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Limitations of semen analysis as a test of male fertility and anticipated needs from newer tests

2014; Elsevier BV; Volume: 102; Issue: 6 Linguagem: Inglês

10.1016/j.fertnstert.2014.10.021

1556-5653

Christina Wang, Ronald S. Swerdloff,

Genetic and Clinical Aspects of Sex Determination and Chromosomal Abnormalities

Semen analysis is the first step to identify male factor infertility. Standardized methods of semen analysis are available allowing accurate assessment of sperm quality and comparison among laboratories. Population-based reference ranges are available for standard semen and sperm parameters. Sperm numbers and morphology are associated with time to natural pregnancy, whereas sperm motility may be less predictive. Routine semen analysis does not measure the fertilizing potential of spermatozoa and the complex changes that occur in the female reproductive tract before fertilization. Whether assisted reproduction technology (ART) is required depends not only on male factors but female fecundity. Newer tests should predict the success of fertilization in vitro and the outcome of the progeny. Semen analysis is the first step to identify male factor infertility. Standardized methods of semen analysis are available allowing accurate assessment of sperm quality and comparison among laboratories. Population-based reference ranges are available for standard semen and sperm parameters. Sperm numbers and morphology are associated with time to natural pregnancy, whereas sperm motility may be less predictive. Routine semen analysis does not measure the fertilizing potential of spermatozoa and the complex changes that occur in the female reproductive tract before fertilization. Whether assisted reproduction technology (ART) is required depends not only on male factors but female fecundity. Newer tests should predict the success of fertilization in vitro and the outcome of the progeny. Discuss: You can discuss this article with its authors and with other ASRM members at http://fertstertforum.com/wangc-semen-analysis-test-male-fertility/ Discuss: You can discuss this article with its authors and with other ASRM members at http://fertstertforum.com/wangc-semen-analysis-test-male-fertility/ Semen analysis is the cornerstone for the assessment of the male partner in a subfertile couple. Compared with many other tests used in the assessment of the infertile couple, semen analysis has been standardized throughout the world. This was made possible through the efforts of the World Health Organization (WHO) since the 1970s by producing, editing, updating, and disseminating a semen analysis manual (1World Health OrganizationWorld Health Organization laboratory manual for the examination and processing of human semen.5th ed. World Health Organization, Geneva, Switzerland2010Google Scholar). The manual provides step by step methods on how to perform a routine semen analysis, guidance on establishing internal and external quality control for these measures, and recommendations on more commonly used tests to assess sperm function. The goal of the manual is to improve the standards of semen analysis and to ensure that the semen and sperm parameters assessed in one laboratory using this manual will be the same as the analysis done in another laboratory using the same manual. International and national societies of andrology, reproductive medicine, human reproduction, and pathology contributed by providing hands on training to ensure that the technologists are using these standardized methods to assess semen and sperm quality. This allows comparative studies and pooling of data from across the globe for epidemiology studies to assess semen quality (2Carlsen E. Giwercman A. Keiding N. Skakkebaek N.E. Evidence for decreasing quality of semen during past 50 years.BMJ. 1992; 305: 609-613Crossref PubMed Scopus (2212) Google Scholar, 3Swan S.H. Brazil C. Drobnis E.Z. Liu F. Kruse R.L. Hatch M. et al.Geographic differences in semen quality of fertile U.S. males.Environ Health Perspect. 2003; 111: 414-420Crossref PubMed Scopus (246) Google Scholar) and to develop reference ranges for semen and sperm parameters (4Cooper T.G. Noonan E. Von E.S. Auger J. Baker H.W. Behre H.M. et al.World Health Organization reference values for human semen characteristics.Hum Reprod Update. 2010; 16: 231-245Crossref PubMed Scopus (1707) Google Scholar). Semen analysis should be performed in laboratories with experienced technologists who have been trained in these standardized methods for routine clinical examination of semen. Despite our ability to assess sperm quality through a semen analysis methodology harmonized across laboratories, the use of these parameters cannot precisely and accurately predict the fertility of a man presenting to a clinician. This is because there are many factors in addition to sperm and semen quality that contribute to the ability of spermatozoa to fertilize an oocyte. To reach and fertilize the oocyte ejaculated spermatozoa have to traverse the female reproductive tract, hyperactivate and undergo acrosome reaction at the correct time and site, penetrate the cumulus and zona pellucida (ZP), and ultimately fuse with and fertilize the oocyte. The assessment of some of these changes in the spermatozoa will be discussed in other articles in this series. In addition to sperm function, female factors are extremely important to ensure optimization of the condition of the oocyte to allow for fertilization (5te Velde E.R. Eijkemans R. Habbema H.D. Variation in couple fecundity and time to pregnancy, an essential concept in human reproduction.Lancet. 2000; 355: 1928-1929Abstract Full Text Full Text PDF PubMed Scopus (93) Google Scholar). Many studies have been criticized for the selection of subjects and methods used to develop reference ranges for semen and sperm quality, in particular the thresholds defining male factor subfertility using sperm concentration, motility, and morphology, the three classic sperm parameters measured by all laboratories. The WHO initially adopted a sperm concentration of 50% motile, and normal sperm morphology of >50% as thresholds below which subfertility may be present. This was based on studies done in the 1950s by Macleod and colleagues (6Macleod J. Semen quality in 1000 men of known fertility and in 800 cases of infertile marriage.Fertil Steril. 1951; 2: 115-139Abstract Full Text PDF PubMed Google Scholar, 7Macleod J. Gold R.Z. The male factor in fertility and infertility. III. An analysis of motile activity in the spermatozoa of 1000 fertile men and 1000 men in infertile marriage.Fertil Steril. 1951; 2: 187-204Abstract Full Text PDF PubMed Google Scholar, 8MacLeod J. Wang Y. Male fertility potential in terms of semen quality: a review of the past, a study of the present.Fertil Steril. 1979; 31: 103-116Abstract Full Text PDF PubMed Google Scholar, 9Macleod J. Gold R.Z. The male factor in fertility and infertility. II. Spermatozoon counts in 1000 men of known fertility and in 1000 cases of infertile marriage.J Urol. 1951; 66: 436-449Abstract Full Text PDF PubMed Scopus (241) Google Scholar) in 1,000 men of known fertility and 1,000 couples with subfertility. More recent studies, in 2001, evaluating male partners of fertile and infertile couples suggested that lower thresholds of sperm concentration <13.6 million/mL, motility <32%, and normal morphology 4,500 men in 14 countries, including prospective and retrospective studies on fertile men and men of unknown fertility. It is important to note that all the centers used the WHO manual for semen and sperm analyses. Data from men with proven fertility whose partners had a time-to-pregnancy of 5th percentile of the WHO recommended values) indicates that the male partner may not be the primary problem for the infertile couple. Focus should be first on the female partner. Whereas a semen sample that has triple defects—low sperm count, poor motility, and abundance of abnormal sperm morphology—indicates that male factor infertility is likely. Although specific approaches to the treatment of male factor infertility are very few, they need to be investigated during the workup of the female partner. Prospective studies (33Bonde J.P. Ernst E. Jensen T.K. Hjollund N.H. Kolstad H. Henriksen T.B. et al.Relation between semen quality and fertility: a population-based study of 430 first-pregnancy planners.Lancet. 1998; 352: 1172-1177Abstract Full Text Full Text PDF PubMed Scopus (571) Google Scholar, 34Zinaman M.J. Brown C.C. Selevan S.G. Clegg E.D. Semen quality and human fertility: a prospective study with healthy couples.J Androl. 2000; 21: 145-153PubMed Google Scholar, 35Buck Louis G.M. Sundaram R. Schisterman E.F. Sweeney A. Lynch C.D. Kim S. et al.Semen quality and time to pregnancy: the Longitudinal Investigation of Fertility and the Environment Study.Fertil Steril. 2014; 101: 453-462Abstract Full Text Full Text PDF PubMed Scopus (120) Google Scholar) in couples who stopped contraceptive use showed that sperm count, total sperm number, and percent morphologically normal spermatozoa can predict time-to-pregnancy, which is a surrogate marker for fecundity. Spermatozoa have to undergo many changes before fertilization can occur. For IVF, spermatozoa must have adequate motility, propelled mainly by adenosine triphosphate (ATP), generated from glycolysis and not from the mitochondria. Sperm mitochondria are important for calcium homeostasis and for generation of controlled levels of reactive oxygen species necessary for normal sperm function (45Amaral A. Lourenco B. Marques M. Ramalho-Santos J. Mitochondria functionality and sperm quality.Reproduction (Cambridge, England). 2013; 146: R163-R174Crossref PubMed Scopus (300) Google Scholar, 46Piomboni P. Focarelli R. Stendardi A. Ferramosca A. Zara V. The role of mitochondria in energy production for human sperm motility.Int J Androl. 2012; 35: 109-124Crossref PubMed Scopus (246) Google Scholar). During the transit in the female reproductive tract spermatozoa undergo capacitation. The process of capacitation involves generation of adenyl cyclase, which activates protein kinase A, resulting in sperm protein tyrosine phosphorylation, enabling spermatozoa to acquire fertilizing capacity. Spermatozoa then undergo acrosome reaction and hyperactivation when in contact with the ZP (47Bailey J.L. Factors regulating sperm capacitation.Syst Biol Reprod Med. 2010; 56: 334-348Crossref PubMed Scopus (113) Google Scholar, 48Evans J.P. Sperm–egg interaction.Annu Rev Physiol. 2012; 74: 477-502Crossref PubMed Scopus (64) Google Scholar). Recent studies (49Cho C. Testicular and epididymal ADAMs: expression and function during fertilization.Nat Rev Urol. 2012; 9: 550-560Crossref PubMed Scopus (59) Google Scholar, 50Okabe M. The cell biology of mammalian fertilization.Development. 2013; 140: 4471-4479Crossref PubMed Scopus (123) Google Scholar) using advanced technology showed that spermatozoa can penetrate the cumulus without undergoing the acrosome reaction. Spermatozoa must be coated with the sperm surface protein ADAM3 to allow passage through the cumulus and binding to the ZP (49Cho C. Testicular and epididymal ADAMs: expression and function during fertilization.Nat Rev Urol. 2012; 9: 550-560Crossref PubMed Scopus (59) Google Scholar). These processes enable a sperm cell to penetrate the ZP and begin the process of fertilization of the oocyte. The fertilization of the ooctye requires at least the presence of IZUMO 1 on the spermatozoa and CD 9 on the ooctye (50Okabe M. The cell biology of mammalian fertilization.Development. 2013; 140: 4471-4479Crossref PubMed Scopus (123) Google Scholar, 51Inoue N. Ikawa M. Okabe M. The mechanism of sperm-egg interaction and the involvement of IZUMO1 in fusion.Asian J Androl. 2011; 13: 81-87Crossref PubMed Scopus (47) Google Scholar). Thus it is clear that examination of the semen and the spermatozoa in the ejaculate cannot assess: [1] the process of capacitation of the spermatozoa in the female reproductive tract, [2] the acquisition of sperm surface proteins that are required for ZP binding and penetration, and [3] the ability to fertilize the egg. Some of these sperm function tests are described in other articles on biomarkers of spermaotozoal fertilizing capacity. There are many sperm function tests including the sperm oocyte penetration test, hemizona assay, stimulation of acrosome reaction (AR), hyperactivated motility assessment using computer-assisted semen analysis, and in vitro capacitation tests that may assess each step that spermatozoa must undergo before fertilization occurs. These sperm function tests have been shown to be associated with fertilization in vitro but none of these in vitro tests have consistently predicted the time-to-pregnancy better than sperm concentration and morphology. Sperm DNA integrity was not associated with fecundity of the couple (35Buck Louis G.M. Sundaram R. Schisterman E.F. Sweeney A. Lynch C.D. Kim S. et al.Semen quality and time to pregnancy: the Longitudinal Investigation of Fertility and the Environment Study.Fertil Steril. 2014; 101: 453-462Abstract Full Text Full Text PDF PubMed Scopus (120) Google Scholar). Because infertility is a complex process involving male and female factors, it will not be possible to predict fertility using parameters from either partner alone unless there is azoospermia in the man or premature ovarian failure (POF) in the woman. Female fecundity contributes significantly to the fertility potential of the couple (5te Velde E.R. Eijkemans R. Habbema H.D. Variation in couple fecundity and time to pregnancy, an essential concept in human reproduction.Lancet. 2000; 355: 1928-1929Abstract Full Text Full Text PDF PubMed Scopus (93) Google Scholar). In a prospective study (52Van Geloven N. van der Veen F. Bossuyt P.M. Hompes P.G. Zwinderman A.H. Mol B.W. Can we distinguish between infertility and subfertility when predicting natural conception in couples with an unfulfilled child wish?.Hum Reprod. 2013; 28: 658-665Crossref PubMed Scopus (15) Google Scholar) based on 3,917 couples presenting with unexplained infertility, a mixed model was used to distinguish couples who may have chance of natural conception and those who would be infertile without using ART. The statistical mixed model estimated that 47% of the couple were infertile, only female age (odds ratio, 1.11; 95% CI 1.03–1.19) and previous pregnancy (odds ratio, 0.22; 95% CI 0.07–0.67) were significantly related to infertility and semen quality was not a statistically important factor for unexplained infertility. For a clinician who treats infertile couples, the questions are [1] Is there a problem with the male partner? [2] How significant is the abnormality? [3] Is there a cause of this abnormality? [4] Can the abnormality be treated? [5] Should the couple be referred for ICSI or IVF? [6] Can sperm biomarkers predict the success of ICSI and IVF? and [7] Will the defect in the male factor affect the progeny? Performing a routine semen analysis will provide leads to whether the problem may be present in the male partner and an estimate of the severity of the problem. To find out the cause of the abnormality will require further testing that may include assessing the general health of the male partner (smoking, obesity, hypogonadism, chronic diseases), genetic testing to exclude Y chromosome microdeletions and other common genetic defects, and excluding obstructive causes that can be amenable to treatment. Sperm function testing is not frequently done as the couple with moderate-to-severe nonobstructive oligozoospermia is usually referred for ICSI and IVF. At this stage, genetic testing should have been done and counseling, if necessary, should have been provided to the couple. Future sperm function tests need to accurately predict the success of fertilization in vitro and whether the progeny will be healthy. This may include using epigenetics and deep sequencing studies for clinical diagnosis of male factor infertility to discover spermatozoal epigenetic disorders (53Boissonnas C.C. Jouannet P. Jammes H. Epigenetic disorders and male subfertility.Fertil Steril. 2013; 99: 624-631Abstract Full Text Full Text PDF PubMed Scopus (90) Google Scholar, 54Gannon J.R. Emery B.R. Jenkins T.G. Carrell D.T. The sperm epigenome: implications for the embryo.Adv Exp Med Biol. 2014; 791: 53-66Crossref PubMed Scopus (68) Google Scholar, 55Klaver R. Gromoll J. Bringing epigenetics into the diagnostics of the andrology laboratory: challenges and perspectives.Asian J Androl. 2014; 16: 669-674Crossref PubMed Scopus (35) Google Scholar), spermatozoal small noncoding RNA defects (56De Mateo S. Sassone-Corsi P. Regulation of spermatogenesis by small non-coding RNAs: role of the germ granule.Semin Cell Dev Biol. 2014; 29: 84-92Crossref PubMed Scopus (55) Google Scholar, 57Jodar M. Selvaraju S. Sendler E. Diamond M.P. Krawetz S.A. The presence, role and clinical use of spermatozoal RNAs.Hum Reprod Update. 2013; 19: 604-624Crossref PubMed Scopus (236) Google Scholar), and other subtle genetic abnormalities that may impact fertilizing potential and the outcome of the progeny (58Hotaling J. Carrell D.T. Clinical genetic testing for male factor infertility: current applications and future directions.Andrology. 2014; 2: 339-350Crossref PubMed Scopus (92) Google Scholar).