Predictive value of cytoplasmic granulation patterns during in vitro fertilization in metaphase II oocytes: Part I, poor-prognosis patients

The effect of sperm DNA fragmentation on ICSI outcomes depending on oocyte quality

BACKGROUND

Sperm deoxyribonucleic acid (DNA) fragmentation is commonly encountered in spermatozoa, and the oocyte assumes responsibility for repairing sperm DNA fragmentation during the oocyte-embryo transition.

OBJECTIVES

This study aimed to investigate whether the effect of sperm DNA fragmentation on intracytoplasmic sperm injection outcomes depends on the incidence of oocyte dimorphisms.

MATERIALS AND METHODS

For the present cohort, 2942 fertilized oocytes from 525 patients submitted to intracytoplasmic sperm injection cycles were assessed. The present study was conducted in a private in vitro fertilization center affiliated to a university from June 2016 to July 2019. Semen samples were divided into the following two groups depending on the sperm DNA fragmentation index: a low fragmentation index group (<30% sperm DNA fragmentation, n = 1468) and a high fragmentation index group (≥30% sperm DNA fragmentation, n = 486). In addition, mature oocytes were examined before sperm injection, and intracytoplasmic and extracytoplasmic defects were recorded. The effect of the sperm DNA fragmentation index on laboratory and clinical intracytoplasmic sperm injection outcomes (depending on the presence of oocyte defects) was evaluated.

RESULTS

Significant increases in the rates of fertilization, high-quality embryo, implantation, and pregnancy were noted for cycles with <30% sperm DNA fragmentation than cycles with ≥30% sperm DNA fragmentation (regardless of the presence of oocyte dimorphisms). The presence of dimorphisms significantly impacted laboratory and clinical outcomes. The lowest fertilization and high-quality embryo rates were observed when a high sperm DNA fragmentation index was associated with the presence of dark cytoplasm, vacuoles, resistant membrane, and non-resistant membrane. The lowest implantation and pregnancy rates were observed when a high sperm DNA fragmentation index was associated with the presence of vacuoles, defective perivitelline space, and fragmented polar body. The effect of sperm DNA fragmentation on miscarriage rates was significantly influenced by the presence of centrally located cytoplasmic granulation, a defective perivitelline space and non-resistant membrane.

CONCLUSION

A high sperm DNA fragmentation index increases the likelihood of miscarriage in intracytoplasmic sperm injection cycles, an effect that may potentially be magnified by the presence of oocyte dysmorphisms.

Effects of different oocyte cytoplasmic granulation patterns on embryo development and euploidy: a sibling oocyte control study

PURPOSE

This study evaluated the relationship between cytoplasmic granulation patterns and the developmental potential of mature sibling oocytes.

METHODS

Data from 54 cycles of preimplantation genetic tests for structural rearrangement from July 2019 to June 2022 were analyzed. In total, 564 embryos were cultured using a time-lapse system. Sibling oocytes were divided into four groups based on cytoplasmic granulation patterns: fine granulation (FG) group (n = 177), central granulation (CG) group (n = 183), dispersed granulation (DG) group (n = 161), and uneven granulation (UG) group (n = 43). The CG group was further divided into three groups (grades I, II, and III) based on the tertile of the ratio of central granular distribution area to oocyte area. Fertilization rate, embryo morphokinetics, chromosomal ploidy, and clinical outcomes of the groups were compared.

RESULTS

No significant differences were observed in morphokinetic parameters, fertilization rate, embryo production, blastocyst formation, and aneuploidy rates among the different cytoplasmic-granulation pattern groups. However, embryos derived from CG oocytes showed significantly higher aneuploidy rates in grade III compared to grade I (86.21% vs 61.54%, P = 0.036) or grade II (86.21% vs 56.00%, P = 0.013). Thirty embryos were transferred to the uteri of female patients and the clinical pregnancy and live birth rates did not significantly differ among groups.

CONCLUSIONS

Cytoplasmic granulation patterns may not affect embryo fertilization, development speed, and aneuploidy rates. However, a higher grade of CG may be associated with increased aneuploidy rates. Larger sample sizes are required to explore the impact of oocyte cytoplasmic granulation patterns on embryo implantation potential.

The impact of oocyte central granularity on ICSI practice: developmental competence of dysmorphic and morphologically normal companion oocytes

PURPOSE

To assess the effects of oocyte central granularity and its underlying endocrine environment on developmental competence of dysmorphic and morphologically normal oocytes.

METHODS

Retrospective cohort study including 1,082 patients undergoing autologous ICSI cycles. Of these, 211 patients provided 602 oocytes with central granularity (CG) and 427 morphologically normal cycle companion oocytes (NCG). The remaining 871 patients provided only morphologically normal oocytes in cycles not yielding dysmorphic oocytes (N). Patient profile associated with CG was characterized, and fertilization rates, early morphokinetics and live birth rates were compared between N, CG and NCG groups. Patient characteristics associated with implantation and delivery performance of CG-derived embryos were assessed.

RESULTS

CG was associated with higher maternal age, basal FSH concentrations and total FSH dose, but with lower circulating AMH (p ≤ 0.035). Fertilization rates were reduced and early morphokinetic parameters were delayed in CG (p < 0.025) and NCG (p < 0.05) groups as compared to the N group. Embryos derived from CG oocytes achieved a markedly lower live birth rate (14.9%) as compared to those derived from NCG (36.8%; p = 0.03) and N oocytes (29.8%; p = 0.002). The negative relationship between CG and live birth was confirmed by a multivariate analysis controlling for potential confounders (OR:2.59, IC:1.27-5.31; P = 0.009). Implantation and delivery rates following transfers of CG-derived embryos were inversely associated with maternal age.

CONCLUSION

CG oocytes, but not their morphologically normal cycle companions, have severely compromised developmental competence. Maternal age should be a key parameter in deciding whether or not to utilize CG oocytes in ICSI cycles.

Changing clinical significance of oocyte maturity grades with advancing female age advances precision medicine in IVF

In current IVF practice, metaphase-2 (M2) oocytes are considered most efficient in producing good quality embryos. Maximizing their number at all ages is standard clinical practice, while immature germinal vesicle (GV) oocytes are mostly automatically discarded. We present preliminary evidence that oocyte maturity grades with advancing age significantly change in their abilities to produce good quality embryos, with M2 oocytes significantly declining, GV oocytes improving, and M1 oocytes staying the same. These data contradict the over-40-year-old dogma that oocyte grades functionally do not change with advancing age, supporting potential changes to current IVF practice: (1) Stimulation protocols and timing of oocyte retrieval can be adjusted to a patient's age and ovarian function. (2) In older and younger women with prematurely aging ovaries, GV oocytes may no longer be automatically discarded. (3) In some infertile women, rescue in vitro maturation of immature oocytes may delay the need for third-party egg donation.

Different occurrence rates of centrally located cytoplasmic granulation in one cohort oocytes show distinctive embryo competence and clinical outcomes

Centrally located cytoplasmic granulation (central granulation) is a common cytoplasmic dysmorphism in human oocytes retrieved after controlled ovarian hyperstimulation (COH). In order to achieve a better understanding of its formation and effects on clinical outcomes, we retrospectively analyzed 422 ICSI treatment cycles. Three groups of patients were classified according to the ratio of central granulation occurrence in one egg cohort, as partial granulation, all granulation and control groups. The partial granulation group had a significantly lower BMI and higher AMH level compared to the control or all granulation groups. Consistent with these distinctive features in the partial granulation group, fertilization and blastocyst formation rates were reduced significantly in the partial granulation group but not in the all granulation group. Furthermore, the clinical outcomes in fresh embryo transfer cycles were dramatically reduced in the partial granulation group compared with the control group. However, in FET cycles, all three clinical outcomes were significantly reduced in the all granulation group but not in the partial granulation group. We propose that partial granulation may reflect a specific population of patients, and that the central granulation structure is sensitive to cryopreservation.