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

Comparative analysis of three sperm DNA damage assays and sperm nuclear protein content in couples undergoing assisted reproduction treatment

STUDY QUESTION

Is there an association between sperm DNA damage, measured by three different assays, sperm nuclear protein content and clinical outcomes in assisted reproduction treatment (ART)?

SUMMARY ANSWER

Sperm DNA damage measured by terminal deoxynucleotidyltransferase-mediated dUTP nick-end labelling (TUNEL) and the Comet assay were significantly associated with ART outcomes in our single institution study.

WHAT IS KNOWN ALREADY

Abnormal protamine expression is known to be associated with sperm DNA damage and male infertility. A number of studies have shown a significant relationship between sperm DNA damage and ART outcomes. To date, there are no large studies providing direct comparisons of DNA damage tests within the same study population. Thus, the prognostic value for each method remains unknown.

STUDY DESIGN, SIZE, DURATION

Cross-sectional study of 238 men from infertile couples undergoing ART at the University Center for Reproductive Medicine, Utah, USA, between April 2011 and March 2013.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Sperm from men undergoing ART were tested for DNA damage using the alkaline Comet assay, TUNEL and flow cytometric chromatin evaluation (FCCE) assays. Histone retention was analysed using the aniline blue staining method, whereas protamine content (proteins P1 and P2) and ratio were analysed using acid urea gel electrophoresis. The prognostic value of each sperm DNA test to predict clinical pregnancy was calculated.

MAIN RESULTS AND THE ROLE OF CHANCE

Histone retention was associated with sperm DNA damage (P < 0.001), reduced embryo quality (P = 0.005) and clinical pregnancies (P < 0.001). The mean percentage of sperm with DNA damage was significantly higher in sperm from non-pregnant couples compared with that from pregnant couples, as measured by TUNEL assay (15.04 ± 1.16% versus 8.79 ± 0.56%; P < 0.001) and alkaline Comet assay (72.79 ± 2.49% versus 55.86 ± 2.29%; P < 0.001). There was no association between clinical pregnancies and DNA fragmentation index measured by FCCE (12.97 ± 1.46 versus 14.93 ± 1.65; P = 0.379). Of the protamine parameters analysed, only the P1/P2 ratio was associated with sperm count (P = 0.013), men's age (P = 0.037), maturity (P = 0.049) and blastocyst quality (P = 0.012). Histone retention and sperm DNA damage measured by Comet and TUNEL assays were associated with fertilization rate (P < 0.05), embryo quality (P < 0.05) and implantation rate (P < 0.05).

LIMITATIONS, REASONS FOR CAUTION

A potential drawback of this study is that it is cross-sectional. Generally in such studies there is more than one variable that could cause the effect. Analysing sperm is one part of the equation; there are also a number of female factors that have the potential to influence ART outcomes. Therefore, given the large and well-established role of female factors in infertility, normal sperm DNA integrity and protamination do not necessarily ensure clinical pregnancy in ART. Thus, female factors can reduce the prognostic value of sperm DNA tests. Further, our use of native semen instead of prepared sperm may have iatrogenically increased the DNA damage.

WIDER IMPLICATIONS OF THE FINDINGS

Alteration in sperm nuclear protein affects sperm DNA integrity. Further, with the current dataset, TUNEL and Comet assays appeared more predictive of ART success than FCCE.

STUDY FUNDING/COMPETING INTEREST(S)

No personal or direct financial support has been received for any of this work. The authors declare no competing interests.

TRIAL REGISTRATION NUMBER

N/A.

ICSI improves fertilization in isolated teratozoospermic men: a study with strictly controlled external factors and WHO-5 standard

A clear clinical management pathway (conventional in vitro fertilization, IVF or intracytoplasmic sperm injection, ICSI) for treating patients with teratozoospermia is lacking. Here we conducted a retrospective study of fertility indices in 2,178 IVF/ICSI cycles in order to reevaluate clinical management of couples with isolated teratozoospermia (< 4% morphologically normal sperms and normal sperm concentration and motility with the standard of WHO-5).We strictly controlled external factors that could affect oocyte quality or endometrial receptivity to minimize the impact of confounders. Fertilization, total fertilization failure, embryo quality, blastocyst formation rate, and pregnancy rate were studied. Retrospectively, in conventional IVF cycles a significantly lower fertilization rate and higher total fertilization failure rate were observed in couples with isolated teratozoospermia as compared to couples with a normal semen profile. Furthermore, when ICSI was used to treat these teratozoospermic couples, improvement in fertilization was noted. However, the embryo quality, blastocyst formation rate, and pregnancy of couples with isolated teratozoospermia were not enhanced by ICSI. Multiple variable analysis showed that many factors including percentage of morphologically normal sperm are statistically correlated with fertilization rate and total fertilization failure in conventional IVF cycles. In addition the insemination method was correlated with fertilization rate in cases with isolated teratozoospermia. Further studies are warranted to compare outcomes of conventional IVF and ICSI in cases of isolated teratozoospermia, where less than 5 oocytes are retrieved.

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.

Male factor infertility and ART

For years, the management and treatment of male factor infertility has been 'experience' and not 'evidence' based. Although not evidence-based, current clinical practice involves extensive use of assisted reproductive techniques (ART). Where specific treatments are not indicated or have failed, ART have become popular adjunctive treatments for alleviating male factor infertility. According to the limited evidence available, intrauterine insemination (IUI) may be considered as a first-line treatment in a couple in which the female partner has a normal fertility status and at least 1×10(6) progressively motile spermatozoa are recovered after sperm preparation. If no pregnancy is achieved after 3-6 cycles of IUI, optimized in vitro fertilization (IVF) can be proposed. When less than 0.5×10(6) progressively motile spermatozoa are obtained after seminal fluid processing or sperm are recovered surgically from the testis or epididymis, intracytoplasmic sperm injection (ICSI) should be performed. Although the outcome of no other ART has ever been scrutinized as much before, no large-scale 'macroproblems' have as yet been observed after ICSI. Yet, ICSI candidates should be rigorously screened before embarking on IVF or ICSI, and thoroughly informed of the limitations of our knowledge on the hereditary aspects of male infertility and the safety aspects of ART.

De la nature des vacuoles spermatiques aux résultats et indications de l’IMSI (intracytoplasmic morphologically selected sperm injection)

En MSOME (high-magnification motile sperm organelle morphology examination), certains spermatozoïdes jugés normaux au grossissement × 400 ou × 200 peuvent présenter des vacuoles céphaliques. Si la large vacuole est décrite comme une empreinte de pouce nucléaire, la nature des vacuoles pourrait dépendre de leur taille, du nombre, de leur localisation et de leur profondeur. Cette revue de la littérature débat de la nature des vacuoles, analyse les résultats obtenus en IMSI (intracytoplasmic morphologically selected sperm injection) et en liste les indications.

Severe teratozoospermia and its influence on pronuclear morphology, embryonic cleavage and compaction

BACKGROUND

Fertilization, cell division and embryo development depend on genomic contributions from male and female gametes. We hypothesize that teratozoospermic sperm influences early embryo development and embryo compaction.

METHODS

We conducted a retrospective analysis of embryos derived from intracytoplasmic sperm injection (ICSI) cycles. Two hundred thirty-five consecutive ICSI cycles were included in the study; all treatment was provided at the Cleveland Clinic Fertility Center. Patient cycles were divided by sperm morphology based on Kruger's strict criteria: Group A, embryos where teratozoospermic sperm (0-2% normal) were used for ICSI and Group B, embryos where dysmorphic sperm (5-13% normal) were used for ICSI. All cycles analyzed were of patients doing day 3 embryo transfers. Outcome measures assessed included pronuclear (PN) pattern, syngamy, early cleavage, cell number, rate of compaction and blastulation of embryos left in culture and not transferred on day 3.

RESULTS

A total of 1762 embryos were analyzed. PN patterns were similar in Group A and Group B embryos. No differences were noted in syngamy, cleavage, cell number or blastulation rate. Studying the development of embryos in culture after day 3 transfer revealed a difference in the timeline for compaction. By day 4, 25% of Group A embryos had compacted compared to 36% in Group B (P = 0.0007). There was no difference found between Group A and Group B embryos in regards to blastulation.

CONCLUSIONS

We did not find an association between sperm morphology and clinical outcomes. The impact of teratozoospermia may be masked in ICSI cycles where fertilization, implantation rate and clinical pregnancy rate are the primary outcome measures. However, by examining the timeline of development, we were better able to discern a potential paternal effect at critical transition points from fertilization through activation.