Case Presentation: Arrested Oocyte Maturation in a Young Patient

Clinical Summary

A 32-year-old woman underwent three ovarian stimulation cycles using an antagonist protocol. Both urinary and recombinant gonadotropins were employed across the cycles. In each case, serum estradiol levels reached appropriate levels (often exceeding 2000 pg/mL), and follicular growth was adequate, with dominant follicles measuring 18–19 mm at the time of trigger.

Trigger Protocol

Ovulation was triggered using either 10,000 IU of hCG or Ovidrel (recombinant hCG), and oocyte retrieval was performed 36 hours post-trigger. In a subsequent attempt, a double trigger approach combining a GnRH agonist with Gonasi (hCG) was also applied.

Outcome

Despite appropriate hormonal response and follicular development, most of the retrieved oocytes were arrested at the metaphase I (MI) stage. Morphologically, the oocytes were notably characterized by the absence of a perivitelline space.

Genetic Evaluation

Molecular testing for ovarian gene mutations, including TUBB8, was conducted using the Fertiscan™ Global Female Infertility NGS Panel. The panel screened for mutations across a wide range of genes implicated in female reproductive function:
Investigated genes included
ANXA5, BMP15, C4BPA, CAPN10, CD46, CEP250, CGB, CLPP, CYP11A1, CYP17A1, CYP19A1, CYP21A2, DIAPH2, EIF2B2, EIF2B4, EIF2B5, ERCC6, ESR1, ESR2, FANCM, FIGLA, FLJ22792, FMR1 (repeats), FOXL2, FOXP3, FSHB, FSHR, GALT, GDF9, GNRH1, GNRHR, HARS2, HFM1, HLA-G, HSD17B4, IRS1, KHDC3L, KISS1, KISS1R, LARS2, LHB, LHCGR, LHR, MCM8, MCM9, MRPS22, MSH5, NALP7, NLRP10, NOBOX, NR5A1, NUP107, OSBPL5, PADI6, PATL2, PMM2, POF1B, PROKR1, PSMC3IP, SOHLH1, STAG3, SYCE1, SYCP3, TACR3, TLE6, TUBB8, C10orf2, WEE2, WNT6, ZP1, ZP3.
The panel did not reveal any pathogenic variants, including in TUBB8.

Partner Evaluation

The male partner’s semen analysis was within normal parameters.

Analysis of the Case

Case Overview and Clinical Context

The case presented involves a young woman with recurrent oocyte maturation arrest at metaphase I (M1) despite satisfactory estradiol levels and follicle sizes. The genetic analysis for known mutations, including TUBB8, was negative. This suggests a complex issue potentially involving other genetic or physiological factors not yet identified.

This note provides a comprehensive analysis of the provided infertility case, focusing on the consistent arrest of oocytes at metaphase I (M1) during in vitro fertilization (IVF) cycles, and proposes evidence-based treatment solutions. The patient, a 32-year-old woman, has undergone three IVF cycles using antagonist protocols with both urinary and recombinant gonadotrophins, achieving adequate estradiol levels (>2000 pg/ml) and follicle sizes (18-19 mm). Despite various triggers (HCG 10000, Ovidrel, and double trigger with GnRH agonist + GONASI), most oocytes retrieved were arrested at M1, characterized by the absence of perivitelline space. Genetic testing for a comprehensive panel of infertility-related genes, including TUBB8, was negative, and the partner’s sperm analysis was normal.

The patient’s history indicates a persistent challenge in oocyte maturation, with all cycles showing a majority of oocytes failing to progress beyond M1, despite seemingly optimal follicular development and trigger responses. The absence of perivitelline space suggests a potential structural or developmental abnormality, which may impact oocyte viability and fertilization potential. The negative genetic testing, covering genes such as ANXA5, BMP15, and TUBB8 among others, rules out known genetic causes within the tested panel, while the normal sperm analysis eliminates male factor infertility, focusing the issue on the female oocytes.

Potential Causes of Oocyte Maturation Arrest at M1

Oocyte maturation involves the progression from prophase I (germinal vesicle, GV) through metaphase I (M1) to metaphase II (M2), where it is arrested until fertilization. Arrest at M1 indicates a failure to complete the first meiotic division, which can be attributed to several factors:

Intrinsic Oocyte Factors

Research suggests that high levels of cyclic adenosine monophosphate (cAMP) within the oocyte maintain meiotic arrest, and dysregulation can lead to arrest at M1. For instance, studies on rodent oocytes show that GPR3 and adenylate cyclase type 3 (AC3) are crucial for maintaining arrest, and similar mechanisms are likely in humans. If these pathways are disrupted, maturation may stall at M1 [DiLuigi, 2008].

NPPC/NPR2 System Dysregulation

The natriuretic peptide precursor type C (NPPC)/natriuretic peptide receptor 2 (NPR2) system in granulosa cells sustains high cAMP levels by producing cyclic guanosine monophosphate (cGMP), suppressing phosphodiesterase 3A (PDE3A) activity. Dysregulation, such as failure to downregulate with the LH surge, could contribute to arrest [He, 2021].

Epigenetic and Molecular Factors

Histone lysine demethylase KDM1A and DCAF13 (CRL4 adaptor) regulate meiotic progression. Abnormalities in these could impair chromosome condensation and cell cycle progression, leading to M1 arrest [He, 2021].

Structural Abnormalities

The absence of perivitelline space, as noted, may indicate improper oocyte development, potentially affecting gap junction communication with cumulus cells, which is critical for maturation signals (https://en.wikipedia.org/wiki/Oogenesis).

Given the negative genetic testing, the cause may lie in undiscovered genetic variants, epigenetic factors, or environmental influences not captured by the panel, such as exposure to certain substances affecting oocyte quality.

Possible Treatment

Natural Cycle IVF

The absence of perivitelline space in the patient’s oocytes is a notable finding, potentially indicating a developmental abnormality. Research has shown that oocytes with narrow perivitelline space (PVS) have poor fertilization, developmental, and pregnancy potentials. This suggests that the observed absence of PVS could be a significant factor in the patient’s oocyte maturation arrest [Shioya, 2024].

While specific studies comparing perivitelline space in natural versus stimulated cycles are limited, the natural cycle’s physiological environment might better reveal whether this is an intrinsic issue or related to stimulation. Studies have indicated that natural cycles maintain a more favorable follicular environment, which could influence oocyte maturation. For instance, de los Santos et al. (2012) found that the hormonal and molecular environment of follicular fluid and cumulus cells in natural cycles is different from that in stimulated cycles, potentially affecting oocyte competence [de los Santos, 2012].

Furthermore, research on oocyte morphology, such as cumulus expansion, suggests that natural cycles maintain better communication between oocytes and the follicular environment. This bi-directional communication is crucial for oocyte development and maturation, as highlighted by Martinez et al. (2023), who discussed the importance of cumulus-oocyte crosstalk in maintaining oocyte health and developmental competence [Martinez, 2023].

In summary, the natural cycle’s physiological environment might better reveal whether the absence of perivitelline space is an intrinsic issue or related to stimulation, as natural cycles maintain better communication between oocytes and the follicular environment, which could influence maturation.

Exploring oocyte maturation in natural cycles without stimulation could be beneficial for the 32-year-old woman experiencing oocyte maturation arrest at metaphase I. This approach may help determine if the medications used in previous cycles had detrimental effects on oocyte maturation.

Natural cycle IVF (NC-IVF) involves minimal or no ovarian stimulation, relying on the natural selection of a dominant follicle. This method can potentially reduce the exposure to exogenous gonadotropins, which might be contributing to the maturation arrest. Studies have shown that oocyte maturity, fertilization rates, and early-stage embryo morphology can be better in natural cycles compared to high-dose gonadotropin-stimulated cycles. This suggests that the natural follicular environment may support better oocyte development and maturation [Magaton, 2023].

Potential Benefits

This approach might reveal whether the stimulation in previous cycles was affecting maturation or if it’s an intrinsic problem with the oocytes.

Evidence Supporting Natural Cycle IVF for Oocyte Maturation Assessment

Research suggests that natural cycle IVF, especially when combined with IVM, can be a viable approach for patients with oocyte maturation issues in stimulated cycles. Key findings include:

Natural-cycle in vitro fertilization (IVF) combined with in vitro maturation (IVM) of immature oocytes is a potential approach in infertility treatment, particularly for a 32-year-old woman experiencing recurrent oocyte maturation arrest at metaphase I despite satisfactory estradiol levels and follicle sizes, and negative genetic analysis for known mutations including TUBB8.

This approach involves retrieving immature oocytes from small follicles in a natural cycle, followed by their maturation in vitro. This method can be beneficial as it minimizes the exposure to exogenous gonadotropins, which might be contributing to the maturation arrest observed in stimulated cycles.

Key references supporting this approach include [Chian, 2004; Lim, 2009; Yang, 2017; Gilchrist, 2023; Vuong, 2023].

In summary, natural-cycle IVF combined with IVM is a promising approach for patients with recurrent oocyte maturation arrest, offering a less invasive and potentially more effective alternative to conventional stimulated cycles. These studies suggest that natural cycle IVF can provide insights into oocyte maturation without the influence of stimulation protocols, which may disrupt natural processes. The combination with IVM addresses the challenge of immature oocytes, offering a pathway to assess and potentially overcome maturation arrest.

Propose Further Investigation and Treatment

One potential approach is to consider further genetic analysis, such as whole-exome sequencing (WES), which has been shown to identify novel gene-disease associations in cases of oocyte maturation defects. This could uncover rare or novel genetic variants that might be contributing to the oocyte maturation arrest [Capalbo, 2022].

Additionally, the use of a dual trigger with GnRH agonist and hCG has been associated with improved outcomes in terms of oocyte maturation and retrieval rates in some cases [Zhang, 2021].

Although this approach was attempted, it may be worth revisiting the specific protocol, including the timing and dosage of the triggers, as well as considering the addition of adjuvant treatments like growth hormone (GH) or CoQ10, which have shown promise in improving outcomes in poor responders [Zhang, 2020].

Finally, exploring laboratory techniques such as artificial oocyte activation (AOA) with calcium ionophore could be considered, as it may improve fertilization and embryonic development in cases with previous developmental problems. However, these interventions should be tailored to the individual patient’s characteristics and previous responses to treatment [Vuong, 2022].

Analysis and Recommendation

Suggested Treatment

Given the repeated failures, in vitro maturation (IVM) of the M1-arrested oocytes is a promising option. IVM involves culturing immature oocytes to mature them to metaphase II (M2) for fertilization via ICSI. Studies show it can lead to pregnancies and live births, though success rates are lower than standard IVF. For example, one study found a 55.7% fertilization rate for IVM M1 oocytes, with at least one healthy birth, but pregnancy rates were lower (12.4% vs. 33.1% for M2 oocytes) [Álvarez, 2013].

It is recommended to try IVM, using specialized media with FSH, LH/hCG, and other supplements, and performing ICSI 2-6 hours after the first polar body extrusion. Discuss with your doctor the potential for lower success and higher abortion rates, but given your age (32) and the lack of other clear options, it is worth exploring.

IVM Protocols and Considerations

Optimizing in vitro maturation (IVM) for metaphase I (M1) oocytes:

1. Timing of Intracytoplasmic Sperm Injection (ICSI)
   ICSI should be performed 2-6 hours after the extrusion of the first polar body (1PB) to maximize fertilization and embryo development. Delays, such as 23-26 hours, may reduce the number of good-morphology embryos. This is supported by Hyun et al. (2007), who found that fertilization rates were significantly higher when ICSI was performed 1-2, 2-4, 4-6, and 6-8 hours after 1PB extrusion compared to within 1 hour [Hyun, 2007].
2. Culture Conditions
   Use media supplemented with follicle-stimulating hormone (FSH), luteinizing hormone/human chorionic gonadotropin (LH/hCG), epidermal growth factor (EGF)-like growth factors, and antioxidants to mimic in vivo conditions. Biphasic IVM (CAPA-IVM), using C-type natriuretic peptide (CNP) for 24 hours to maintain germinal vesicle (GV) arrest, shows promise for synchronizing maturation. Gilchrist et al. (2024) discussed the use of CAPA-IVM, which involves a pre-IVM phase with CNP to maintain GV arrest, followed by IVM with FSH and EGF-like growth factors, leading to improved oocyte developmental competence [Gilchrist, 2024].
3. Priming
   FSH priming (e.g., 150 IU recombinant FSH for 3 days) and hCG priming can improve oocyte yield and maturation rates, particularly in patients with polycystic ovary syndrome (PCOS). Son and Tan (2010) highlighted that hCG priming permits the recovery of oocytes with an expanded cumulus pattern, facilitating identification and improving IVM rates and embryo development potentials. Additionally, Sánchez et al. (2017) demonstrated that FSH priming followed by IVM using FSH and amphiregulin (AREG) increased oocyte maturation potential and embryo yield in PCOS patients [Son, 2010; Sánchez, 2017].

These references provide a comprehensive overview of the current best practices for optimizing IVM for M1 oocytes.

Conclusion

In vitro maturation of M1-arrested oocytes is the recommended treatment, offering a feasible option given the patient’s history and current evidence. It addresses the maturation arrest directly, with protocols to optimize outcomes, though success rates are lower than standard IVF. The patient should be fully informed of the risks and benefits, and the clinic should ensure expertise in IVM techniques.

The below tables provide a concise and structured overview of the case, investigations, and possible treatment.

Summary of Oocyte Maturation Arrest Case

Parameter	Details
Patient Age	32 years old
Clinical Presentation	Recurrent oocyte maturation arrest at metaphase I (M1) in three IVF cycles
Ovarian Stimulation Protocol	Antagonist protocol with urinary and recombinant gonadotropins
Estradiol Levels	>2000 pg/mL, indicating appropriate hormonal response
Follicular Development	Adequate, with dominant follicles measuring 18–19 mm at trigger
Trigger Protocols	10,000 IU hCG, Ovidrel (recombinant hCG), or double trigger (GnRH agonist + Gonasi hCG)
Outcome	Most oocytes arrested at M1, lacking perivitelline space
Genetic Evaluation	Fertiscan™ NGS Panel (ANXA5, BMP15, TUBB8, etc.); no pathogenic variants found
Partner Evaluation	Normal semen analysis, ruling out male factor infertility

Proposed Further Investigations

Investigation	Purpose	Supporting Reference
Whole-Exome Sequencing (WES)	Identify novel or rare genetic variants causing oocyte maturation arrest	[Capalbo, 2022]
Cumulus-Oocyte Communication Analysis	Assess gap junction functionality and cumulus cell signaling	[Martinez, 2023]
Follicular Fluid Analysis	Evaluate hormonal and molecular environment in natural vs. stimulated cycles	[de los Santos, 2012]

Proposed Treatments

Treatment	Description	Potential Benefits	Supporting Reference
Natural Cycle IVF	Minimal/no stimulation to assess oocyte maturation in physiological environment	May reveal if stimulation affects maturation; better follicular environment	[Magaton, 2023]
In Vitro Maturation (IVM)	Culture M1 oocytes to M2 using specialized media (FSH, LH/hCG, EGF)	Directly addresses M1 arrest; feasible for immature oocytes	[Gilchrist, 2023]
Optimized Dual Trigger	Revisit GnRH agonist + hCG protocol, adjusting timing/dosage	May improve oocyte maturation and retrieval rates	[Zhang, 2021]
Adjuvant Treatments	Add growth hormone (GH) or CoQ10 to improve oocyte quality	May enhance oocyte competence in poor responders	[Zhang, 2020]
Artificial Oocyte Activation	Use calcium ionophore to enhance fertilization	Improves fertilization in cases with developmental issues	[Vuong, 2022]

IVM Protocol Recommendations

Parameter	Recommendation	Supporting Reference
ICSI Timing	2–6 hours after first polar body extrusion	[Hyun, 2007]
Culture Conditions	Media with FSH, LH/hCG, EGF-like factors, antioxidants; consider CAPA-IVM	[Gilchrist, 2024]
Priming	FSH (150 IU for 3 days) and hCG priming to improve oocyte yield/maturation	[Son, 2010; Sánchez, 2017]

Reference List

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2. Capalbo, A., Buonaiuto, S., Figliuzzi, M., et al. (2022). Maternal exome analysis for the diagnosis of oocyte maturation defects and early embryonic developmental arrest. Reproductive BioMedicine Online, 45(3), 508–518. doi:10.1016/j.rbmo.2022.05.009
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