Interpretation of abnormal Semen Analysis Results
It is always important to consider whether the result is spurious. Repeated tests are necessary to establish an average and to determine the variability within an individual man .
Variations in Semen Volume and Appearance
Low semen volume suggests incomplete collection, short duration of abstinence from ejaculation before the test, absence or obstruction of the seminal vesicles, or androgen deficiency. High semen volume (>8 mL) may be seen in association with oligospermia but is of little practical significance. Hemospermia is usually the result of minor bleeding from the urethra, but serious conditions, such as genital tract tumors, must be excluded. Other discoloration of the semen may indicate inflammation of accessory sex organs. The semen may be yellow with jaundice or salazopyrine administration. Defects of liquefaction and viscosity are relatively common and presumably result from malfunction of the accessory sex organs. Although these may cause problems with semen analysis and preparation of sperm for assisted reproductive technology (ART), they are probably of little relevance to fertility. Sperm agglutination is common with sperm autoimmunity but can also occur for other reasons.
The total absence of sperm from the semen needs to be confirmed in repeated tests with vigorous centrifugation of the semen and careful examination of the pellet. Rarely, an illness or difficulty with collection will cause transient azoospermia; however, this can also occur for unexplained reasons. With severe spermatogenic disorders and some obstructions, sperm may be present in the semen intermittently. If any live sperm can be found, these can be cryopreserved for intracytoplasmic sperm injection (ICSI).
Oligospermia – low sperm count
Sperm concentrations of less than 15 million/mL or preferably total number (concentration X volume) less than 39 million are classified as oligospermic. This figure represents the 5th percentile derived from analysis of semen analyses preformed using WHO methods in about 1900 healthy volunteers whose partners had a time-to-pregnancy of ≤12 months and is used in the 5th edition of the WHO semen analysis manual . There is a correlation between sperm concentration and other aspects of semen quality. Both motility and morphology are usually poor with oligospermia.
Asthenospermia is defined as less than 40% sperm motility or less than 32% with rapid progressive motility. Spurious asthenospermia caused by exposure of sperm to rubber (particularly condoms), spermicides, extremes of temperature, or long delays between collection and examination, should be excluded. Low sperm motility is a frequent accompaniment of oligospermia, and is often also associated with a mixed picture of morphologic defects suggesting defective spermiogenesis.
Specific ultrastructural defects of the sperm can be evaluated by electron microscopy when there is zero sperm motility or extreme asthenospermia (less than 5% motile sperm). Absent dynein arms, other axonemal defects, mitochondrial abnormalities, disorganized fibrous sheath or outer dense fibers, or normal ultrastructure may be found. Standard semen analyses usually show normal sperm concentrations and morphology but there may be tail abnormalities: short, straight, or thick tails, or midpiece defects. Viability tests help to distinguish this group of patients from those with necrospermia. Patients with structural defects in the sperm may be able to be treated by ICSI. Asthenospermia may also be associated with sperm autoimmunity. The causes of other motility defects of moderate degree are unidentified.
It is important to distinguish necrospermia from other types of severe asthenospermia because some patients with necrospermia produce pregnancies despite the low sperm motility. Necrospermia is characterized by usually less than 20% to 30% total motility, less than 5% progressive motility, and a viability test less than 30% to 40%, indicating a high proportion of dead sperm. Other causes of severe asthenospermia such as sperm autoimmunity and collection problems must be excluded. Necrospermia may fluctuate in severity, particularly with changes in coital frequency. Characteristic of necrospermia is an improvement of sperm motility with increased frequency of ejaculation. The condition may be caused by defective storage of sperm in the tails of the epididymides or stasis in the genital tract, and it also occurs with chronic spinal cord injury and with adult polycystic kidney disease associated with cysts in the region of the ejaculatory ducts. There are ultrastructural features of degeneration in the ejaculated sperm but normal structure of late spermatids in testicular biopsies. Treatment with antibiotics may have a beneficial effect, but this is not proved. The couple should have intercourse once or twice every day for 3 to 4 days up to the time of ovulation.
Teratospermia – abnormal sperm morphology
Teratospermia is a reduced percentage (<4%) of sperm with normal morphology – higher percentage of sperm with abnormal morphology, assessed by light microscopy. It is important to distinguish mixed abnormalities of sperm morphology from those in which all or the majority of sperm show a single uniform defect, such as spherical heads with absence of the acrosomes (globospermia) and pinhead sperm. Pinhead sperm result when the centrioles from which the sperm tails develop are not correctly aligned opposite the developing acrosome. On spermiation, the sperm heads are disconnected from the tails and absorbed during epididymal transit so that there are only sperm tails in the ejaculate, the cytoplasmic droplet on the midpiece giving the pinhead appearance. Both these conditions cause sterility but are extremely rare.
In general, human spermatozoa are very variable in appearance and the microscopic assessment of sperm morphology is highly subjective and difficult to standardize between laboratories. Only a small proportion (<25%) of the motile sperm from fertile men are capable of binding the ZP in vitro, and this zona binding capacity is closely related to the morphology of the sperm head. The morphometric characteristics of the sperm that bind to the ZP may be useful as a standard for sperm morphology. Various histological assessments of morphology have been used. The simplest is to record as normal only those sperm that have no shape defects in head, midpiece or tail, regions. In the strict morphology approach, although size measurements are set, the sperm are assessed by eye and those marginally abnormal are assigned abnormal. Automated methods involving image analysis by computer have been developed that could overcome the between-laboratory variability and greatly improve the predictive value of semen analysis for natural conception.
Before the introduction of ICSI, the percentage of sperm with normal morphology assessed by strict criteria after washing the sperm and adjusting the concentration to 80 million/mL, provided one of the most useful predictors of fertilization rates with standard IVF. There was a progressive reduction in oocytes fertilized from 60% to 20% as abnormal morphology increased from less than 70% to more than 95%. Patients with high proportions of sperm with abnormal morphology are now treated by ICSI because of the risk of failure of fertilization with standard IVF. ICSI results are independent of sperm morphology.