Effect of cumulus cell removal on the fertilization and the day 3 embryo quality in human IVF

Early cumulus cell removal increases cumulative live birth rate while having no negative effect on the malformation rate in in vitro fertilization: a propensity score-matched cohort study

PURPOSE

The aim of this study was to investigate the efficacy and safety of early cumulus cell removal (ECCR) during human in vitro fertilization (IVF).

METHODS

A retrospective analysis was performed between January 2011 and December 2019. The study enrolled 1131 couples who underwent IVF treatment with ECCR. After propensity score matching at a 1:1 ratio, 1131 couples who underwent overnight coincubation of gametes were selected. The main outcome measure was the cumulative live birth rate. Secondary outcome measures included the cumulative pregnancy rate, polyspermy rate, available embryo rate, miscarriage rate, malformation rate, time to live birth, and oocyte-to-baby rate.

RESULTS

There were no significant differences found between the two groups in the polyspermy rate, available embryo rate, miscarriage rate, time to live birth, oocyte-to-baby rate, and neonatal congenital anomalies rate. The results of the study showed that ECCR was associated with a significantly higher cumulative live birth rate and cumulative pregnancy rate, along with a significantly lower fertilization rate.

CONCLUSIONS

ECCR tended to confer increased cumulative live birth rate and had no negative effect on the neonatal malformation rate.

A randomized triple blind controlled trial comparing the live birth rate of IVF following brief incubation versus standard incubation of gametes

STUDY QUESTION

Does brief incubation of oocytes and spermatozoa improve the live birth rate (LBR) of IVF when compared with that of standard incubation?

SUMMARY ANSWER

Brief incubation of gametes does not improve the LBR of IVF when compared with standard incubation.

WHAT IS KNOWN ALREADY

Some small randomized studies showed that brief incubation was associated with a significantly higher ongoing pregnancy rate than standard incubation.

STUDY DESIGN, SIZE, DURATION

This is a randomized triple blind study of 320 infertile women for their first or repeated cycles undergoing IVF between September 2015 and October 2016.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Women were randomized into the brief incubation group (n = 160) or the standard incubation group (n = 160) according to a computer-generated randomization list. Oocytes were incubated with spermatozoa (0.3-1.2 million motile sperm/ml) for 3-4 h in the brief incubation group while oocytes were incubated with spermatozoa at similar concentration for 20 h in the standard incubation group. The primary outcome was the LBR (a baby born alive after 22 weeks gestation) in the fresh cycle.

MAIN RESULTS AND THE ROLE OF CHANCE

There was no significant difference in the LBR between the brief and standard incubation groups based on both intention-to-treat [33.0% (53/160) versus 36.8% (59/160), relative risk (RR) 0.898 (95% CI = 0.666-1.212), P = 0.482] and per protocol [41.4%(53/128) versus 41.0% (59/144), RR1.011 (95% CI = 0.760-1.343), P = 0.942] analyses. Clinical pregnancy, ongoing pregnancy, miscarriage, multiple pregnancy and implantation rates were comparable for the two groups. Similar results were found with subgroup analysis of advanced maternal age, abnormal semen analysis and repeated IVF cycles. No differences were observed in cumulative LBR between two groups.

LIMITATIONS, REASONS FOR CAUTION

Various motile sperm concentrations of 0.3-1.2 million per ml were used for insemination and the reactive oxygen species level in the insemination medium was not measured. The highest level at 1.2 million per ml is still relatively low compared to prior studies, therefore we do not know whether brief incubation can improve the LBR using higher concentrations of spermatozoa. The present sample size may not be adequate to detect a smaller difference in the LBR.

WIDER IMPLICATIONS OF THE FINDINGS

The present study demonstrated that a brief incubation of gametes had no significant beneficial effect on the LBR when compared with the standard incubation. The practice of brief incubation of gametes is not necessary and this can save the already tight manpower in many laboratories.

STUDY FUNDING/COMPETING INTERESTS

The study was supported by the Merck-Serono China Research Fund for Fertility Experts (2015), which was not involved in study design, execution, data analysis and manuscript preparation. There are no conflicts of interest for all authors.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov Identifier NCT02534857.

TRIAL REGISTRATION DATE

28 August 2015.

DATE OF FIRST PATIENT’S ENROLMENT

8 September 2015.

Influence of heparin or the presence of cumulus cells during fertilization on the in vitro production of goat embryos

Considerable research has been focused on in vitro production (IVP) of goat embryos to improve its efficiency. In Experiment 1, the effect of the cumulus cells by comparing slaughterhouse-oocytes denuded on purpose (DOP) prior to IVF to intact COC, and the effect of heparin during IVF were assessed. In Experiment 2, oocytes that were already denuded at collection (DOC), DOP and intact COC were studied. Three treatments used oocytes denuded at collection: DOC oocytes were cultured alone for both IVM and IVF; DOC and COC were cultured together for both IVM and IVF or DOC were IVM alone and then mixed with COC for IVF. In other treatments, COC were allocated to four IVF treatments: Intact COC; COC were denuded prior to IVF; COC were denuded and IVF with added cumulus cells; COC were denuded and IVF mixed with intact COC giving two sub-treatments: Denuded oocytes that were IVF with COC; and COC that were IVF with denuded oocytes. After fertilization, all presumptive zygotes were cultured for 8 days. In Experiment 1, the yield of blastocysts as a proportion of total oocytes was greater (P<0.05) for COC that were IVF in the presence of heparin (54%) than without heparin (42%) or oocytes already denuded at collection that were IVF with or without heparin (41%; 38%; respectively). In Experiment 2, the developmental potential of oocytes denuded at collection was reduced (cleavage and blastocyst rates calculated from total oocytes: 34%; 11%, respectively) as compared to COC (77%; 59%, P<0.05). However, when equal numbers of both were mixed at the start of IVM, the rates were not significantly different to COC alone (68%; 45%), but when both were mixed equally only for IVF, the rates were reduced (57%; 40%, P<0.05). Denuded oocytes co-cultured with cumulus cells were not significantly different to intact COC (76%; 55%). The effect of adding COC during IVF to oocytes denuded after IVM was similar to adding cumulus cells to the same type of oocytes. In conclusion, both the use of heparin and the association of oocytes with cumulus cells, either detached or in intimate contact, during IVM and/or IVF significantly improve IVP of goat embryos. Furthermore, some oocytes that are already denuded at collection will develop satisfactorily to blastocysts when matured and fertilized with intact COC.

Effects of cumulus cells removal after 6 h co-incubation of gametes on the outcomes of human IVF

PURPOSE

To investigate the effects of cumulus cells removal after 6 h co-incubation of gametes on the fertilization, polyspermy, multinucleation and clinical pregnancy rates in human IVF.

METHODS

A total of 1,200 IVF-ET cycles undergoing 6 h co-incubation of gametes in 2009 were included in this study. Inclusion criteria were: female age <38 years, first IVF treatment, with bi-ovary and normal ovarian response, e.g., 4 ~ 20 oocytes could be obtained. A 6 h period of co-incubation was applied in all IVF cycles. According to the history of infertility, cumulus cells were mechanically removed either 6 h post-insemination or 20 h post-insemination. For couples with primary infertility, or unexplained infertility, or mild oligospermia or asthenospermia, the cumulus cells were removed at 6 h of insemination for the polar body observation (6 h group, n = 565). Of these, 80 cycles received early rescue ICSI due to fertilization failure or low fertilization rate at 6 h of insemination. For couples with secondary infertility and normal semen analysis, the cumulus cells were removed at 20 h of insemination as routine (20 h group, n = 635). Of these, three cycles received late rescue ICSI due to fertilization failure at 20 h of insemination. Normal fertilization, polyspermy (≥3PN), multinucleation and clinical pregnancy rates were compared between the two groups (rescue ICSI cycles were not included in the comparison in both groups).

RESULTS

Significant difference (P < 0.05) was observed between the groups regarding polyspermy rates (7.48% in 6 h group and 9.22% in 20 h group). No difference was observed between the groups regarding normal fertilization rates (2PN rate) (64.89% in 6 h group and 65.74% in 20 h group). No difference was observed between the groups regarding multinucleation and clinical pregnancy rates (11.01% and 65.15% in 6 h group, 10.75% and 66.93% in 20 h group, respectively). The clinical pregnancy rate was 51.43% in cycles receiving early rescue ICSI, while no clinical pregnancy was obtained in cycles receiving late rescue ICSI.

CONCLUSION

The present results indicate that cumulus cells removal at 6 h of insemination is a relatively safe operation, which yielded comparable normal fertilization rate, multinucleation and clinical pregnancy rates compared with 20 h group. This protocol may be beneficial for early obsevation of fertilization failure and make early rescue ICSI possible.