ducts through which the sperm travel until they are expelled by the urethra during ejaculation (excretory or obstructive azoospermia).
The most frequent causes of secretory azoospermia are:
- Problems in the development or descent of the testicles (absence or poor development of the testicle, cryptorchidism, etc)
- Testicle problems (inflammations, trauma)
- Radiotherapy and chemotherapy
- Hormonal problems
- Genetic disorders
The most frequent causes of obstructive azoospermia are:
- Problems (inflammations, trauma) in the testicles, epididymis, deferens, ejaculatory ducts or prostate.
- Congenital and/or genetic irregularities which lead to the absence or anomaly of the seminal vesicle (e.g. congenital bilateral absence of deferens ducts due to mutations of the gene in cystic fibrosis).
Diagram of masculine genital apparatus
The first study to be undertaken in the event of azoospermia is the determination of the FSH hormone levels produced in the brain (the hypophysis) and responsible for the production of sperm in the testicle. If this is very high it indicates the absence of or reduction in the sperm stem cells (spermatogonia).
In order to attempt to determine whether the azoospermia is secretory or obstructive, a biopsy of the testicle may be indicated which consists in obtaining a small fragment of each testicle under local anaesthetic and on an outpatient basis. This methodology provides confirmation of diagnosis if the testicle produces sperm (obstructive azoospermia) or not (secretory azoospermia).
Secretory azoospermia
When the testicle does not produce sperm it may be due to genetic disorders, and therefore a karyotype should be undertaken together with a specific chromosome study. This is where certain genes which determine the production of sperm are to be found.
In approximately 50% of secretory azoospermia cases it is possible to find some sperm in the testicle by means of a biopsy and this can then be used for in vitro fertilisation techniques (intracytoplasmic sperm injection).
Given that apart from forming the sperm, the testicles also produce testosterone or the male hormone which influences a large number of functions, where there are significant disorders of the testicles it may be that the production of testosterone will be affected. In these cases it is essential to take this hormone for the rest of the patient’s life.
Obstructive Azoospermia
Obstructive azoospermia may be diagnosed during the physical examination of the patient in those cases where, due to a congenital malformation, the vas deferens has not developed. In almost 100% of cases this anomaly is associated with gene mutations in cystic fibrosis and therefore a genetic study should be undertaken for all patients who wish to proceed with the intracytoplasmic sperm injection given that they present the normal number of sperm in the testicle. If gene mutations (CFTR) are detected, the same study must be undertaken on the partner. If they are both carriers of the cystic fibrosis gene it is advisable to undertake a pre-implantational genetic study of the embryos obtained in the ICSI process for the purposes of transferring to the uterus those that do not present the same problem as the parents.
When there is an obstruction in the first section of the seminal duct (epididymis) it is possible, using microsurgical techniques, to join the tubule of the healthy pre-obstructive epididymis and the vas deferens (epididymovastostomy). When the obstruction is at the level of the vas deferens, micro-surgical techniques can also join the healthy extremities in order to recover the permeability of the duct (vasovasostomy). When the obstruction is at the level of the ejaculatory ducts, an unblocking surgery may be performed, using endoscopic techniques through the urethra (transurethral resection of the ejaculatory ducts).
When, for whatever reasons, the couple do not wish or are not able to undertake these techniques (absence of part of the seminal duct) or they have failed, it is possible to obtain sperm (surgical sperm recovery) from the testicle or the seminal duct for use in the Intracytoplasmic Sperm Injection (ICSI) procedure.