Assessment of the dominant abnormal form is useful for predicting the outcome of intracytoplasmic sperm injection in the case of severe teratozoospermia

Stain-Free Sperm Analysis and Selection for Intracytoplasmic Sperm Injection Complying with WHO Strict Normal Criteria

This multi-center study evaluated a novel microscope system capable of quantitative phase microscopy (QPM) for label-free sperm-cell selection for intracytoplasmic sperm injection (ICSI). Seventy-three patients were enrolled in four in vitro fertilization (IVF) units, where senior embryologists were asked to select 11 apparently normal and 11 overtly abnormal sperm cells, in accordance with current clinical practice, using a micromanipulator and 60× bright field microscopy. Following sperm selection and imaging via QPM, the individual sperm cell was chemically stained per World Health Organization (WHO) 2021 protocols and imaged via bright field microscopy for subsequent manual measurements by embryologists who were blinded to the QPM measurements. A comparison of the two modalities resulted in mean differences of 0.18 µm (CI -0.442-0.808 µm, 95%, STD-0.32 µm) for head length, -0.26 µm (CI -0.86-0.33 µm, 95%, STD-0.29 µm) for head width, 0.17 (CI -0.12-0.478, 95%, STD-0.15) for length-width ratio and 5.7 for acrosome-head area ratio (CI -12.81-24.33, 95%, STD-9.6). The repeatability of the measurements was significantly higher in the QPM modality. Surprisingly, only 19% of the subjectively pre-selected normal cells were found to be normal according to the WHO2021 criteria. The measurements of cells imaged stain-free through QPM were found to be in good agreement with the measurements performed on the reference method of stained cells imaged through bright field microscopy. QPM is non-toxic and non-invasive and can improve the clinical effectiveness of ICSI by choosing sperm cells that meet the strict criteria of the WHO2021.

The association of impaired semen quality and pregnancy rates in assisted reproduction technology cycles: Systematic review and meta-analysis

Some studies suggest a relationship between semen quality and pregnancy rates of assisted reproduction technologies (ART). Others have questioned the utility of semen quality as proxy for fertility in couples attempting to conceive with or without assistance. We aimed to investigate the current body of evidence which correlates semen parameters and clinical pregnancy among couples utilizing ART (i.e. in vitro fertilization [IVF], intracytoplasmic sperm injection [ICSI]) through a systematic review and meta‐analysis of cross‐sectional and retrospective cohort studies. Pooled Odd Ratio (OR) for oligo‐, astheno‐ and teratospermic compared to normospermic number of ART cycles were calculated among. Meta‐regression and sub‐group analysis were implemented to model the contribution of clinical/demographic and laboratory standards differences among the studies. Overall, 17 studies were analysed representing 17,348 cycles were analysed. Pooled OR for impaired sperm concentration, motility and morphology was 1 (95%Confidence Interval [CI]: 0.97–1.03), 0.88 (95%CI: 0.73–1.03) and 0.88 (95%CI: 0.75–1) respectively. Further analysis on sperm morphology showed no differences with regard of IVF versus ICSI (p = 0.14) nor a significant correlation with rising reference thresholds (Coeff: −0.02, p = 0.38). A temporal trend towards a null association between semen parameters and clinical pregnancy was observed over the 20‐year observation period (Coeff: 0.01, p = 0.014). The current analysis found no association between semen quality (as measured by concentration, motility or morphology) and clinical pregnancy rates utilizing ART. Future investigations are necessary to explore the association between semen parameters and other ART outcomes (e.g. fertilization, implantation, birth and perinatal health).

Sperm morphology and DNA fragmentation after zona pellucida selection

Sperm DNA fragmentation (SDF) and sperm morphological defects can negatively affect ART outcomes. Consequently, there is a need for additional semen processing technique that accounts for sperm DNA status and morphology prior to ICSI. The objective was to evaluate the efficacy of an additional zona pellucida adhesion-based sperm selection for obtaining sperm populations with a high percentage of normal morphology and DNA integrity as compared to native semen and routine swim-up preparation. Semen samples from 78 normozoospermic men were subjected to swim up and placed in petri dishes coated with 48 acid-solubilized zonae pellucidae. Sperm DNA fragmentation and morphology were assessed in the native semen, the swim-up samples, and the zona-adhered spermatozoa from each patient. The mean sperm DNA fragmentation of the zona-selected spermatozoa (3.5 ± 0.7%) was significantly lower than the swim-up samples (15.3 ± 5.2%) (P  < 0.001) and native semen (24.9 ± 7.1%) (P  < 0.001). All of the samples had lower levels of DNA damage after additional selection by zona pellucida adhesion. Significantly higher percentage of sperm with normal morphology was observed after zona-adhesion selection (11.4 ± 3.9%) when compared to the swim-up samples (8.9 ± 4.3%) (P  < 0.001) or the native semen (5.3 ± 3.2%) (P  < 0.001). In 94% of the samples, the percentage of spermatozoa with normal morphology increased after the additional zona selection. This study demonstrates that sperm selection by additional zona-adhesion technique yields a significantly higher percentage of spermatozoa with normal morphology as well as a significantly decreased level of DNA fragmentation when compared to the native semen and the swim-up-only prepared samples.

LAY SUMMARY

High level of DNA folding known as sperm DNA fragmentation (SDF) inside each sperm and defects in the shape, size, and structure of the sperm can negatively affect assisted reproduction treatment (ART) outcomes. Consequently, there is a need for additional semen processing techniques that account for sperm quality prior to ART. Our team designed a simple technique using proteins from the coat around the egg (zona pellucida) to enhance sperm selection procedures based on natural sperm-egg interactions. Using this technique in combination with the most common techniques used in ART yields a significantly higher percentage of sperm with normal shape, size, and structure and a decreased level of DNA fragmentation. This sperm zona-selection technique would be beneficial if introduced in the ART practice to yield sperm with higher fertilization potential.

Caloric restriction alters the hormonal profile and testicular metabolome, resulting in alterations of sperm head morphology

Energy homeostasis is crucial for all physiological processes. Thus, when there is low energy intake, negative health effects may arise, including in reproductive function. We propose to study whether caloric restriction (CR) changes testicular metabolic profile and ultimately sperm quality. Male Wistar rats (n = 12) were randomized into a CR group fed with 30% fewer calories than weight-matched, ad libitum-fed animals (control group). Circulating hormonal profile, testicular glucagon-like peptide-1 (GLP-1), ghrelin and leptin receptors expression, and sperm parameters were analyzed. Testicular metabolite abundance and glycolysis-related enzymes were studied by NMR and Western blot, respectively. Oxidative stress markers were analyzed in testicular tissue and spermatozoa. Expressions of mitochondrial complexes and mitochondrial biogenesis in testes were determined. CR induced changes in body weight along with altered GLP-1, ghrelin, and leptin circulating levels. In testes, CR led to changes in receptor expression that followed those of the hormone levels; modified testicular metabolome, particularly amino acid content; and decreased oxidative stress-induced damage in testis and spermatozoa, although sperm head defects increased. In sum, CR induced changes in body weight, altering circulating hormonal profile and testicular metabolome and increasing sperm head defects. Ultimately, our data highlight that conditions of CR may compromise male fertility.

When to do intracytoplasmic sperm injection: a prospective comparison

PURPOSE

The purpose of the study was to assess the fertilization rate and embryo development in sibling human oocytes after split insemination in patients with and without isolated teratozoospermia.

METHODS

A prospective cohort study at a university affiliated reproduction center was performed. Hundred and three patients during the time periods 01-2013 to 12-2015 had split insemination ordered for their first IVF cycle. The primary outcome measured was fertilization rate. Secondary outcomes were the number and quality of embryos.

RESULTS

Mature oocytes at the time of collection were assigned as follows: 558 to IVF and 556 to ICSI. An additional 48 immature oocytes matured while awaiting spontaneous fertilization with IVF for a total of 606 in that group. The study group of normal strict sperm morphology ≤ 4 included 61 patients, and the control group included 42 patients with normal strict sperm morphology > 4. ICSI was statistically favored over IVF only in cases with normal strict sperm morphology ≤ 4%. There was a higher fertilization rate in ICSI compared to IVF (74.4% vs. 38%, p < 0.0001), a higher number of day 2 (4 ± 3.4 vs. 2.4 ± 2.7, p < 0.0001), day 3 (4 ± 3.4 vs. 2.2 ± 2.7, p < 0.0001) and day 5 embryos (2.2 ± 2.6 vs. 1.2 ± 2, p = 0.001), and they were of better quality; however, it did not reach significance (p = 0.062). A similar advantage for ICSI was seen in a subgroup of unexplained infertility with normal strict sperm morphology > 4%.

CONCLUSIONS

In conclusion, in couples with normal strict sperm morphology ≤ 4%, there is an advantage of ICSI over IVF in terms of fertilization rate, quantity and quality of cleavage stage embryos and blastocysts. Based on the results, ICSI seems reasonable as a first-line treatment in patients with normal strict sperm morphology ≤ 4%, as well as in patients with unexplained infertility.

Intracytoplasmic sperm injection for male infertility and consequences for offspring

Intracytoplasmic sperm injection (ICSI) has become the most commonly used method of fertilization in assisted reproductive technology. The primary reasons for its popularity stem from its effectiveness, the standardization of the procedure, which means that it can easily be incorporated into the routine practice of fertility centres worldwide, and the fact that it can be used to treat virtually all forms of infertility. ICSI is the clear method of choice for overcoming untreatable severe male factor infertility, but its (over)use in other male and non-male factor infertility scenarios is not evidence-based. Despite all efforts to increase ICSI efficacy and safety through the application of advanced sperm retrieval and cryopreservation techniques, as well as methods for selecting sperm with better chromatin integrity, the overall pregnancy rates from infertile men remain suboptimal. Treating the underlying male infertility factor before ICSI seems to be a promising way to improve ICSI outcomes, but data remain limited. Information regarding the health of ICSI offspring has accumulated over the past 25 years, and there are reasons for concern as risks of congenital malformations, epigenetic disorders, chromosomal abnormalities, subfertility, cancer, delayed psychological and neurological development, and impaired cardiometabolic profile have been observed to be greater in infants born as a result of ICSI than in naturally conceived children. However, as subfertility probably influences the risk estimates, it remains to be determined to what extent the observed adverse outcomes are related to parental factors or associated with ICSI.

Role of Abnormal Sperm Morphology in Predicting Pregnancy Outcomes

The evaluation of strict morphology for predicting successful pregnancy has been controversial, nevertheless remains an essential component of semen analysis. Patients with teratozoospermia (abnormal strict morphology) have traditionally been counseled to undergo assisted reproduction. However, recent studies suggest that patients with abnormal sperm morphology alone should not be precluded from attempting natural conception before undergoing assisted reproduction. The goal of this review is to provide an update on the evaluation of sperm morphology for prognosis in assisted reproductive techniques such as intrauterine insemination and in vitro fertilization with or without intracytoplasmic sperm injection. Additionally, we propose a logical approach to the evaluation of a patient with teratozoospermia seeking fertility treatment.

Beneficial effects of varicocele embolization on semen parameters

BACKGROUND

The value of varicocele repair and the latter's impact on semen parameters are still subject to debate.

METHODS

We analyse changes over time in initially abnormal sperm parameters and serum concentrations of testosterone, FSH and inhibin B after embolization treatment of males with high-grade varicocele. From 2007 to 2012, we recruited 47 male infertile patients with clinically visible left varicocele in the resting patient and at least one abnormal semen parameter. Sperm parameters and serum levels of total testosterone, FSH and inhibin B were measured prior to retrograde embolization (M0) and then 3 (M3) and 6 (M6) months afterwards.

RESULTS

At M0, the median sperm concentration was 5.78 [0.84-37.70] × 10(6)/ejaculate. The mean ± SD sperm progressive motility, vitality and percentage of normal sperm were respectively, 21.83 ± 16.48%, 61.88 ± 15.98% and 12.88 ± 7.15%. The corresponding values at M3 were significantly higher (38.75 [3.96-95] × 10(6)/ejaculate, 29.32 ± 14.21%, 69.14 ± 14.86% and 19.03 ± 11.02%, respectively). The mean percentage of spermatozoa with a thin head was significantly lower at M6 (6.35 ± 5.29%) than at M0 (14.03 ± 13.09%). The mean serum testosterone, FSH and inhibin B levels did not change significantly over time.

CONCLUSIONS

Embolization treatment in men with clinically visible left varicocele, abnormal sperm parameters and documented infertility is associated with a significant improvement in semen parameters including sperm head morphology.

Focus on intracytoplasmic morphologically selected sperm injection (IMSI): a mini-review

Intracytoplasmic sperm injection (ICSI) is the recommended treatment in many cases of male-factor infertility. Several studies have demonstrated a positive correlation between optimal sperm morphology and positive ICSI outcomes. In fact, spermatozoa with severe abnormalities of the head are well documented to be associated with low fertilisation, implantation and pregnancy rates. However, a spermatozoon which is classified as 'normal' by microscopic observation at low magnification could contain ultrastructural defects that impair both the fertilisation process and embryonic development. The intracytoplasmic morphologically selected sperm injection (IMSI) procedure changed the perception of how a spermatozoon suitable for injection should appear. Sperm selection is carried out at ×6000 magnification, allowing improved assessment of the sperm nucleus. Currently, standardized clinical indications for IMSI are lacking and the candidates are selected on the grounds of their medical history or of a careful analysis of the sperm suspension. Further prospective randomized studies are needed to confirm the advantages of IMSI in specific groups of patients. In addition to providing a brief overview of the IMSI procedure, this study aims to review the literature, which explains the theoretical basis and the clinical outcomes of this technique. Several reports show that IMSI is associated with improved implantation and clinical pregnancy rates as well as lower abortion rates when compared to ICSI. Although a possible correlation between the sperm's abnormal nucleus shape, increased DNA fragmentation and negative laboratory and clinical outcomes has been long investigated, the results are conflicting.

Quality of human spermatozoa: relationship between high-magnification sperm morphology and DNA integrity

The aim of this work is to establish the relationship between the morphology of Intracytoplasmic Morphologically Selected Sperm Injection (IMSI)-selected spermatozoa and their DNA integrity. The 45 ejaculates were randomly distributed into three treatment groups: normozoospermic, oligoasthenozoospermic and oligoasthenotheratozoospermic samples. The evaluation of DNA integrity was performed using the sperm chromatin dispersion test. It was established that DNA integrity of spermatozoa is strongly dependent on ejaculate quality (P < 0.05). The count of spermatozoa with nonfragmented DNA in normozoospermic samples was high and independent from IMSI-morphological classes (Class 1 versus Class 3, respectively) (P > 0.1). With decreased ejaculate quality, the percentage of spermatozoa with nonfragmented DNA decreased significantly (P < 0.05) independent from morphological class. Nevertheless, the rate of IMSI-selected spermatozoa with fragmented DNA within of Class 1 in normozoospermic (Group 1), in oligoasthenozoospermic (Group 2) and in oligoasthenotheratozoospermic (Group 3) samples was 21.1%, 31.8% and 54.1%, respectively. In conclusion, there is a direct relationship between morphological parameters of spermatozoa and their DNA integrity. However, the IMSI technique alone is not enough for the selection of spermatozoa with intact nuclei.

CASA derived human sperm abnormalities: correlation with chromatin packing and DNA fragmentation

PURPOSE

The present study was undertaken to evaluate the effects of morphokinetic abnormalities of human spermatozoa on chromatin packing and DNA integrity and possible beneficial effects of sperm selection in ICSI.

METHODS

Semen samples from 1002 patients were analysed for morphology and motility using CASA. Protamine status and DNA fragmentation were analysed by chromomycin A3 staining and sperm chromatin dispersion assay respectively.

RESULTS

Sperms with elongated, thin, round, pyri, amorphous, micro and macro forms were significantly higher in teratozoospermic and oligoasthenoteratozoospermic groups. Significant difference in chromatin packing and DNA fragmentation index was observed in these abnormal groups compared with normal. Similarly significant correlation was also seen between abnormal motility parameters and DNA fragmentation index in asthenozoospermic group compared with normal.

CONCLUSIONS

Specific abnormal morphological forms have higher incidence of chromatin packing abnormalities and DNA fragmentation. Using these sperms in ICSI might have an impact on fertilization, embryo development and abortion rates. These can be selectively avoided during ICSI procedure to improve ART outcome.

Outcome of conventional IVF and ICSI on sibling oocytes in the case of isolated teratozoospermia

PURPOSE

To reevaluate the effect of isolated teratozoospermia on IVF and determine if there was any therapeutic benefit to isolated teratozoospermia by ICSI, since there are no widely accepted criteria for the treatment technique about isolated teratozoospermia.

METHODS

A total of 441 couples with >20 million and progressive motility >30 % sperm undergoing their first IVF/ICSI cycle were included in the study between 2008 and 2010, for whom at least 8 oocytes were retrived. Isolated teratozoospermia was diagnosed in 183 of the included couples, and the rest couples (normal sperm morphology) were studied as control. Sibling oocytes were randomized to be inseminated either by ICSI or IVF. Fertilization rate, embryo quality, pregnancy rate, implantation rate and spontaneous abortion rate were assessed.

RESULTS

There was no difference in the percentage of eggs fertilized, implantation rate, pregnancy rate and spontaneous abortion rate between conventional IVF and ICSI regardless of the percentage of normal morphology. The day 3 embryonic morphology and rate of development were not different despite the insemination method and percentage of normal morphology.

CONCLUSION

Because isolated teratozoospermia did not influence the major indices of IVF and the unnecessary use of ICSI is time-consuming, costly and potential risks, couples with isolated teratozoospermia need not be subjected to ICSI.

Measurement and significance of sperm morphology

The measurement or evaluation and clinical significance of human sperm morphology has always been and still is a controversial aspect of the semen analysis for the determination of a male's fertility potential. In this review the background of the development of the evaluation criteria for sperm morphology will be discussed. Aspects of criticism on the strict criteria definition and use of the criteria for sperm morphology evaluation will be discussed as well as possible reasons for the decline in normal sperm morphology values and how we can compromise for this phenomenon resulting in the very low normal reference value as published in the 2010 WHO manual for the Examination and Processing of Human Semen. One of the possible solutions may be to give more attention to a limited number of abnormal sperm morphology categories and the inclusion of sperm morphology patterns. It is concluded in this review that if done correctly and with care and with strict application of existing guidelines as outlined in the 2010 WHO manual, sperm morphology measurement still has a very important role to play in the clinical evaluation of male fertility potential.

The relationship between isolated teratozoospermia and clinical pregnancy after in vitro fertilization with or without intracytoplasmic sperm injection: a systematic review and meta-analysis

We conducted a systematic review and meta-analysis of data from the literature from the years 1986 to 2009 using teratozoospermia and fertilization or IVF or in vitro fertilization as the keywords. A total of 31 studies were identified, and 4 met the inclusion criteria. Isolated teratozoospermia was not associated with a statistically significantly decreased probability of pregnancy with assisted reproduction.

Clinical significance of the low normal sperm morphology value as proposed in the fifth edition of the WHO Laboratory Manual for the Examination and Processing of Human Semen

The very low cut-off value for sperm morphology of 4% morphologically normal spermatozoa, as proposed in the new edition of the World Health Organization (WHO) manual on semen analysis, is in agreement with recently published values and reflects the trend of a decline in reported mean values for normal sperm morphology. The reduced value for morphologically normal spermatozoa over the years may be due to several factors. The first is the introduction of strict criteria for the evaluation of sperm morphology. Other reasons may include the introduction of additional criteria for sperm morphology abnormalities and the suggested decrease in semen parameters because of increasing negative environmental influences. Although on its own the newly proposed very low normal value may not provide the strong predictive value for a males' fertility potential, as originally reported for sperm morphology evaluated according to strict criteria, a good predictive value can still be obtained if the holistic, strict approach for sperm morphology evaluation is followed together with additional sperm morphology parameters now available, because certain morphology patterns and sperm abnormalities are now known to be of strong prognostic value. In addition, better international standardization of the technical methodology, consensus on the interpretation of sperm morphology evaluation criteria and standardized international external quality control (EQC) schemes, are of utmost importance to maintain the good predictive value of sperm morphology.

Sperm morphological abnormalities as indicators of DNA fragmentation and fertilization in ICSI

PURPOSE

To determine the relationship between sperm morphological abnormalities, DNA fragmentation and fertilization rate in intracytoplasmic sperm injection (ICSI).

METHODS

Sperm samples from 20 ICSI cycles were analysed. Morphology was assessed according to strict criteria, and DNA fragmentation was measured by terminal deoxynucleotidyl transferase (TdT)-mediated fluorescein-dUTP nick end labelling (TUNEL) using flow cytometry.

RESULTS

A negative correlation was found between the percentage of spermatozoa with elongated heads and fertilization rate. There was a significant difference in the amount of morphological abnormalities between sperm samples with low and high degree of DNA fragmentation. The percentages of amorphous heads and overall head abnormalities were significantly higher in sperm samples with elevated degree of DNA fragmentation. No correlation was found between sperm DNA fragmentation and fertilization rate.

CONCLUSIONS

Head abnormalities, especially amorphous heads, are related to elevated degree of DNA fragmentation. Elongated heads, when detected as predominant abnormal form in sperm samples, may affect fertilization in ICSI.

Ultrastructural nuclear defects and increased chromosome aneuploidies in spermatozoa with elongated heads

BACKGROUND

Cellular and molecular mechanisms leading to elongated sperm heads are not known. We have analysed the nuclear status of spermatozoa with elongated heads.

METHODS

Fourteen men with at least 30% of spermatozoa with an elongated nucleus were studied and compared with five fertile men as controls. Sperm morphology was analysed by a quantitative ultrastructural analysis. Sperm chromosomal content was assessed by three-colour fluorescence in-situ hybridization (chromosomes X, Y, 18). Y chromosome microdeletion and karyotype were analysed.

RESULTS

Elongated sperm head rates of the patients were 46.9% (30-75 versus 0-2% in the control group) by light microscopy and 34.4% by electron microscopy. In all patients, the chromatin was poorly condensed in elongated sperm heads (50% of elongated nuclei). No anomalies of sperm biochemical markers were found. All the men showed normal karyotype (46,XY) and absence of Y chromosome microdeletion. Aneuploidy rates of gonosomes and chromosome 18 were significantly increased in patients (1.64- and 3.6-fold, P = 0.006 and 0.026, respectively).

CONCLUSIONS

This study demonstrates that impaired chromatin compaction and slightly increased chromosome aneuploidies are found in spermatozoa with an elongated head, suggesting possible mechanisms such as meiotic non-disjunctions or spermiogenesis anomalies.

Does the presence of nuclear vacuoles in human sperm selected for ICSI affect pregnancy outcome?

BACKGROUND

To verify whether or not microinjection of sperm with a normal nuclear shape but large vacuoles affects IVF-ICSI pregnancy outcome.

METHODS

A comparative study testing IVF outcome parameters of IVF-ICSI, based on morphological selection of spermatozoa with normal nuclei against those based on microinjection of sperm with a normal nuclear shape but large vacuoles. An experimental group, including 28 IVF-ICSI cycles, where only embryos obtained from microinjection of spermatozoa with a normal nuclear shape but large vacuoles were transferred, was matched with a control group, including 28 IVF-ICSI cycles, where only embryos obtained from microinjection of spermatozoa with a strictly defined morphologically normal nuclear shape and content were transferred. The main outcome was IVF-ICSI pregnancy rate.

RESULTS

The experimental group exhibited a significantly lower pregnancy rate per cycle and significantly higher abortion rate per pregnancy compared to the control group (18 versus 50%, and 80 versus 7%, respectively, P=0.01).

CONCLUSION

Microinjection of vacuolated sperm appears to reduce the pregnancy rate and appears to be associated with early abortion.

Real-time fine morphology of motile human sperm cells is associated with IVF-ICSI outcome

The aim of the present prospective study was to determine whether subtle sperm morphological characteristics affect the outcome of intracytoplasmic sperm injection (ICSI), and if so, to identify those that are relevant. For this purpose, we developed a new method, the motile sperm organelle morphology examination (MSOME). The examination is performed in real time using an inverted light microscope equipped with high-power Nomarski optics enhanced by digital imaging to achieve a magnification up to 6300x. MSOME was applied to the leftover sperm fraction selected for microinjection in 100 random couples referred for ICSI treatment at 3 major in vitro fertilization centers. We found that the morphological normalcy of the entire sperm cell, according to MSOME criteria, was positively associated with ICSI fertilization rate (area under the receiver operating characteristics [ROC] curve, 88%) but not with pregnancy outcome. The morphological normalcy of the sperm nucleus, defined by MSOME, was significantly and positively associated with both fertilization rate and pregnancy outcome (areas under the ROC curve, 72% and 74%, respectively). These findings indicate that ICSI-associated pregnancy rate may be affected by subtle morphological malformations of the sperm nucleus, which may remain undetected by the embryologist during the routine selection procedure.