Diagnostic value of sperm function tests and routine semen analyses in fertile and infertile men

The hypo-osmotic swelling test: Is it a sperm vitality or a viability assay?

The first two editions of the World Health Organization laboratory manual described the determination of live spermatozoa by a dye exclusion method as a sperm "viability" test, whereas subsequent editions classified it as a "vitality" test, without providing an explanation for the reclassification. Additionally, the hypo-osmotic swelling (HOS) test, which assesses the functional integrity of the human sperm membrane, was placed in the same category as the dye exclusion test. Although the two terms might seem synonymous, the term "vitality" merely means "alive," whereas "viability" assesses qualities or physiological functions of a living entity. After comparing the morphological, physiological, and clinical findings obtained from dye exclusion testing vs. the HOS test, we conclude that the HOS test should be classified as a viability test, not merely as a vitality test.

A Randomized Trial to Evaluate the Effects of Folic Acid and Zinc Supplementation on Male Fertility and Livebirth: Design and Baseline Characteristics

The Folic Acid and Zinc Supplementation Trial (FAZST) was a multicenter, double-blind, block-randomized, placebo-controlled trial to determine whether folic acid and zinc supplementation in men improves semen quality and increases livebirth rate among couples seeking infertility treatment (2013-2017). Eligible men were aged 18 years or older with female partners aged 18-45 years, seeking infertility treatment. Men were randomized (1:1) to 5 mg folic acid and 30 mg elemental zinc daily or matching placebo for 6 months. Randomization was stratified by site and intended infertility treatment (in vitro fertilization (IVF), non-IVF/study site, and non-IVF/outside clinic). Follow-up of men continued for 6 months, and female partners were passively followed for a minimum of 9 months. Women who conceived were followed throughout pregnancy. Overall, 2,370 men were randomized during 2013-2017 (1,185 folic acid and zinc, 1,185 placebo); they had a mean age of 33 years and body mass index (weight (kg)/height (m)2) of 29.8. Most participants were white (82%), well educated (83% with some college), and employed (72%). Participant characteristics were balanced across intervention arms. Study visits were completed by 89%, 77%, and 75% of men at months 2, 4, and 6, respectively. Here we describe the study design, recruitment, data collection, lessons learned, and baseline participant characteristics.

A data-driven search for semen-related phenotypes in conception delay

Sperm count, morphology, and motility have been reported to be predictive of pregnancy, although with equivocal basis prompting some authors to question the prognostic value of semen analysis. To assess the utility of including semen quality data in predicting conception delay or requiring >6 cycles to become pregnant (referred to as conception delay), we utilized novel data-driven analytic techniques in a pre-conception cohort of couples prospectively followed up for time-to-pregnancy. The study cohort comprised 402 (80%) male partners who provided semen samples and had time-to-pregnancy information. Female partners used home pregnancy tests and recorded results in daily journals. Odds ratios (OR), false discovery rates, and 95% confidence intervals (CIs) for conception delay (time-to-pregnancy > 6 cycles) were estimated for 40 semen quality phenotypes comprising 35 semen quality endpoints and 5 closely related fecundity determinants (body mass index, time of contraception, lipids, cotinine and seminal white blood cells). Both traditional and strict sperm phenotype measures were associated with lower odds of conception delay. Specifically, for an increase in percent morphologically normal spermatozoa using traditional methods, we observed a 40% decrease in conception delay (OR = 0.6, 95% CI = 0.50, 0.81; p = 0.0003). Similarly, for an increase in strict criteria, we observed a 30% decrease in odds for conception delay (OR = 0.7, 95% CI = 0.52, 0.83; p = 0.001). On the other hand, an increase in percent coiled tail spermatozoa was associated with a 40% increase in the odds for conception delay (OR = 1.4, 95% CI = 1.12, 1.75; p = 0.003). However, our findings suggest that semen phenotypes have little predictive value of conception delay (area under the curve of 73%). In a multivariate model containing significant semen factors and traditional risk factors (i.e. age, body mass index, cotinine and ever having fathered a pregnancy), there was a modest improvement in prediction of conception delay (16% increase in area under the curve, p < 0.0002).

Urinary Phytoestrogens Are Associated with Subtle Indicators of Semen Quality among Male Partners of Couples Desiring Pregnancy

BACKGROUND

Phytoestrogens have been associated with subtle hormonal changes, although effects on male fecundity are largely unknown.

OBJECTIVE

We evaluated associations between male urinary phytoestrogen (isoflavone and lignan) concentrations and semen quality.

METHODS

This study was a prospective cohort study of 501 male partners of couples desiring pregnancy and discontinuing contraception. Each participant provided up to 2 semen samples that were analyzed for 35 semen quality endpoints the following day. Linear mixed-effects models were used to estimate associations between baseline urinary phytoestrogen concentrations and semen quality parameters, adjusted for age, body mass index (BMI), research site, and serum lipid and cotinine concentrations.

RESULTS

Most associations between urinary phytoestrogens and semen quality parameters were null. However, select individual phytoestrogens were associated with semen quality parameters, with associations dependent on the class of phytoestrogens and modified by BMI. Specifically, genistein and daidzein were associated with a lower percentage of normal sperm and increased abnormalities in semen morphology, with reduced associations observed as BMI increased (P < 0.05) [percentages (95% CIs) of normal morphology by WHO traditional criteria: genistein, main effect: -5.61% (-9.42%, -1.79%); interaction: 0.19% (0.06%, 0.31%) per log unit increase; daidzein, main effect: -5.35% (-9.36%, -1.34%); interaction: 0.18% (0.05%, 0.32%) per log unit increase]. Enterolactone was associated with fewer abnormalities in semen morphometry and morphology and decreased DNA fragmentation, with reduced associations observed as BMI increased (P < 0.05) [percentages (95% CIs) of abnormalities in the neck and midpiece: enterolactone, main effect: -3.35% (-6.51%, -0.19%); interaction: 0.11% (0.01%, 0.21%) per log unit increase].

CONCLUSIONS

These results suggest that male urinary phytoestrogen concentrations characteristic of the US population may be associated with subtle indicators of male fecundity and semen quality but were not associated with couple fecundity.

Benzo[a]pyrene effects on reproductive endpoints in Fundulus heteroclitus

Benzo[a]pyrene (BaP) is a polycyclic aromatic hydrocarbon (PAH) that has been implicated in modulating aromatase enzyme function with the potential to interrupt normal reproductive function. The aim of this study was to use a fish model, Fundulus heteroclitus, to assess whether BaP exposure adversely impacts reproduction. Adult fish were exposed to waterborne BaP nominal concentrations of (0, 1, or 10 μg/l) for 28 days. Males and females were combined for the second half of the exposure (days 14-28) in order to quantitate egg production and fertilization success. Egg fertilization and subsequent hatching success of F1 embryos was significantly decreased by the high dose of BaP. In males, both gonad weight and plasma testosterone concentrations were significantly reduced compared to controls by 10 μg/l BaP. Histopathological examination of testes including spermatogonia, spermatocyte and spermatid cyst areas, percentage of cysts per phase, and area of spermatozoa per seminiferous tubule were not significantly affected. Other biomarkers, including male liver weight, liver vitellogenin (vtg) mRNA expression and sperm concentrations, were also not affected. In females, estradiol concentrations were significantly reduced after BaP exposure, but egg production, gonad weight, liver weight, vtg expression and oocyte maturation were not altered. Steroid concentrations in Fundulus larvae from exposed parents at 1 and 3 weeks posthatch were not significantly changed. BaP exposure at these environmentally relevant concentrations caused negative alterations particularly in male fish to both biochemical and phenotypic biomarkers associated with reproduction and multigenerational embryo survival.

Semen quality and time to pregnancy: the Longitudinal Investigation of Fertility and the Environment Study

OBJECTIVE

To assess semen parameters and couple fecundity as measured by time to pregnancy (TTP).

DESIGN

Observational prospective cohort with longitudinal measurement of TTP.

SETTING

Sixteen Michigan/Texas counties.

PATIENT(S)

A total of 501 couples discontinuing contraception were followed for 1 year while trying to conceive; 473 men (94%) provided one semen sample, and 80% provided two samples.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Using prospectively measured TTP, fecundability odds ratios (FORs) and 95% confidence intervals (CIs) were estimated for 36 individual semen quality parameters accounting for repeated semen samples, time off contraception, abstinence, enrollment site, and couples' ages, body mass indices, and serum cotinine concentrations.

RESULT(S)

In adjusted models, semen quality parameters were associated with significantly shorter TTP as measured by FORs >1: percent motility, strict and traditional morphology, sperm head width, elongation factor, and acrosome area. Significantly longer TTPs or FORs <1 were observed for morphologic categories amorphous and round sperm heads and neck/midpiece abnormalities. No semen quality parameters achieved significance when simultaneously modeling all other significant semen parameters and covariates, except for percent coiled tail when adjusting for sperm concentration (FOR 0.99; 95% CI 0.99-1.00). Male age was consistently associated with reduced couple fecundity (FOR 0.96; 95% CI 0.93-0.99), reflecting a longer TTP across all combined models. Female but not male body mass index also conferred a longer TTP (FOR 0.98; 95% CI 0.96-0.99).

CONCLUSION(S)

Several semen measures were significantly associated with TTP when modeled individually but not jointly and in the context of relevant couple-based covariates.

Male fertility and reduction in semen parameters: a single tertiary-care center experience

Background. Infertility is both a clinical and a public problem, affecting the life of the couple, the healthcare services, and social environment. Standard semen analysis is the surrogate measure of male fertility in clinical practice. Objective. To provide information about the relationship between semen parameters and spontaneous conception. Methods. We evaluated retrospectively 453 pregnancies that occurred among 2935 infertile couples evaluated at an infertility clinic of a tertiary-care university hospital, between 2004 and 2009. Results. Normal semen analysis was present only in 158 patients; 295 subfertile patients showed alterations in at least one seminal parameter. A reduction in all seminal parameters was observed in 41 patients. Etiological causes of male infertility were identified in 314 patients. Conclusion. Our data highlights the possibility of a spontaneous conception with semen parameters below WHO reference values. Therefore, we support the importance of defining reference values on a population of fertile men. Finally, we analyzed the related ethical issues.

Decreasing sperm quality: a global problem?

BACKGROUND

Carlsen and coworkers (1992) reviewed 61 heterogeneous observational studies on semen quality published between 1938 and 1990. This review indicates that mean sperm density decreased significantly between 1940 and 1990. An extended meta-analysis with 101 studies confirmed a decline in sperm density for the period from 1934 to 1996 (2000). The key message of the meta-analyses is that sperm counts have decreased globally by about 50% over the past decades. This assessment has been questioned.

DISCUSSION

A major methodological problem of the meta-analysis is the use of data collected in different countries, at different times, on different populations and with different methods of semen analysis. Furthermore, the results of studies concerning semen analysis are frequently biased e.g. by selection criteria of volunteers. In most studies on human semen characteristics the populations under study are insufficiently defined and the study participants are not a representative population sample. The incidence of testicular cancer has increased in Caucasian men worldwide. The investigation of common risk factors for male reproductive disorders requires well designed epidemiological studies and the collection of individual data.

SUMMARY

Former meta-analyses of sperm count data show a global downward trend. This conclusion should be interpreted with caution. The included studies are of great heterogeneity due to geographical and/or ethnical variation, different study designs and different methodological standards. Population-based prospective studies are needed to investigate secular trends in male reproductive disorders.

Canine fresh and cryopreserved semen evaluation

There is little doubt that objective assessment of multiple parameters related to the functional and morphological characteristics of spermatozoa, increase the predictability of the fertilizing potential of a semen sample. Conventional microscopic methods for sperm evaluation in combination with the more objective computer-assisted sperm motility and morphology analyzers and flow cytometry, have allowed investigators to obtain precise information about the morphofunctional status of spermatozoa, which already has resulted in a better understanding of sperm biology and of some of the mechanisms involved in sperm cryoinjury. In addition, assays based on in vitro fertilization provide valuable information about the functional ability of spermatozoa when interacting with the oocyte. Although objective methods for dog sperm evaluation are available for many researchers, considerable effort has still to be invested in order to standardize physiological sperm parameters for the results to be interpretable under unified criteria. In the present paper some of the classical and new methods currently used for dog sperm evaluation are reviewed, though not exhaustively, covering some aspects of the sperm cell that are useful in estimating its functional ability.

Use of the Sperm-Class Analyser for objective assessment of human sperm morphology

The Sperm-Class Analyser was validated for assessing morphometric parameters of the head and midpiece of unwashed and washed human ejaculated spermatozoa from volunteers providing a wide range of semen quality. A higher proportion of sperm could be assessed (86% fresh semen and 75% washed sperm) if Hemacolor staining was used rather than DiffQuik (80 and 73%) or Papanicolaou (78 and 68%). Different stains employed different fixatives and the area, length, width and perimeter of the sperm head was significantly larger for washed sperm stained by Hemacolor and DiffQuik. Acrosomal area ranged from 48 to 51% of the sperm head area and this percentage was larger for washed sperm stained with DiffQuik. Sperm at the end of the slide, distant from the initial semen droplet, were larger in area and perimeter than those at that site or in the middle. The high precision and reproducibility of the equipment required assessing only 50 sperm on the slide. Far greater variation was found in head width, relative acrosomal area and midpiece width between different slides prepared from the same ejaculate, highlighting the inherent variability within the ejaculate and smear preparation, and requiring more than one slide to be assessed.

Some aspects relating to the evaluation of the effects of chemicals on male fertility

Reviews and studies on individual compounds were analyzed as to the suitability of different study designs and endpoints for detecting adverse effects of chemicals on male reproduction in animal species. Of the endpoints investigated, the most sensitive proved to be histopathology of the testes. Using refined histopathology, effects could be detected with a high degree of sensitivity as early as 4 weeks after treatment. Other sensitive endpoints were the weights of reproductive organs, including accessory glands, i.e., testis, epididymis, prostate, and of the seminal vesicle, as well as sperm parameters such as sperm count, sperm morphology, and sperm motility. Sperm motility was found to be in some cases more sensitive than histopathology. The above parameters showed a higher sensitivity than fertility parameters. In fact, in most cases, not only one but several endpoints were affected. Continuous breeding studies and 90-day studies with additional measurements of sperm parameters were similarly effective in detecting compounds which affect male fertility. Interspecies extrapolation factors (IEFs) have been derived for the most sensitive endpoints in laboratory animals. If the calculation is based on caloric demand and a sensitive endpoint of reproductive toxicity, many IEFs tend to be about 1, indicating that humans are generally not more susceptible to reproductive toxicants than laboratory animals. With respect to hazard identification, it is possible to detect adverse effects on male reproduction in a standard subacute study with concentrations that produce significant general toxicity. If effects are found, for the risk assessment the NOAEL has to be determined by testing specific sensitive parameters as specified above.

Some semen abnormalities may cause infertility by impairing implantation rather than fertilization

The hypo-osmotic swelling (HOS) test measures the functional integrity of the sperm membrane. Although, the sperm membrane is essential for the fertilization of oocytes, several clinical studies suggest that abnormally low HOS test scores do not predict poor or failed fertilization in human in-vitro fertilization trials. However, in-vivo and in-vitro studies clearly demonstrate that a low HOS score is associated with poor pregnancy rates suggesting this sperm defect causes implantation problems rather than fertilization problems. The problem of implantation could be caused by the supernumerary sperm attached to the zona pellucida. Supporting evidence for this theory was demonstrated by finding high pregnancy and implantation rates despite low HOS scores following intracytoplasmic sperm injection which avoids the presence of supernumerary sperm on the zona pellucida. These data thus support theories that some sperm abnormalities may reduce fertility potential by causing implantation disorders rather than problems with fertilization.

Chromatin status in human ejaculated spermatozoa from infertile patients and relationship to seminal parameters

The aim of this study was to evaluate the chromatin status in different groups of patients. Five groups of men were selected: pre-vasectomy; male factor infertility; varicocele; immunological male infertility; and idiopathic infertility. Chromatin status was evaluated using flow cytometry after staining the DNA with the fluorochrome propidium iodide. Differences were observed in the state of sperm chromatin between the male factor and varicocele groups with respect to the others. These two groups presented poorer quality chromatin, as evidenced fundamentally by a lower degree of condensation. These deficiencies in chromatin status were usually accompanied by alterations in the other standard parameters of semen analysis. Individuals who are infertile due to male factor and those presenting varicocele have spermatozoa with less condensed chromatin which might, in part, explain their sterility.

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.

Infertility. A clinical guide for the internist

Infertility is a common condition that internists practicing primary care may increasingly encounter. Abnormal male semen parameters, ovulation disorders, and tubal dysfunction account for most cases of infertility. By performing a complete initial evaluation and through appropriate and timely referral, internists can contribute to the care and improve outcomes for couples with this condition (Table 9).

Relationship between seminal LDH-C4 and spermatozoa with acrosome anomalies

Lactate dehydrogenase C4 (LDH-C4), the specific isozyme of LDH produced by germ cells, was assessed in the seminal plasma of 55 patients to test a potential link between LDH-C4 and the count per ml of spermatozoa with acrosome anomalies. A simple regression curve shows a statistically significant positive correlation between seminal LDH-C4 concentrations and count per ml of spermatozoa with acrosome anomalies (r = + 0.640, P < 0.0001). No correlation was found between seminal LDH-C4 concentrations and sperm motility. Though seminal LDH-C4 thus seems to be a poor indirect marker of energy produced by spermatozoa, in contrast, this LDH isozyme may be a useful indirect marker of acrosome anomalies.

Hypo-osmotic swelling test: a reliable screening assay for routine semen specimen quality screening

We investigated whether the hypo-osmotic swelling (HOS) test is a reliable screening method for routine semen specimen quality screening. Of 159 male patients, 171 semen samples were investigated using the HOS test as well as routine semen specimen screening used in our clinic. There was a significant correlation between the HOS test and most semen parameters. There was no significant correlation between the HOS test and the percentage of morphologically normal spermatozoa in the initial semen sample. The HOS test is a reliable screening method for routine semen quality screening.

Predicting the success of in vitro fertilization: conventional semen analysis compared to the hamster ova penetration test

In vitro fertilization has been advocated as a possible treatment for male factor infertility. Using data collected on 154 men, conventional semen analysis and the hamster ova penetration test are compared with respect to their power in predicting the success of assisted conception. As performing the hamster test is more expensive than the semen analysis, we also investigate a combined strategy. It performs better than the discrimination based solely on the semen parameters, but does not lead to an improvement over the overall discriminatory power obtained from the hamster test alone.

Association between human in vitro fertilization rate and pregnancy outcome: a possible involvement of spermatozoal quality in subsequent embryonic viability

A conventional view of mammalian fertilization is that the active component of the process: the spermatozoon, by virtue of its progressive motility and acrosomal enzymes, penetrates an otherwise passive oocyte. This concept has placed bias on spermatozoal normality as largely determining the outcome of fertilization; once this has been achieved then the contribution of the spermatozoon is often forgotten, and attention switches to the maternally derived "blue-print" for early embryonic development. Paternal genomic contribution is known to start at the eight-cell stage in the human, but this is usually after the time when early cleavage stage (2 to 8-cell stage) embryos are replaced in human assisted reproductive technologies (ART) procedures such as in vitro fertilization and embryo transfer (IVF-ET). Hence, fundamental abnormal contributions to embryogenesis derived from the fertilizing spermatozoon have often been ignored. Human IVF-ET has permitted far greater powers of analysis of the fertilization event, and fertilization success appears to be determined in such a system by three main factors: spermatozoal quality, oocyte quality, and quality of in vitro culture conditions (the gamete environment). If the second two factors are more carefully controlled than the first, as is the usual emphasis in routine human IVF practice, then any large variation in fertilization rates that are also significantly related to embryonic viability and ultimately pregnancy outcome, may be thought to be more directly associated with original quality of the fertilizing spermatozoon. An analysis of results of 758 IVF cases provides preliminary evidence to show that there is a close association between human in vitro fertilization rate and subsequent embryo viability following replacement. In accepting this hypothesis as a possibility, we should drastically change our attitude from one of the spermatozoon as a robust, simple initiator of embryonic development, and embrace the idea of the vulnerability of such germ cells both during and after their production, and how detrimental influences on this might profoundly affect embryogenesis after successful fertilization.

Seminal leucocyte subpopulations and sperm function in fertile and infertile Chinese men

The level of seminal leucocytes and the prevalence of leucocytospermia was determined in a group of fertile and infertile southern Chinese men in Hong Kong. Sixteen normal fertile semen donors and 49 men with male factor infertility were studied prospectively. None had antisperm antibodies and past or present evidence of genital tract infection. Seminal leucocytes and their subsets were analysed using monoclonal antibodies and an immunocytochemical alkaline phosphatase-anti-alkaline phosphatase conjugate technique. Seminal leucocytes were detectable in 94% and 86% of the fertile and infertile men respectively, with the predominant subset being granulocytes. Leucocytospermia (> 1 x 10(6) leucocytes/ml) was found in only one of the 49 (2%) infertile men without clinical evidence of genito-urinary infection. Inverse correlations were observed between (1) the percentage of spermatozoa with normal morphology and the number of T-helper/inducer cells, (2) the linearity of sperm movement and the number of T-lymphocytes. In conclusion, the level of seminal leucocytes and the prevalence of leucocytospermia is low in infertile Chinese subjects. The effect of seminal leucocytes on sperm function in these subjects needs further evaluation.

Fertility prognosis for infertile couples

OBJECTIVE

To develop a fertility prognosis model for infertile couples.

DESIGN

Prospective follow-up study.

PARTICIPANTS

In the period November 30, 1977 to June 1, 1985, 321 consecutive couples were investigated for infertility at Hvidovre University Hospital. Investigation of the female included detection of ovarian, cervical, and anatomic disorders, whereas in the male semen analysis and sperm penetration test (P-test) were performed. Altogether, 108 couples (34%) conceived, whereas 213 (66%) were observed for an average of 2.3 years without having achieved pregnancy.

MAIN OUTCOME MEASURE

The Cox regression model was used to predict the time required to conceive based on informations provided by fertility investigations.

RESULTS

Three of 16 prognostic variables (the period of infertility, the female infertility factor, and the P-test) possess significant prognostic information. The period of infertility and the P-test are best scored as continuous variables, whereas the female infertility factor are best categorized in four classes, i.e., normal, ovulation or cervical disorder, anatomic disorder, or a combination of disorders.

CONCLUSIONS

The three prognostic variables are combined to form a prognostic index that predicts the fecundability of the individual infertile couple.

The hypoosmotic swelling test: an update

The hypoosmotic swelling (HOS) test is a relatively new assay used to evaluate the functional integrity of the sperm's plasma membrane. In fact, more studies have been published on the applicability of the HOS test than any other new sperm indicator. The assay is based on the fact that fluid transport occurs across an intact cell membrane under hypoosmotic conditions until equilibrium is reached. Due to the influx of fluid, the cell will expand and bulge, especially in the tail, and this change can be readily observed with a phase contrast microscope. Earlier studies have yielded some confusion regarding the interpretation of the data. This review is an attempt to clarify and update the usefulness of the HOS test as a tool to evaluate the sperm function.

Evaluation of the hypo-osmotic swelling test in relation with advanced methods of semen analysis

The hypo-osmotic swelling test was claimed to assess an independent functional characteristic of human spermatozoa bearing relevance to their fertilizing capacity. To test this claim, we have studied the relationship between the result of the hypo-osmotic swelling test with that of conventional semen analysis and sperm motility patterns, the semen content of adenosine triphosphate, the staining pattern to acidified aniline blue, and the zona-free hamster oocyte test. The result of the HOS test is significantly correlated with all sperm characteristics except for the aniline blue stainability and the hamster oocyte test. The capacity of spermatozoa to react in a hypo-osmotic environment expresses the same functional information as the viability test using eosine staining. It is concluded that the hypo-osmotic swelling test does not add relevant information to that obtained by routine sperm analysis with regards to the fertilizing potential of semen.

Evaluation of testicular function

The evaluation of testicular function is based primarily on a detailed medical history, a careful physical examination, basal measurements of FSH, LH and testosterone and a routine semen analysis. In a patient with androgen deficiency, the diagnosis can often be made with these basic tests. The clinician will then decide on other investigations to localize the organic lesion and to plan further treatment for the patient. Sperm function tests are often performed in patients presenting with infertility. These newer tests may help to delineate the abnormality of the spermatozoa at each stage during the achievement of fertilizing capacity such as adequate forward motility, penetration of cervical mucus, acrosome reaction, development of hyperactivated motility, binding to the zona pellucida, and fusion with the oocyte. Currently, many of these sperm function tests depend on cumbersome bioassays with many limiting factors contributing to their availability, accuracy and precision. The development of biochemical tests as markers of sperm function may allow more precise definition of sperm functional abnormalities. With the continued improvement of computer-aided sperm analysis, objective motion parameter measurements are possible and morphological assessment are being developed. These newer objective methods of semen analysis have to be shown to be valuable in the clinical assessment of patients with testicular dysfunction.

Reappraisal of the hypo-osmotic swelling test to improve assessment of seminal fertility status

The hypo-osmotic swelling (HOS) test has been proposed as a useful assay for evaluation of the functional competence of the human sperm membranes. To assess this further, the HOS-test was evaluated in 187 semen samples collected from fertile men and from male patients consulting for infertility. These samples were classified as normal, oligo-, astheno- or oligoasthenozoospermic on the basis of their standard semen variables. The percentage of total sperm tail swelling and of sperm exhibiting different tail swelling patterns was recorded. In the fertile men and in the group of patients with normal semen variables, significantly more (P less than 0.001) HOS-reactive sperm were observed after hypo-osmotic treatment in comparison with those groups exhibiting abnormal semen parameters. Swelling of the sperm in a hypo-osmotic medium was highly correlated with both progressive motility (r = 0.62, P less than 0.001) and sperm viability (r = 0.65, P less than 0.001). A weak positive correlation was also observed between sperm swelling and sperm morphological features (r = 0.31, P less than 0.005) and between sperm swelling and sperm concentration (r = 0.31, P less than 0.005). No significant correlation was observed between sperm swelling and in-vitro sperm fertilizing capacity as assessed by the zona-free hamster oocyte penetration assay. However the majority of the semen samples (87.3%) showing a normal penetration rate (greater than or equal to 10%) also exhibited a 60% (or higher) reaction in the HOS-test.(ABSTRACT TRUNCATED AT 250 WORDS)

Computer-assisted assessment of human sperm morphology: usefulness in predicting fertilizing capacity of human spermatozoa

OBJECTIVE

The usefulness of sperm morphology to predict the outcome of human sperm fertilizing capacity was examined.

DESIGN, SETTING, PATIENTS

Semen samples from 50 male patients attending the infertility clinic of a tertiary referral institution were studied.

MAIN OUTCOME MEASURES

Sperm morphology was classified both by visual assessment and computer-assisted image analysis. In addition, morphometric analysis of the spermatozoa was measured by the morphologizer. Multivariate discriminant analysis was used to evaluate the usefulness of these morphology parameters for predicting the outcome of the zona-free hamster oocyte sperm penetration assay.

RESULTS

The manually derived percent of spermatozoa with normal and small head were selected to be of discriminating value in predicting the outcome of the zona-free hamster oocyte penetration test. The accuracy of correctly classifying the outcome of zona-free hamster oocyte penetration test by these two parameters in combination was 84%, whereas assessment of sperm morphology with morphometric analysis by the morphologizer selected a total of eight variables, which together predicted sperm fertilizing capacity with 74% accuracy. Addition of the morphologizer-derived parameters to those derived manually did not significantly improve the predictive value.

CONCLUSION

We conclude that the results of the zona-free hamster egg penetration test could be predicted using manual assessment of sperm morphology and computer-assisted morphometric analysis did not add further information.

High ejaculate volume: a distinct entity?

In this study clinical, andrological and endocrinological data of a group of 101 patients with ejaculate volume of at least 8.0 ml are compared with data of 100 consecutive patients attending our infertility clinic. Within both groups correlations between different parameters are observed. Between both groups a significant difference in total sperm output is noted suggesting a 'dilution oligozoospermia' in the high ejaculate volume group. We suggest that, in order to avoid a falsely unfavourable fertility prognosis for those patients, total sperm output should be considered rather than sperm density. From the point of view of nomenclature, the term 'relative oligozoospermia' seems justified in cases with very high ejaculate volumes.

The diagnostic value of seminal adenosine triphosphate (ATP) in an in vitro fertilization (IVF) program

The level of adenosine triphosphate (ATP) was quantitated in semen samples used for in vitro fertilization of human oocytes. Seminal ATP level correlated with the concentration and percentage motility of spermatozoa but not with the in vitro fertilization rate of human oocytes. Seminal ATP measurement appears to have little diagnostic value in predicting the fertilizing capacity of spermatozoa as evaluated by the multivariate stepwise discriminant analysis.

Morphology of seminal and swim-up spermatozoa and the outcome of in vitro fertilization and embryo transfer

Tubal infertility was treated by in vitro fertilization-embryo transfer (IVF-ET) in 112 couples. Twenty-eight pregnancies were obtained in 140 treatment cycles. Couples are accepted for treatment in our IVF-ET programme if previous semen samples fulfil the inclusion criteria: ejaculate volume greater than 1.5 ml, concentration of spermatozoa greater than 15 x 10(6) ml-1, greater than 40% motile spermatozoa, and greater than 25% spermatozoa with normal morphology. In order to determine to which extent IVF-ET treatment results are influenced by sperm morphology, within this selected group of patients, we have retrospectively analysed the data from both original semen samples and swim-up preparations. The sperm morphology was not related to the outcome of treatment in terms of fertilization (ovum cleavage rate), early embryo development, or pregnancy. Nor was any relationship detected between early embryo development or pregnancy and the degree of improvement in morphology resulting from the swim-up procedure. However, if improvement in morphology by swim-up was high, ovum cleavage rate was low. Sperm morphology within the limits set by our inclusion criteria could not predict the outcome of IVF-ET treatment. It is further concluded that the presence of abnormal spermatozoa at the site of fertilization may be without harm if only the number of normal sperms is high enough.

The value of semen analysis and sperm function assays in predicting pregnancy among infertile couples

Over a 2-year period, 227 couples were evaluated by an extended assessment of the male partner's ejaculate. This extended assessment comprised sperm penetration of denuded hamster oocytes, ability of sperm to penetrate synthetic mucus, and the adenosine triphosphate (ATP) content of whole semen. In proportional hazards analysis adjusting for the contribution of clinical and other seminal variables, the sperm penetration assay (SPA) test was a predictor of pregnancy in the subgroup with normal conventional seminal variables (greater than 40 million motile sperm per ejaculate). When the SPA result was 20% or more the probability of pregnancy was 3.7 times higher; the performance of the SPA as a diagnostic test was better in the couples with treated tubal disease than in other diagnostic categories.

Hypo-osmotic swelling test: analysis of prevasectomy ejaculates

The hypo-osmotic swelling (HOS) test was applied to 1,890 ejaculates obtained from previously fertile men who subsequently underwent a vasectomy. Less than 3% of the ejaculates produced an abnormal HOS test (less than 50% swelling), and more than 95% were normal (greater than or equal to 60% swelling). The sperm concentration and motility data were similar to those obtained by other investigators with prevasectomy ejaculates. Statistically significant but low correlation coefficients were present between the HOS test and these other sperm variables. On the assumption that the large majority of these men were fertile when the ejaculates were produced, the results support the contention that fertility is usually associated with normal or, occasionally, equivocal values in the HOS test.

Hypoosmotic swelling test of sperm

For the diagnosis and evaluation of the therapy for male infertility and for predicting the outcome of AIH and IVF-ET, technically simple, replicable tests that can be performed virtually anywhere and that have definite reliability are required. The results of the HOS test correlate well with the functions of the sperm cell membrane, indicating such aspects as motility, and it is thought to be a particularly effective test of human sperm fertility. Because the HOS test reflects the functions and integrity of the sperm cell membrane, it should be possible to use it to predict the potential for fertilization of frozen sperm.

The prognostic value of a prior spermatozoa study for human in vitro fertilization

Patients admitted for treatment of in vitro fertilization (IVF) were subjected to a semen investigation about 1-2 weeks prior to actual IVF and again during IVF. In addition to routine semen analyses, the recovery efficiency of motile spermatozoa by swim-up technique and Percoll gradient separation, the level of semen lactate dehydrogenase and the viability of the spermatozoa in the insemination medium were also studied. There is a significant correlation between the results of the pre-IVF analyses and that observed during IVF suggesting that a prior investigation of semen profile and sperm function is useful to screen potential IVF candidates. Among the various parameters, sperm motility in the semen and the swim-up preparation, percent normal spermatozoa and in vitro viability were significantly related to the outcome of IVF.

Semen quality and in-vitro fertilization

The standard sperm parameters, and a newly developed assay, the hypoosmotic swelling (HOS) test, of 208 ejaculates were correlated with in vitro fertilization (IVF) outcome to assess their predictive value of the fertilizing capacity of spermatozoa. One hundred fifty-three (73.6%) of the ejaculates possessed spermatozoa that fertilized at least one oocyte and were considered fertile. Among the semen parameters studied, only the HOS test had a relatively high (r = 0.46, p less than 0.001) association with the fertilizing capacity of the spermatozoa. This test was also able to predict the outcome of IVF more reliably than the other semen parameters studied.