Do the results of semen analysis predict future fertility? A survival analysis study

Can semen parameters predict pregnancy outcomes?

Semen analysis is an integral component of the evaluation and management of men with infertility. Although it is important for patient counseling and clinical decision making, a conventional semen analysis cannot reliably predict the chance of pregnancy or differentiate fertile vs. infertile men (except in the most extreme cases). Advanced, nonstandard sperm functional tests may provide additional discriminatory and prognostic power; however, further research is needed to determine how to best incorporate these tests into modern clinical practice. Therefore, the primary applications of a conventional semen analysis should be to judge the severity of infertility, estimate the effects of future therapy, and measure the response to current therapy.

Obesity and Male Infertility: True, True, and Unrelated?

While the prevalence of obesity has rapidly increased worldwide, there has also been a notable decline in semen parameters over the last several decades. While obesity can negatively impact reproductive hormones, many studies have sought a link between rising obesity and decreased male fertility potential. Nonetheless, few data support a direct link between the two. The focus on obesity as a causative factor in male infertility can potentially result in patient harm through delayed fertility treatment and missed diagnoses. This review investigates the associations between obesity and male infertility and why a potential direct link has been elusive and may not exist. Additionally, indirect mechanisms that may link the two will be reviewed and treatment options for obese infertile men presenting for evaluation will briefly be discussed.

The male infertility evaluation still matters in the era of high efficacy assisted reproductive technology

Today's reproductive endocrinology and infertility providers have many tools at their disposal when it comes to achieving pregnancy. In the setting of highly efficacious assisted reproductive technology, it is natural to assume that male factor infertility can be overcome by acquiring sperm and then bypassing the male evaluation. In this review, we go through guideline statements and a stepwise male factor infertility evaluation to propose that a thorough male evaluation remains important to optimize pregnancy and live birth. The foundation of this parallel evaluation is referral to a reproductive urologist for the optimization of the male partner, for advanced diagnostics and interventions, and for the detection of other underlying male pathology. We also discuss what future developments might have an impact on the workup of the infertile male.

Semen parameter thresholds and time-to-conception in subfertile couples: how high is high enough?

STUDY QUESTION

What thresholds for total sperm count, sperm concentration, progressive motility, and total progressive motile sperm count (TPMC) are associated with earlier time-to-conception in couples undergoing fertility evaluation?

SUMMARY ANSWER

Values well above the World Health Organization (WHO) references for total sperm count, concentration, and progressive motility, and values up to 100 million for TPMC were consistently associated with earlier time-to-conception and higher conception rates.

WHAT IS KNOWN ALREADY

Although individual semen parameters are generally not able to distinguish between fertile and infertile men, they can provide clinically useful information on time-to-pregnancy for counseling patients seeking fertility treatment. Compared to the conventional semen parameters, TPMC might be a better index for evaluating the severity of male infertility.

STUDY DESIGN, SIZE, DURATION

We used data from a longitudinal cohort study on subfertile men from 2002 to 2017 and included 6061 men with initial semen analysis (SA) in the study.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Men from subfertile couples who underwent a SA within the study period were included, and 5-year follow-up data were collected to capture conception data. Couples were further categorized into two subgroups: natural conception (n = 5126), after separating those who achieved conception using ART or IUI; natural conception without major female factor (n = 3753), after separating those with severe female factor infertility diagnoses. TPMC was calculated by multiplying the semen volume (ml) by sperm concentration (million/ml) and the percentage of progressively motile sperm (%). Cox proportional hazard models were used to report hazard ratios (HRs) with 95% CIs before and after adjusting for male age, the number of previous children before the first SA, and income. Using the regression tree method, we calculated thresholds for total sperm count, sperm concentration, progressive motility, and TPMC to best differentiate those who were more likely to conceive within 5 years after first SA from those less likely to conceive. We also plotted continuous values of semen parameters in predicting 5-year conception rates and time-to-conception.

MAIN RESULTS AND THE ROLE OF CHANCE

Overall, the median time to conception was 22 months (95% CI: 21-23). A total of 3957 (65%) couples were known to have achieved conception within 5 years of the first SA. These patients were younger and had higher values of sperm concentration, progressive motility, and TPMC. In the overall cohort, a TPMC of 50 million best differentiated men who were more likely to father a child within 5 years. Partners of men with TPMC ≥50 million had a 45% greater chance of conception within 5 years in the adjusted model (HR: 1.45; 95% CI: 1.34-1.58) and achieved pregnancy earlier compared to those men with TPMC < 50 million (median 19 months (95% CI: 18-20) versus 36 months (95% CI: 32-41)). Similar results were observed in the natural conception cohort. For the natural conception cohort without major female factor, the TPMC cut-off was 20 million. In the visual assessment of the graphs for the continuous semen parameter values, 5-year conception rates and time-to-conception consistently plateaued at higher values of sperm concentration, total sperm count, progressive motility, and TPMC compared to the WHO reference levels and our calculated thresholds. For TPMC, values up to 100-150 million were still associated with a better conception rate and time-to-conception in the visual assessment of the curves.

LIMITATIONS, REASONS FOR CAUTION

There was limited information on female partners and potential for inaccuracies in capturing less severe female infertility diagnoses. Also we lacked details on assisted pregnancies achieved outside of our healthcare network (with possible miscoding as 'natural conception' in our cohort). We only used the initial SA and sperm morphology, another potentially important parameter, was not included in the analyses. We had no information on continuity of pregnancy attempts/intention, which could affect the time-to-conception data. Finally, most couples had been attempting conception for >12 months prior to initiating fertility treatment, so it is likely that we are underestimating time to conception. Importantly, our data might lack the generalizability to other populations.

WIDER IMPLICATIONS OF THE FINDINGS

Our results suggest that a TPMC threshold of 50 million sperm provided the best predictive power to estimate earlier time-to-conception in couples evaluated for male factor infertility. Higher values of sperm count, concentration and progressive motility beyond the WHO references were still associated with better conception rates and time-to-conception. This provides an opportunity to optimize semen parameters in those with semen values that are low but not abnormal according to the WHO reference values. These data can be used to better inform patients regarding their chances of conception per year when SA results are used for patient counseling.

STUDY FUNDING/COMPETING INTEREST(S)

None.

TRIAL REGISTRATION NUMBER

N/A.

Correlation of oxidation reduction potential and total motile sperm count: its utility in the evaluation of male fertility potential

Oxidative stress (OS) is detrimental to sperm functions, and the oxidation reduction potential (ORP) is a good measure of OS as it considers the balance between oxidants and reductants. Total motile sperm count (TMSC) is viewed as the single most important semen analysis parameter that can predict male infertility severity, and its correlation with ORP has never been undertaken. The objectives of this study were to assess the correlation between ORP and TMSC, to identify the ORP cutoff value based on the TMSC result, and to compare this cutoff value with previously reported ORP cutoff values in literature. One thousand one hundred and sixty-eight infertile patients and 100 fertile controls were enrolled. Demographic and semen data of the participants were retrieved and analyzed. Wilcoxon's rank-sum test compared variables between infertile men and fertile controls; Spearman's correlation assessed the static ORP (sORP)-TMSC relationship for the whole sample and among each group individually. Using a 20×10⁶ TMSC threshold, receiver operator characteristic (ROC) analysis determined the sORP cutoff associated with the highest predictive values. TMSC was significantly negatively correlated with sORP across all participants (r = 0.86, P < 0.001), among infertile patients (r = 0.729, P < 0.001), and among fertile controls (r = 0.53, P < 0.001). A 20-million TMSC threshold determined an sORP cutoff value of 2.34 mV/10⁶ sperm/ml to be associated with 82.9% sensitivity, 82.8% specificity, 91.5% positive predictive value (PPV), 68.5% negative predictive value (NPV), and 82.9% overall accuracy. Compared with previously reported cutoff values in searched literature, the 2.34 mV/10⁶ sperm/ml cutoff value identified in our study yielded the highest overall diagnostic accuracy in the evaluation of infertile men.

Diagnostic performance of discontinuous density gradient centrifugation for estimating human semen quality

BACKGROUND

Semen analysis plays an important role in the diagnosis of male infertility. However, many studies have demonstrated that the current methods of semen analysis are inefficient for assessing male fertility.

OBJECTIVE

To test whether prior discontinuous density gradient centrifugation (DDCG) improves the performance of semen analysis in diagnosing male infertility.

MATERIALS AND METHODS

Infertile men and fertile men were recruited from the clinic. Pre- and post-DDGC values for the semen parameters of sperm concentration, total sperm number, percent total motility, percent progressive motility, percent normal sperm morphology, and sperm DNA fragmentation rate were compared.

RESULTS

A total of 528 men (252 infertile men and 276 fertile men) were enrolled in the present study. After DDGC, sensitivity was significantly increased for sperm concentration, total sperm number, and sperm morphology (P < .01); specificity was significantly increased for progressive motility and sperm morphology (P < .01); and diagnostic accuracy was significantly improved for all of these parameters (area under the curve (AUC): P < .01). Total motility and sperm DNA fragmentation rate exhibited no obvious change in sensitivity, specificity or accuracy after DDGC (all P > .01). For the combination of all these semen parameters, diagnostic accuracy improved significantly after DDGC (AUC: P < .01). In a multiple regression analysis, only sperm morphology and sperm DNA fragmentation rate had P values less than 0.05 before DDGC, whereas all parameters except total sperm number contributed to the equation after DDGC.

DISCUSSION

DDGC is a mature, standardized procedure for clinical commonly used to optimize spermatozoa. The diagnostic accuracy of semen analysis was significantly improved after DDGC, which indicated that assessing "functional spermatozoa" might be a more suitable method for semen analysis than the WHO 2010 criteria.

CONCLUSION

Assessing semen parameters after DDGC might improve their diagnostic accuracy for male infertility.

Total motile sperm count has a superior predictive value over the WHO 2010 cut-off values for the outcomes of intracytoplasmic sperm injection cycles

The objective of this study was to compare (i) the intracytoplasmic sperm injection outcomes among groups with different total motile sperm count ranges, (ii) the intracytoplasmic sperm injection outcomes between groups with normal and abnormal total motile sperm count, and (iii) the predictive values of WHO 2010 cut-off values and pre-wash total motile sperm count for the intracytoplasmic sperm injection outcomes, in couples with male infertility. This study included data from 518 patients undergoing their first intracytoplasmic sperm injection cycle as a result of male infertility. Couples were divided into five groups according to their total motile sperm count: Group I, total motile sperm count <1 × 10(6) ; group II, total motile sperm count 1-5 × 10(6) ; group III, total motile sperm count 5-10 × 10(6) ; group IV, total motile sperm count 10-20 × 10(6) ; and group V, total motile sperm count >20 × 10(6) (which was considered a normal total motile sperm count value). Then, couples were grouped into an abnormal and normal total motile sperm count group. The groups were compared regarding intracytoplasmic sperm injection outcomes. The predictive values of WHO 2010 cut-off values and total motile sperm count for the intracytoplasmic sperm injection outcomes were also investigated. The fertilization rate was lower in total motile sperm count group I compared to total motile sperm count group V (72.5 ± 17.6 vs. 84.9 ± 14.4, p = 0.011). The normal total motile sperm count group had a higher fertilization rate (84.9 ± 14.4 vs. 81.1 ± 15.8, p = 0.016) and lower miscarriage rate (17.9% vs. 29.5%, p = 0.041) compared to the abnormal total motile sperm count group. The total motile sperm count was the only parameter that demonstrated a predictive value for the formation of high-quality embryos on D2 (OR: 1.18, p = 0.013), formation of high-quality embryos on D3 (OR: 1.12, p = 0.037), formation of blastocysts on D5 (OR: 1.16, p = 0.011), blastocyst expansion grade on D5 (OR: 1.27, p = 0.042), and the odds of miscarriage (OR: 0.52, p < 0.045). The total motile sperm count has a greater predictive value than the WHO 2010 cut-off values for laboratory results and pregnancy outcomes in couples undergoing intracytoplasmic sperm injection as a result of male infertility.

Total motile sperm count: a better indicator for the severity of male factor infertility than the WHO sperm classification system

STUDY QUESTION

Does the prewash total motile sperm count (TMSC) have a better predictive value for spontaneous ongoing pregnancy (SOP) than the World Health Organization (WHO) classification system?

SUMMARY ANSWER

The prewash TMSC shows a better correlation with the spontaneous ongoing pregnancy rate (SOPR) than the WHO 2010 classification system.

WHAT IS KNOWN ALREADY

According to the WHO classification system, an abnormal semen analysis can be diagnosed as oligozoospermia, astenozoospermia, teratozoospermia or combinations of these and azoospermia. This classification is based on the fifth percentile cut-off values of a cohort of 1953 men with proven fertility. Although this classification suggests accuracy, the relevance for the prognosis of an infertile couple and the choice of treatment is questionable. The TMSC is obtained by multiplying the sample volume by the density and the percentage of A and B motility spermatozoa.

STUDY DESIGN, SIZE, DURATION

We analyzed data from a longitudinal cohort study among unselected infertile couples who were referred to three Dutch hospitals between January 2002 and December 2006. Of the total cohort of 2476 infertile couples, only the couples with either male infertility as a single diagnosis or unexplained infertility were included (n = 1177) with a follow-up period of 3 years.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In all couples a semen analysis was performed. Based on the best semen analysis if more tests were performed, couples were grouped according to the WHO classification system and the TMSC range, as described in the Dutch national guidelines for male infertility. The primary outcome measure was the SOPR, which occurred before, during or after treatments, including expectant management, intrauterine insemination, in vitro fertilization or intracytoplasmic sperm injection. After adjustment for the confounding factors (female and male age, duration and type of infertility and result of the postcoital test) the odd ratios (ORs) for risk of SOP for each WHO and TMSC group were calculated. The couples with unexplained infertility were used as reference.

MAIN RESULTS AND THE ROLE OF CHANCE

A total of 514 couples did and 663 couples did not achieve a SOP. All WHO groups have a lower SOPR compared with the unexplained group (ORs varying from 0.136 to 0.397). Comparing the couples within the abnormal WHO groups, there are no significant differences in SOPR, except when oligoasthenoteratozoospermia is compared with asthenozoospermia [OR 0.501 (95% CI 0.311-0.809)] and teratozoospermia [OR 0.499 (95% CI: 0.252-0.988)], and oligoasthenozoospermia is compared with asthenozoospermia [OR 0.572 (95% CI: 0.373-0.877)]. All TMSC groups have a significantly lower SOPR compared with the unexplained group (ORs varying from 0.171 to 0.461). Couples with a TMSC of <1 × 10(6) and 1-5 × 10(6) have significantly lower SOPR compared with couples with a TMSC of 5-10 × 10(6) [respectively, OR 0.371 (95% CI: 0.215-0.64) and OR 0.505 (95% CI: 0.307-0.832)].

LIMITATIONS, REASON FOR CAUTION

To include all SOPs during the follow-up period of 3 years, couples were not censured at the start of treatment.

WIDER IMPLICATIONS OF THE FINDINGS

Roughly, three prognostic groups can be discerned: couples with a TMSC <5, couples with a TMSC between 5 and 20 and couples with a TMSC of more than 20 × 10(6) spermatozoa. We suggest using TMSC as the method of choice to express severity of male infertility.

STUDY FUNDING/COMPETING INTERESTS

None.

Unexplained male infertility: diagnosis and management

Unexplained male infertility is a diagnosis reserved for men in whom routine semen analyses results are within normal values and physical as well as endocrine abnormalities were ruled out. In addition to erectile problems and coital factors, immunologic causes and sperm dysfunction may contribute to such condition. New etiologies of unexplained male infertility include low level leukocytospermia and mitochondrial DNA polymerase gene polymorphism. Contemporary andrology may reveal cellular and sub-cellular sperm dysfunctions which may explain subfertility in such cases, thus aiding the clinician to direct the further work-up, diagnosis and counseling of the infertile male. The objective of this article is to highlight the concept of unexplained male infertility and focuses on the diagnosis and treatment of this condition in the era of modern andrology and assisted reproductive techniques. Extensive literature review was performed using the search engines: Pubmed, Science-direct, Ovid and Scopus.

Effects of Anethum graveolens L. on fertility in male rats

OBJECTIVES

The effects of Anethum graveolens seed extract on fertility of male rats were investigated.

METHODS

Male Wistar rats were divided into five groups according to the treatment they received during 42 days: control, low dose (0.5 g/kg) and high dose (5 g/kg) of aqueous extracts, and low dose (0.045 g/kg) and high dose (0.45 g/kg) of ethanol extracts of Anethum graveolens seed. Sperm count and motility and testosterone concentration were measured. Sections of the testes, epididymis, and seminal vesicles were stained with peroxidase-conjugated lectins of Ulex europaeus agglutinin, peanut agglutinin, Dolichos biflorus agglutinin, soy bean agglutinin and concanavalin A. The treated male rats were mated with females and the crown-rump lengths and weights of their newborn pups were measured.

RESULTS

No significant differences in sperm count, sperm motility or testosterone concentration were observed in the experimental groups. However, female rats did not become pregnant after mating with rats given the high dose of the ethanol extract. The distribution of terminal sugars on the epithelial surface of the reproductive structures decreased in the experimental groups.

CONCLUSION

Anethum graveolens extract decreased fertility rate by modifying some terminal sugars on the cell surface of male reproductive organs involved in sperm maturation, capacitation and oocyte recognition.

Presence of DNA of adeno-associated virus in subfertile couples, but no association with fertility factors

BACKGROUND

Based on previous reports suggesting a role of adeno-associated virus (AAV) in miscarriage, the prevalence of AAV DNA in genital tracts of male and female partners of subfertile couples was determined to assess a potential association of AAV infection with clinically relevant parameters of male and female fertility.

METHODS

A prospective study was performed in the outpatient infertility clinic of a university-based hospital. Semen samples and endocervical material obtained from 146 male and 134 female partners of asymptomatic subfertile couples were analyzed for the presence of AAV DNA (using nested PCR). Patients' medical histories and details of clinical examinations were recorded. Semen quality, including sperm functional capacity and the presence of antisperm antibodies (ASA) and seminal white blood cells (WBC), was assessed in aliquots of the same ejaculate. Detailed examinations of the cervical factor and other variables of female subfertility were performed. Both partners were screened for bacterial infection.

RESULTS

The presence of AAV DNA in semen was not significantly related to semen quality, including sperm functional capacity or local ASA, nor was it coupled to the presence of AAV in the endocervical material of female partners. The presence of AAV DNA was not associated with the presence of other micro-organisms of the lower genital tract or with seminal WBC in men. AAV DNA in endocervical material was not related to a reduced quality of cervical mucus or to other female infertility factors.

CONCLUSIONS

The presence of AAV DNA in semen samples or endocervical swabs showed no significant association with clinically relevant infertility factors. However, longitudinal studies may clarify previous suggestions of an influence of AAV infection on early pregnancy problems.

An update on the clinical assessment of the infertile male. [corrected]

Male infertility is directly or indirectly responsible for 60% of cases involving reproductive-age couples with fertility-related issues. Nevertheless, the evaluation of male infertility is often underestimated or postponed. A coordinated evaluation of the infertile male using standardized procedures improves both diagnostic precision and the results of subsequent management in terms of effectiveness, risk and costs. Recent advances in assisted reproductive techniques (ART) have made it possible to identify and overcome previously untreatable causes of male infertility. To properly utilize the available techniques and improve clinical results, it is of the utmost importance that patients are adequately diagnosed and evaluated. Ideally, this initial assessment should also be affordable and accessible. We describe the main aspects of male infertility evaluation in a practical manner to provide information on the judicious use of available diagnostic tools and to better determine the etiology of the most adequate treatment for the existing condition.

Is sperm evaluation useful in predicting human fertility?

Traditionally, the diagnosis of male infertility has relied upon microscopic assessment and biochemical assays to determine human semen quality. The conventional parameters given most importance have been the concentration, motility, and morphology of sperm in the ejaculate. Most laboratories also include ‘sperm suitability’ tests where the subpopulations of sperm more likely to finish the marathon journey to the oocyte are separated by density centrifugation. These tests are essential to provide the fundamental information on which clinicians base their initial diagnosis. However, none of these parameters addresses sperm function and their clinical value in predicting fertility is questionable. The advent of intracytoplasmic sperm injection (ICSI) has further reduced the significance and perceived need for sperm quality tests since ICSI requires only one sperm, not subject to classic, or indeed any, tests for the procedure to be successful. Over the past decade, a number of laboratory tests have been developed to determine properties of sperm function. These include quantitative sperm motion parameters, capacitation, basal and induced acrosome reactions, sperm–zona pellucida interactions and nuclear and mitochondrial sperm DNA but few have been adopted into routine clinical use. International collaborations should be initiated to develop clinically relevant molecular and functional tests with agreed protocols and clinical thresholds as a matter of urgency.

Evaluation of acrosomal status and sperm viability in fresh and cryopreserved specimens by the use of fluorescent peanut agglutinin lectin in conjunction with hypo-osmotic swelling test

OBJECTIVE

In this study, we evaluated whether the hypo-osmotic swelling test (HOST) can be used as a vital marker in combination with peanut agglutinin (PNA) - labeling in fresh and cryopreserved spermatozoa.

MATERIALS AND METHODS

Human sperm populations were exposed to a hypo-osmotic medium for 60 minutes, and then incubated in a 1 microg/mL solution of the fluorescent dye Hoescht 33258 (H33258) for 10 minutes. Excess stain was removed by washing in phosphate-buffered saline (PBS) solution, and the pellet was resuspended in 100 microL of culture medium. Twenty microliters of this solution were subsequently smeared on a microscope slide, and fixed in ice-cold methanol to permeabilize the sperm membranes. The fixed smears were finally incubated in a 40-microg/mL FITC-PNA solution for 20 minutes. Simultaneous assessment of acrosome and viability scores was done in a fluorescent microscope equipped with appropriate filters and phase contrast illumination. The same slide was examined for FITC-PNA labeling, tail swelling, and for Hoechst-33258 staining by interchanging the filters and phase contrast optics.

RESULTS

In fresh specimens, HOST was found to provide viability assessments comparable to those obtained using the H33258 method (r = 0.95). However, the results of HOST and H33258 were not correlated in cryopreserved specimens (r = 0.22). There was no alteration of PNA-labeling due to the HOST or H33258.

CONCLUSIONS

FITC-PNA labeling in conjunction with the visualization of the morphological change induced by exposure to hypo-osmotic solution provides a simple but effective method for establishing the state of acrosomal membrane and viability in fresh human spermatozoa, but this technique is not reliable for cryopreserved ones.

Regression analyses and motile sperm subpopulation structure study as improving tools in boar semen quality analysis

A precise estimation of the fertilizing ability of a boar ejaculate would be very useful to improve pig assisted reproduction results. For this purpose, we tested the mathematical combination of several parameters of the boar semen quality analysis, including the computer-assisted semen motility analysis (CASA), as a predictive fertility tool. The utilized mathematical relations among parameters were logistic and linear regressions. Two mathematical models obtained by logistic regression involving Osmotic Resistance Test (ORT Test), Hyperosmotic Resistance Test (HRT Test) and viability of fresh samples, showed a significant (P<0.05) correlation between semen characteristics and conception rate. However, none of the obtained models produced a significant correlation model between semen characteristics and prolificacy. The CASA analyses show that three separate subpopulations of spermatozoa with different motility characteristics coexist in boar ejaculates. There were significant (P<0.001) differences in the distribution of these subpopulations among boars, but no clear relationship between motile subpopulation structure and fertility was obtained. Our results support the belief that the predictive use of the results obtained in a standard boar semen quality analysis can reasonably be achieved by applying logistic correlation analyses among several function parameters of boar semen quality analysis and in vivo conception rates obtained after artificial insemination (AI).

Relationship between thirty post-thaw spermatozoal characteristics and the field fertility of 11 high-use Australian dairy AI sires

This study determined the relationship between two measures of field fertility of 11 high-use Australian artificial insemination (AI) dairy bulls and thirty standard laboratory assessments of spermatozoal post-thaw viability. The two measures of field fertility used, conception rates (cCR) and non-return rates (cNRR), were both corrected for all major non-bull variables. Sperm viability assessments were conducted on semen collected within the same season as that used to derive the field fertility estimates. These assessments measured sperm concentration, motility, morphology and membrane integrity at thawing, after 2h incubation and after the swim-up sperm selection procedure. Derivations of these measures and in vitro embryo fertilizing and developmental capacity were also determined. The Genstat Statistical Package [Genstat 5 Release 4.2 Reference Manual, VSN International, Oxford, 2000] was used to conduct an analysis of variance on the viability parameters across semen straws and bulls, and to calculate the strength of correlation between each semen parameter, cNRR and cCR in a correlation matrix. Step forward multiple regression identified the combination of semen parameters that were most highly correlated with cCR and with cNRR. The sperm parameters identified as being most predictive of cCR were the percentage of morphologically normal sperm immediately post-thaw (zeroNorm), the number of morphologically normal sperm after the swim-up procedure (nSuNorm), and the rate of zygote cleavage in vitro (Clv); the predictive equation formed by these parameters accounted for 70% of variance. The predictive equation produced for cNRR contained the variables zeroNorm, the proportion of membrane intact sperm after 2h incubation at 37 degrees C (twoMem) and Clv and accounted for 76.5% of the variation. ZeroNorm was found to be consistent across straws and semen batches within-bull and the sperm parameter with the strongest individual predictive capacity for both cCR (P=0.1) and cNRR (P=0.001). Post-thaw sperm parameters can be used to predict field fertility of Australian dairy sires; the calculated predictive equations are particularly useful for identifying and monitoring bulls of very high and very low potential fertility within a group.

Comprehensive office evaluation in the new millennium

The success of a comprehensive office-based evaluation of male-factor infertility depends on the physician's thorough understanding of risk assessment in the history, identification of pertinent physical examination findings, and correct assessment of laboratory data. Office-based ultrasonographic techniques have already increased the urologist's ability to visualize suspected anatomic abnormalities, and the use of functional tests of sperm has given greater depth to the limited, but essential, prognostic capabilities of the routine semen analysis.

Progesterone Receptor as an Indicator of Sperm Function

Expression of progesterone receptor (PR) localization on spermatozoa was determined in men with normal and abnormal spermiograms. Studies were also carried out to evaluate the potential of PR as a marker of sperm function. Progesterone receptor expression on spermatozoa from men with normozoospermia (n = 8), oligozoospermia (n = 7), asthenozoospermia (n = 8), oligoasthenozoospermia (n = 7), and teratozoospermia (n = 11) was analyzed using an immunocytochemical method with monoclonal antibodies against PR, and flow cytometry using a cell-impermeable fluorescein-tagged progesterone coupled to BSA complex (P-FITC-BSA). Both methods revealed significantly fewer (P < 0.05) PR-positive spermatozoa in men with oligozoospermia, asthenozoospermia, oligoasthenozoospermia, and teratozoospermia compared with men with normozoospermia, thereby suggesting that down-regulation of PR expression in spermatozoa may be one of the causes of male infertility. Spermatozoa from men with normozoospermia (n = 12), oligozoospermia (n = 12), asthenozoospermia (n = 12), oligoasthenozoospermia (n = 9), and teratozoospermia (n = 10) were exposed to low osmotic conditions in the hypoosmotic swelling (HOS) test and then analyzed for PR expression using P-FITC-BSA complex. A significantly higher percentage (P < 0.05) of spermatozoa with physiologically active plasma membrane (HOS+) lacked PR expression (HOS+PR-) in all categories of men with infertility, thereby suggesting that compared to the HOS test, PR expression is a better indicator of sperm function. Furthermore, PR expression in spermatozoa showed a strong (P < 0.05) positive correlation with their ability to undergo an in vitro acrosome reaction. This was observed in all study groups (i.e., normozoospermia, r = 0.8545; oligozoospermia, r = 0.8711; asthenozoospermia, r = 0.7645; oligoasthenozoospermia, r = 0.9003; and teratozoospermia, r = 0.8676). This suggests a potential role for PR in the events leading to the acrosome reaction in sperm.

Chlamydia trachomatis infection in male partners of infertile couples: incidence and sperm function

Chlamydia trachomatis infection is one of the most common sexually transmitted diseases. Its effect on male fertility, however, is still controversial. In this study, 284 male partners of infertile couples consulting the Center of Studies in Reproductive Biology (CEBRE) were analyzed. The incidence of C. trachomatis infection among male partners of infertile couples was 38.6%. There were no significant differences between infected and noninfected infertile men in any of the sperm parameters assessed (sperm concentration, motility and morphology). The results of the three bioassays developed to evaluate sperm physiology, namely spermatozoa-zona pellucida binding, acrosome reaction stimulated with human follicular fluid and zona-free hamster oocyte penetration, showed no differences between infected and noninfected men. Electron microscopy studies suggest that spermatozoa are active agents in the dissemination of the chlamydial infection; they could be acting as 'vehicles' for the pathogens. These, and other results, suggest that the possible effect of C. trachomatis on male fertility is not due to alterations in sperm 'quality' or function, but rather to the transmission of the disease to female partners, causing inflammatory processes and promoting the generation of antisperm antibodies.

Prediction of fecundability from semen analysis: problems in providing an accurate prognosis

Information from semen analysis is used to predict the likelihood that a couple will conceive within a period of time. It is only possible to provide a probability; there can be no certainty. The probability is influenced by a host of factors including semen quality, and studies in large groups or using simple models are required to overcome this. Delayed conception from natural intercourse or poor fertilization at IVF has limited predictive power for a subsequent attempt. The problem is made worse by variations in sperm parameters among different ejaculates from the same man and by differences among groups of patients. Results of studies of potential criteria should be presented in a way that allows the effect of the test result on the probability of conception to be appreciated, and results should be confirmed on independent data sets. When there is potential for fertility, estimation of fecundability can only be approximate; however, progress is possible. Effects of semen quality can be clearly identified in large groups, and computer assisted semen analysis measurements do provide useful additional information for the success of intracervical insemination.

Predicting conception

Infertility is relative. Research into effective treatment must focus on couples with single, identifiable causes for their infertility, and must take into account the effect of chance and time on eventual success. Women with ovulatory infertility, who have no other subfertility factors, can expect normal conception rates when ovulation is restored. Unfortunately, there is no similar simple treatment for male infertility, although complicated and expensive treatment may help. Selection of the couples most likely to benefit from such help will result in the most cost-effective use of scarce resources. Knowledge of duration of infertility and the postcoital test result can help to identify those couples who have a reasonable chance of conception without treatment and those who have virtually no chance without it.

Sperm morphology, motility, and concentration in fertile and infertile men

BACKGROUND

Although semen analysis is routinely used to evaluate the male partner in infertile couples, sperm measurements that discriminate between fertile and infertile men are not well defined.

METHODS

We evaluated two semen specimens from each of the male partners in 765 infertile couples and 696 fertile couples at nine sites. The female partners in the infertile couples had normal results on fertility evaluation. The sperm concentration and motility were determined at the sites; semen smears were stained at the sites and shipped to a central laboratory for an assessment of morphologic features of sperm with the use of strict criteria. We used classification-and-regression-tree analysis to estimate threshold values for subfertility and fertility with respect to the sperm concentration, motility, and morphology. We also used an analysis of receiver-operating-characteristic curves to assess the relative value of these sperm measurements in discriminating between fertile and infertile men.

RESULTS

The subfertile ranges were a sperm concentration of less than 13.5 x 10(6) per milliliter, less than 32 percent of sperm with motility, and less than 9 percent with normal morphologic features. The fertile ranges were a concentration of more than 48.0 x 10(6) per milliliter, greater than 63 percent motility, and greater than 12 percent normal morphologic features. Values between these ranges indicated indeterminate fertility. There was extensive overlap between the fertile and the infertile men within both the subfertile and the fertile ranges for all three measurements. Although each of the sperm measurements helped to distinguish between fertile and infertile men, none was a powerful discriminator. The percentage of sperm with normal morphologic features had the greatest discriminatory power.

CONCLUSIONS

Threshold values for sperm concentration, motility, and morphology can be used to classify men as subfertile, of indeterminate fertility, or fertile. None of the measures, however, are diagnostic of infertility.

The prognostic power of the post-coital test for natural conception depends on duration of infertility

Controversy about the value of the post-coital test (PCT) has prompted us to re-analyse data from 207 couples, originally studied between 1982 and 1983, with at least 12 months' infertility at presentation, complete diagnostic information and exclusion of female factors, to clarify the effect of duration of infertility on the prediction of conception. In couples with less than 3 years infertility and a positive PCT, 68% conceived within 2 years compared with 17% of those with a negative result. After 3 years, corresponding rates were 14% and 11%. The relative risks of conception [95% confidence interval (CI)] calculated using the Cox's proportional hazards model were 0.23 (0.12-0.43) for a negative PCT (reference positive PCT) and 0.25 (0.13-0.51) for more than 36 months infertility (reference 12-23 months). Semen analysis had no extra predictive power given the duration of infertility and the PCT. The PCT is an effective predictor of conception where defined female causes of infertility are absent and duration of infertility is less than 3 years. Once infertility is prolonged (beyond 3 years) the conception rate is low even with a positive test because a large proportion of couples remaining childless so long have true unexplained infertility. Use of the PCT will enable clinicians to allocate scarce, expensive and invasive resources effectively.

Factors associated with male infertility: a case-control study of 218 infertile and 240 fertile men

OBJECTIVE

To determine the likely risk factors, such as smoking and drinking habits, and occupational groups, for infertility in a group of infertile men with no known cause, compared with a group of fertile men; and to examine the effects of the semen parameters, such as volume, density, motility, viability and normal morphology, on fertility.

DESIGN

A case-control study.

SETTING

The department of obstetric and gynaecology of a tertiary general hospital.

PARTICIPANTS

Six hundred and forty consecutive male partners of couples trying to conceive were recruited from an infertility clinic. Of these, the cases comprised 218 men who had no known cause for their infertility. Two hundred and forty men whose wives were pregnant at the time of the study were recruited as controls.

RESULTS

The semen parameters (e.g. density, total sperm counts, motility, viability and normal morphology) of all cases were significantly poorer than that of the controls. The risk of infertility is associated with smoking (crude OR 2 x 82, 95% CI 1 x 93-4 x 13; adjusted OR 2 x 96; 95% CI 1 x 98-4 x 42). Technicians (adjusted OR 2 x 81; 95% CI 1 x 51-4 x 24) and professional, senior officials and managers were also at a greater risk of infertility (adjusted OR 2 x 36; 95% CI 1 x 26-4 x 40), compared with service and clerical workers. The significant factors predicting infertility were smoking, density of sperm, and viability of sperm. Smoking increased the odds of being infertile. Higher sperm counts and larger percentage of viable sperm decrease the odds of infertility. Based on the multiple logistic regression model, the odds ratio for infertility = (94 x 70) x (2 x 88(smoking)) X (0 x 29(logdensity)) X (0 x 95(viability)).

CONCLUSION

Smoking, density of sperm and the viability of sperm are significant predictors for infertility among men.

Accessing the fertilizing potential of cryopreserved sperm by its ability to maintain quality in a glycerol-free medium

Cryopreserved sperm is less fertile than fresh sperm; probably due to dependence of sperm to glycerol, a common cryoprotective agent. Few data suggest any correlations between standard semen analysis and fertility. To develop a reliable assay, the authors hypothesized that sperm that withstand the physiochemical stress induced by glycerol during cryopreservation may have higher fertility potential. They analyzed 55 cryopreserved semen samples for sperm concentration, percent motility and progressive motility after allowing thawed sperm to migrate into medium containing either 0 or 12% glycerol for 3 h. The smaller the difference in sperm quality between the two media, the higher the fertility potential of the spermatozoa. There was significant negative correlation between the difference in both percent sperm motility and percent progressive sperm motility in the two media and in vitro fertilization outcome. There was a significantly higher number of ejaculates fertilized oocytes at a rate of > or = 80% when the difference was 20% or less. This easy to use, inexpensive test may be an effective means to evaluate the potential performance of cryopreserved sperm to be utilized in assisted reproductive technologies.

The mean of sperm parameters in semen donations from the same donor. An important prognostic factor in insemination

We analysed 12,100 consecutive cycles of artificial insemination by donor spermatozoa in 1901 infertile couples. In our analysis, particular attention was given to finding an appropriate way of taking into account the respective effects of female and male factors on the pregnancy success rate and the level at which these factors act (cycle vs. woman and donation vs. donor). A total of 1213 pregnancies occurred. The pregnancy rate per cycle was lower as the age of the woman increased (p < 0.0001) and varied with the type of infertility: fecundity was higher (p = 0.03) in the case of azoospermia than of severe oligozoospermia. After taking into account these factors, significant unexplained variation in likelihood to conceive remained. A part of this heterogeneity was shown to be due to variation in fecundability between semen donors. In order to explain this heterogeneity between donors, compositional covariates were used, particularly the mean of results of the semen analysis performed for donations from the same donor. For each semen characteristic, the overall mean of the different donations of a donor was an important predictive factor of successful insemination: after taking into account all of the other factors, the odds ratios for an increase of 50 x 10(6)/mL spermatozoa, of a 20% increase in sperm motility and of a 2 point increase in the post-thaw quality index, were, respectively, 1.13, 1.37 and 1.56. After adjustment for these factors, the specific characteristics of each semen donation were no longer significantly predictive of successful insemination. This observation has a biological interpretation: sperm with low parameters but produced by a normally fertile man can have a satisfactory success rate.

Comparison of the sperm quality necessary for successful intrauterine insemination with World Health Organization threshold values for normal sperm

OBJECTIVE

To compare World Health Organization threshold values for normal sperm with the initial sperm quality necessary for successful IUI.

DESIGN

Retrospective study.

SETTING

Private fertility clinic.

PATIENT(S)

One thousand eight hundred forty-one couples undergoing 4,056 cycles of IUI.

INTERVENTION(S)

Intrauterine insemination.

MAIN OUTCOME MEASURE(S)

Relation of initial sperm quality to fecundity.

RESULT(S)

Progressive motility and total motile sperm count were the initial sperm characteristics most closely related to pregnancy on discriminant analysis. The per-cycle pregnancy rate averaged 11.1% during the first three IUI cycles. Pregnancy rates were > or = 8.2% per cycle when the initial sperm values were a concentration of > or = 5 X 10(6)/mL, a total count of > or = 10 X 10(6), progressive motility of > or = 30%, or a total motile sperm count of > or = 5 x 10(6). Minimal increases in fecundity occurred when initial values were greater than these threshold levels. The lowest initial values that resulted in pregnancy were a concentration of 2 x 10(6)/mL, a total count of 5 x 10(6). motility of 17%, and a total motile sperm count of 1.6 X 10(6). Pregnancy rates were <3.6% when initial values were between the threshold levels and the lowest levels.

CONCLUSION(S)

The sperm quality that is necessary for successful IUI is lower than World Health Organization threshold values for normal sperm. Intrauterine insemination is effective therapy for male factor infertility when initial sperm motility is > or = 30% and the total motile sperm count is > or = 5 X 10(6). When initial values are lower, IUI has little chance of success.

Infertility: from a personal to a public health problem

The inability to conceive a child is most often viewed as a private matter, but public health perspectives and skills can contribute greatly to our knowledge about infertility, and the development of effective and rational public policy for prevention, access to health care, and regulation of new technologies. We offer a primer of public health aspects of infertility in an effort to encourage the broad spectrum of public health professionals to become more knowledgeable about these topics and join in the national debate about preventive strategies, cost-benefit assessment, resource allocation, and ethics.

Human sperm head morphometric distribution and its influence on human fertility

OBJECTIVE

To study the distribution of live sperm head size in semen and sperm preparations as a predictor of fertility.

DESIGN

Prospective blind clinical trial.

SETTING

Academic tertiary referral center.

PATIENT(S)

One hundred fifty-five patients undergoing IVF treatment. Females with conditions negatively influencing fertilization were excluded.

INTERVENTION(S)

Morphometric analysis (head area, major axis, minor axis, and elongation ratio) of video images of sperm in semen and swim-up preparations used for IVF treatment was performed with a Hamilton-Thorne analyzer V 8.1 (Hamilton-Thorn Research, Beverly, MA).

MAIN OUTCOME MEASURE(S)

Oocyte fertilization.

RESULT(S)

Seventy-four percent of patients achieved fertilization. Fertilizers and nonfertilizers had different sperm head area distribution. The fertilizers had a significantly smaller interquartile range of sperm head area and of major axis in both semen and sperm preparation compared with the nonfertilizers. A subgroup of men who had fathered a child naturally had a more uniform sperm head area in semen with a significantly smaller median compared with those who failed to father a child naturally with their healthy female partner. We used multiple logistic regression applying forward stepwise selection of variables in building three predictive models of probability of fertilization.

CONCLUSION(S)

Successful IVF or history of fathering a child was associated with a more uniform sperm head area in semen and sperm preparation.

Relation between semen quality and fertility: a population-based study of 430 first-pregnancy planners

BACKGROUND

Semen analysis is part of the routine assessment of infertile couples. WHO defines a sperm concentration above 20x10(6) per mL seminal fluid as normal. We studied the association between semen quality and the probability of conception in a single menstrual cycle in Danish couples with no previous reproductive experience.

METHODS

In 1992-94, we invited 52,255 trades-union members aged 20-35 years, who lived with a partner and had no children to take part in the study; 430 couples agreed. The couples discontinued use of contraception, and were followed up for six menstrual cycles or until a pregnancy was verified within this period. Each man was asked to provide a semen sample at enrolment (which was analysed without freezing). Women kept a daily record of vaginal bleeding and sexual activity. The association between semen quality and likelihood of pregnancy was assessed by logistic regression, adjusted for sexual activity and female factors associated with low fertility.

RESULTS

There were 256 (59.5%) pregnancies among the 430 couples: 165 (65.0%) among those with a sperm concentration of 40x10(6)/mL or more and 84 (51.2%) among those with lower sperm concentrations. The probability of conception increased with increasing sperm concentration up to 40x10(6)/mL, but any higher sperm density was not associated with additional likelihood of pregnancy. The proportion of sperm with normal morphology was strongly related to likelihood of pregnancy independently of sperm concentration. Semen volume and motility were of limited value in pregnancy prediction.

INTERPRETATION

Our study suggests that the current WHO guidelines for normal semen quality should be used with caution. Some men with sperm counts above the lower limit of the normal range defined by WHO may in fact be subfertile.

Intrauterine insemination: is it an effective treatment for male factor infertility?

Results were collected from 11 studies comparing intrauterine insemination (IUI) with intracervical insemination (ICI) of frozen donor semen, 10 studies comparing IUI with timed natural intercourse (NI) or ICI in couples with semen defects and seven studies comparing ICI with NI or ICI in couples with unexplained infertility. IUI significantly increased the pregnancy rate relative to favourably timed ICI in donor insemination (DI) with frozen semen both with and without gonadotrophin stimulation of the female partner (odds ratios (95% confidence interval) 1.92 (1.02-3.61) and 2.63 (1.52-4.54) respectively). The benefit of IUI tended to be less when the pregnancy rate for ICI was high and IUI had no benefit with fresh donor semen. Overall IUI was of significant benefit in the male factor couples compared with NI-ICI (odds ratio 2.20 (1.43-3.39) and the advantage appeared to be maintained when comparison was confined to properly timed ICI although the odds ratios were not significantly greater than 1. IUI had no benefit relative to favourably timed NI-ICI for couples with unexplained infertility; an apparent advantage overall was produced by studies where NI was late. None of the studies on male factor used a sperm function test to define male subfertility and three only included couples with good mucus penetration by sperm. The range of semen defects defined was such that many couples would have had a good chance of conceiving naturally given a normal female partner but nevertheless the overall pregnancy rate (4.8%) was considerably less than in the unexplained group (11.6%), suggesting that some sperm dysfunction was present. We conclude that the available evidence suggests that IUI is valuable for DI with cryopreserved semen and for couples with mild to moderately impaired semen quality and postulate that it overcomes failure to fertilize due to impaired mucus penetration and poor survival in the female reproductive tract.

Clinical value of tests for assessing male infertility

The laboratory assessment of the male partner of an infertile couple is an important aspect of the overall investigation of that couple. The laboratory tests are designed essentially to determine whether (a) the semen samples contain adequate numbers of normal motile sperm, and the sperm are able (b) to migrate to the site of fertilization and (c) to fertilize oocytes. Within this framework, tests can be viewed as being either descriptive, in terms of describing the ejaculate and sperm, or assessing functional qualities of the sperm. Irrespective of the nature of the test, it must satisfy simple criteria, namely being reproducible and able to discriminate between the fertile and infertile populations reliably. External quality assurance programmes now exist for semen analysis and allied techniques to help laboratories to standardize their reporting and to identify the source of possible errors.

Relationship between etiological factors and total motile sperm count in 350 infertile patients

The prevalence of different etiologic factors has been evaluated in 350 male patients consulting the same physician in an urban, ambulatory setting for primary or secondary infertility of more than 1 year. Environmental factors such as alcohol or drugs represented 12% of the etiologies, acquired diseases such as varicocele and prostatitis 40%, congenital diseases and primary testicular failure 16.2%, idiopathic cases 19.4%, and abnormality of sperm transport 7.4%. The severity of sperm alterations in the different etiologic categories was evaluated by the total motile sperm count per ejaculate (TMS) (normal > 16). The TMS was less than 5 in classical causes of male infertility such as testicular failure, endocrinopathy, cancer, or antisperm antibodies. It was more than 10 in controversial causes of infertility such as varicocele, prostatis, chlamydial infections, and professional exposure to heat. After treatment, there was a nonsignificant increase of the TMS in the latter cases. In cases of azoospermia of pituitary origin, the TMS was normalized by a hormonal treatment. In some cases of azoospermia of possible obstructive origin, sperm appeared in the ejaculate after diclofenac treatment. The utility of andrological investigation and treatment is discussed.

Flow cytometric determination of spermatozoa binding monoclonal antibodies does not improve the prediction of fertility potential

In a previous publication the determination of binding of several monoclonal antibodies to human spermatozoa by flow cytometry was described in 223 patients. In normozoospermic samples the percentage of spermatozoa binding antibodies was higher than in samples with oligozoospermia. However, only weak correlations were found between the percentage of antibody binding spermatozoa and sperm count, motility and morphology. Thus the antibody binding may represent a property different from the classical parameters and might improve the prediction of fertility in the patients. A questionnaire was sent to all the patients inquiring about a conception in their female partners. One hundred and twenty one out of the 223 patients replied, 103 of whom we were able to evaluate. Forty five of them had induced a pregnancy in their partners. The mean values of sperm count, motility and morphological normal cells, as well as the percentages of cells that bound antibodies, were significantly higher in the group of men whose partners became pregnant, than in those who had not achieved conception. The differences, however, were only marginal. We conclude from our results that the determination of the percentage of spermatozoa binding the monoclonal antibodies used in our study is not likely to improve the prediction of conception probability.

Application of the hypo-osmotic swelling test to spermatozoa prepared by swim-up and discontinuous Percoll separation

The quality of spermatozoa prepared by washing and swim-up or by discontinuous Percoll centrifugation, was compared by applying the hypo-osmotic swelling (HOS) test to semen samples from 116 men of infertile couples. The HOS test performed on 95 normal semen samples showed that the percentage of swollen spermatozoa separated by both techniques was significantly higher than in the initial ejaculate (p < 0.001). The percentage of HOS-positive spermatozoa separated by the Percoll gradient technique was significantly higher than that separated by the swim-up technique (p < 0.001). On the contrary, in 21 abnormal semen samples, there was no significant difference in the percentage of spermatozoa which were positive in the HOS test between the Percoll gradient and the swim-up technique (p = 0.44). It is suggested that the Percoll gradient technique appears to be preferable to the swim-up technique when semen parameters are normal, but there is no significant difference between these two technique in abnormal semen.

Computer-aided semen analysis variables as predictors of male fertility potential

A computer-aided semen analysis (CASA) was used to allow digitizing the motion of the spermatozoon. This procedure allows an objective means of judging semen quality, especially the translational movements of spermatozoa. Forty-three couples were included in the study. The average age of the male was 35.5 +/- 4.7 years and that of the female was 32.7 +/- 4.7 years. The average duration of infertility was 3.8 +/- 2.3 years. Using multiple linear regression analysis of 26 prognostic variables, a cluster of 8 variables significantly predicted pregnancy maximally. The 8 variables and the resultant multiple correlation coefficients were used to generate a multiple regression equation which allowed the correct separation of the population into fertile and infertile couples. The mean pregnancy predictor values of the fertile and infertile populations were significantly different using the analysis of variance.

Predictive power of sperm motion analysis in in vitro fertilization

The correlation between sperm motion characteristics and in vitro fertilization was studied in 160 cycles, divided in two groups: those with male subfertility (N=42) and those with tubal disease (N=118). The group with male subfertility showed inferior performance, as indicated by a lower fertilization rate per oocyte (40% versus 66%) and per pick-up cycle (67% versus 93%). These two groups exhibited no significant difference in the mean sperm velocity, linearity, amplitude of lateral head displacement, and beat cross frequency in the pre swim-up and post swim-up specimens. The two groups differed in pre and post swim-up sperm motility, pre and post swim-up concentration, pre swim-up cumulative velocity at 110 to 140 Amicrom/sec and post swim-up cumulative velocity at 130 microm/sec. Logistic regression analysis was used to determine those variables that would predict fertilization; pre swim-up count and post swim-up motility proved to be the significant determinants. The results indicate that assessment of motion by automated semen analyzers does not supplement conventional semen analysis in the ability to predict fertilization.

Evaluation of different sperm function tests as screening methods for male fertilization potential--the value of the sperm migration test

OBJECTIVE

To assess the value of different sperm function screening tests in predicting fertilization.

DESIGN

Prospective study.

SETTING

Academic tertiary referral center for fertility treatment.

PATIENTS

Ninety-five couples attending for initial screening and IVF-ET. Only cycles where three or more grade I oocytes were collected were included, and patients with endometriosis were excluded.

INTERVENTIONS

Each patient had a standard semen analysis, cervical mucus (CM) penetration test, hypo-osmotic swelling test, and sperm migration test performed between 4 and 8 weeks before IVF-ET.

MAIN OUTCOME MEASURES

The correlation between sperm function test results and the percentage of fertilized oocytes and the power of the tests to predict fertilization.

RESULTS

The sperm migration test correlated highly with fertilization rate (r = 0.62) and was most useful in identifying the group of patients likely to achieve fertilization (Odds ratio [OR] 0.07, confidence interval [CI] 0.02 to 0.2). The CM penetration test showed a moderate correlation with fertilization rate (r = 0.45) and some predictive power (OR 0.37, CI 0.13 to 1.00). Sperm concentration, but not motility or normal morphology, showed slight correlation with fertilization rate (r = 0.28) but the combination of normal semen parameters did not distinguish patients likely to achieve fertilization (OR 1.51, CI 0.62 to 3.65). The hypo-osmotic swelling test did not correlate with fertilization rate (r = 0.21).

CONCLUSIONS

This study evaluated the predictive power of several simple tests available for use in most laboratories as screening tests of sperm fertilization potential. Apart from sperm concentration, normal traditional semen characteristics were of little clinical benefit. The hypo-osmotic swelling test had no predictive power. The CM penetration test correlated with fertilization rate but might be difficult to perform routinely as a continuous supply of suitable CM would be required. The sperm migration test proved to be the best discriminator of sperm fertilization potential and should be considered as a first level screening test in the assessment of male fertility.

Sperm function and its manipulation for microassisted fertilization

Comprehension of the intricate complexities of sperm function is clearly crucial to the success of attempts to manipulate it for the purposes of assisted conception. This is particularly important when considering various procedures for microassisted fertilization since these bypass critical physiological events that are mandatory for normal fertilization, to varying degrees. Methylxanthine derivatives such as pentoxifylline are useful agents for the management of oligoasthenozoospermic patients. This is particularly so for procedures such as SUZI where adequate motility of spermatozoa injected into the perivitelline space is crucial for fusion with the vitelline membrane to achieve fertilization. The generation of minute concentrations of reactive oxygen species in vitro may prove to be a valuable technique in this respect, in the light of recent evidence for their involvement in capacitation and hyperactivation. Induction of the acrosome reaction by non-invasive, non-toxic agents should markedly improve success rates for microassisted fertilization. Acrosin appears to play a central role in this and, therefore, it would seem prudent to monitor levels of acrosin activity in samples of spermatozoa used in assisted conception procedures. With respect to microassisted fertilization, the potential to select recently acrosome-reacted spermatozoa coated by activated acrosin promises to be a major improvement. Current methods employed for determination of the fertilization potential of spermatozoa are clearly inadequate (Polansky and Lamb, 1988; Aitken, 1990). In fact, the prevailing evidence suggests that no single parameter of sperm function reflects this potential (Zaneveld and Jeyendran, 1988). Therefore, we have both a scientific and a moral responsibility to investigate these processes further. Subsequently, we should be in a position to identify individual gametes with the potential for fertilization and so utilize procedures that result in maximal fertilization rates with minimal risk of polyploidy or abnormality.