Oligospermia is a profoundly disturbing diagnosis for a man. It needs careful evaluation before a definitive diagnosis is made, and before appropriate treatment can be decided upon.
Image shows human sperm and cell bodies photomicrograph viewed under a 100x objective.
Semen analysis is the primary technique to test for male fertility, and is often the point of referral. Two ejaculated samples are taken by the male, either by masturbation, or if there are objections to this practice, in a non-spermicidal condom. The samples are best taken six weeks apart if the first is in any way abnormal. Three days of sexual abstinence will ensure the sample is representative of the true semen constitution.
Semen analysis may help detect the following:
1. Abnormalities in sperm count
- Azoospermia - the absence of sperm in semen
- Oligozoospermia - the presence of less than 15 million sperm/ml
2. Abnormalities of sperm function and motility (asthenospermia)
Sperm with a progressive forward motility of less than 25 microns/second must constitute at least 50 percent of the sperm sample. When sperm in the sample are persistently immotile or poorly motile, fertilization is unlikely to occur as they cannot pass the cervical mucus to reach the uterine cavity.
3. Abnormalities of sperm morphology (teratospermia)
Sperm are classified morphologically using the WHO classification or Kruger’s strict criteria, and this provides additional information to the other parameters in determining semen quality.
4. Home fertility-testing kits
Many men feel it a slur on their virility to have their fertility tested, though both need not be related. For this reason many men prefer to test their semen at home instead. Whilst, these tests may accurately provide the sperm count but fail to follow recent guidelines, which define oligospermia as less than 15 million sperm/ml.
Secondly, they check the sperm number but not the morphology or motility, which are equally important in determining the success of fertilization. In this way they may provide false reassurance, thereby needlessly delaying the patient’s visit for the necessary treatment to aid conception. Conversely, the testing kit may give the impression that the sperm count is low when it is within normal limits.
Men with oligospermia must have a careful history taken, including:
- Frequency of intercourse
- Erectile dysfunction
- Testicular or scrotal surgery
- Urinary tract symptoms
- Past illnesses
- Smoking, alcohol or drug abuse
- Past and current medications which may decrease the sperm count or motility
Physical examination includes looking for signs of hypogonadism, hypoandrogenism, any systemic illness, and any structural abnormalities of the external sexual organs, including the presence of a varicocele or cryptorchidism.
Imaging tests such as scrotal ultrasonography may be required to exclude a testicular tumor or a varicocele.
The prostate and seminal vesicles may require visualization using transrectal ultrasonography, as when there is, for instance, a very low semen volume.
Hormone testing may be necessary, including testing for serum follicle stimulating hormone (FSH) levels as an indicator of poor sperm production. High FSH levels with low testosterone indicate testicular unresponsiveness, but low FSH and testosterone indicate gonadotropin deficiency. FSH may be normal in the case of some mutations which cause late maturation arrest.
This evaluation will reveal the difference between obstructive and non-obstructive azoospermia by providing data on testis size and consistency, other signs of hypogonadism, and gonadotropin levels. Approximately seven out of ten men with infertility will be offered an etiological diagnosis at this stage.
When there is no clinical or laboratory evidence of testicular failure, genetic testing is not indicated. Similarly, if there is any clear etiological factor identified in the history and examination, it is not required, or if the man has secondary infertility.
Genetic testing is indicated in men who have azoospermia or severe oligospermia, with suspected congenital obstruction. It is also suitable for those with primary or incomplete testicular failure, and congenital hypogonadotropic hypogonadism, as well as those with normal FSH and testicular volume with non-obstructive azoospermia. These tests may include:
Translocations or inversions are found in approximately 6 percent of infertile men. They are also found in cases of aneuploidy such as Klinefelter’s syndrome or 46XX with translocation of the SRY-containing distal tip of the short arm of the Y chromosome to the corresponding region of the X chromosome.
X-linked genes such as Xq11.2-12 coding for the androgen receptor may be abnormal, resulting in various degrees of androgen insensitivity and leading to azoospermia with a 46XY chromosomal complement.
- Y chromosome microdeletions (YCMD)
YCMD are usually on the Yq or long Y arm, and lead to the loss of the azoospermic factor (AZF) regions involved in coding for spermatogenesis. In 60 percent of such men no sperm can be found in the testes. In the remaining, with AZFC microdeletions, though sperm are usually retrieved, the mutation is transmitted to the offspring via ICSI. YMCD are usually detected using PCR.
A transmembrane regulator (CFTR) gene mutations on chromosome 7q31.2 should be looked for in all men with congenital bilateral absence of the vasa deferentia (CBAVD), as up to 80 percent have two abnormal copies of this gene. Cystic fibrosis (CF) can result from over 1700 mutations, however, up to a quarter of patients with CBAVD cannot be said to have CF with certainty. Female partners must be tested for the gene before ICSI – this is because heterozygous CF alleles which could put the offspring at risk of CF or infertility.
- MLH1, MSH2 or other genes associated with maturation arrest of sperm.
Testicular micro-biopsy may be required in the last resort to distinguish between obstructive and non-obstructive azoospermia if all other clinical and laboratory parameters are normal – this will confirm the presence of sperm.
Reviewed by Afsaneh Khetrapal BSc (Hons)