Embryology Q&A by Sule Dogan PhD HCLD/ CC (ABB)
Q: What is the fertilization success rates with ICSI and why do not all eggs get fertilized with ICSI?
A: The overall fertilization rate should be more than 80% in an ICSI cycle, but this rate is higher if any donor oocytes are used in the cycle, or it might be lower depending upon the patient profile. There might be many reasons for fertilization failure in an IVF /ICSI cycle. Two main reasons would be the oocyte maturation abnormalities that are negatively affected by maternal age and suboptimal semen parameters such as non-obstructive azoospermia and sperm morphological defects. It is very rare, but sometimes (1-3 % of ICSI cycles and 5-10% of IVF cycles) none of the mature oocytes get fertilized after IVF/ ICSI, this phenomenon is called total fertilization failure (TFF). Fertilization failure might be caused by oocytes activation deficiency (OAD) where oocyte activation is failed due to certain mutation in either sperm or oocyte. Some of those well-known mutations are phospholipase C zeta (PLCζ), PLCZ1 mutations, wee1-like protein kinase 2 (WEE2) mutations, PAT1 homolog 2 (PATL2) mutations, tubulin beta-8 chain (TUBB8) mutations, and transducin-like enhancer protein 6 (TLE6) mutations.
Q: How common are Day 6 or 7 blastocysts? Can they still produce a successful outcome?
A: Preimplantation genetic testing for aneuploidy (PGT-A) screens embryos for numerical chromosomal abnormalities. Genetically tested embryos have a better chance of implantation capability compared to not tested embryos. Although clinical pregnancy is lower with the Day 7 blastocyst (13.9%) in non-PGT cycles, this goes up to 41.7% when an Euploid Day 7 blastocyst is transferred. Recent studies showed that pregnancy rates are comparable with Day 5 and Day 6 blastocysts in PGT cycles. Clinical outcomes are affected by patient age, BMI, endometrial thickness, and embryo’s inner cell mass grading (ICM) rather than biopsy day. In non-PGT cycles, the data support the selection of day 5 blastocysts for transfer over day 6 blastocysts.
Q: Is there anything that can help get PGTA normal embryos after multiple rounds without success?
A: Preimplantation genetic testing for aneuploidy (PGT-A) only screens embryos for numerical chromosomal abnormalities. According to the current literature, Euploidy rate in embryos is positively related to AMH levels and negatively related to female age. Using microfluid sperm sorting or PICSI dish with hyaluronic acid binding assay to improve Euploidy rates is still controversial. However, these methods may be used for cases with severe male factor infertility or advanced paternal age as an alternative. Donor oocytes may be another alternative to achieve pregnancy in cases with previous multiple IVF failures.
Q: What is the difference between PICSI and Zymot?
A: Both PICSI and Zymot are sperm selection devices in IVF/ICSI cycles. PICSI is a dish with Hyaluronan microdots where mature sperm will bind to hyaluronan so that they can be selected and used for ICSI. Zymot is a microfluidic device that sorts motile and morphologically normal sperm from a raw sample without centrifugation.
Although there are studies supporting clinical use of both devices in IVF / ICSI cycles, the current literature is controversial if these devices improve the pregnancy outcome while they increase the cost of a cycle. According to a study, both fertilization rates and transfer eligible embryo rates were significantly higher in PICSI fertilized oocytes compared to their ICSI counterparts. However, another study found that there were no statistically significant differences between ICSI vs PICSI groups in clinical pregnancy rates. Based on the findings of a study, Zymot decreased sperm DNA fragmentation and increased the implantation and clinical pregnancy rates. Contrarily, Molly et al., showed that there were no differences found in the clinical pregnancy or ongoing pregnancy rates between Zymot vs routine sperm selection method.
Q: How to improve getting healthy embryos with MFI?
Male factor infertility (MFI) is responsible for 30% to 50% of all cases of infertility. Male infertility may be caused by endocrine, physiological and testicular disorders as well as, environmental and genetic problems. Male infertility can also be classified as pre-testicular, testicular and post-testicular. Male infertility can be diagnosed by semen analysis where sperm parameters are evaluated and other tests such as hormonal tests and genetic tests. Based on the cause of male infertility, clinicians may be able to treat the underlying cause. The most common assisted reproductive technologies to treat male infertility is intracytoplasmic sperm injection (ICSI). Another procedure for male factor infertility patients is to retrieve sperm surgically via testicular sperm aspiration (TESA) if there is no sperm in the semen. Depending upon the cause of infertility, preimplantation genetic testing for Aneuploidy (PGT-A) can be included in the treatment plan to have genetically normal (healthy) embryos for transfer. The recent guideline published by American Urological Association (AUA) and American Society for Reproductive Medicine (ASRM) outlines the management and treatment of male infertility in IVF/ICSI cycles for clinicians.
Q: Is 3 flagged genetic diseases in a carrier screening test worring for embryos normality?
A: It depends on the genetic diseases that are flagged in the carrier screening. Genetic diseases may or may not be a risk factor in pregnancy and in embryo development. We know that some genetic diseases or mutations can be lethal when inherited while some do not impact embryo development. The American College of Obstetricians and Gynecologists (ACOG) recommends that carries screening for Spinal Muscular Atrophy and Cystic Fibrosis should be offered to all women who are considering pregnancy or currently pregnant. If any of the patients are carriers of any genetic diseases, then preimplantation genetic testing for monogenic diseases (PGT-M) should be discussed. Genetically normal i.e., Euploid and Unaffected embryos can be detected by using PGT-M technology in IVF/ICSI cycles where a few cells are biopsied from an embryo and tested for a specific gene disease by using next-gene sequencing (NGS) technologies. This PGT-M technique has been successfully used for sickle cell disease and most types of β-thalassemia patients. It is strongly recommended to get genetic counseling regarding the risks of those flagged genetic diseases.
Q: Can TESE be a solution for couples who have a problem getting embryos to blastocyst?
A: Yes and No! Blastocyst formation is affected by many factors such as oocyte related issues and sperm related problems. Testicular sperm aspiration has been successfully used in men with both obstructive and non-obstructive azoospermia for many years. Studies showed that the clinical outcomes, including fertilization and blastocyst rates are comparable between ICSI cycles using testicular and ejaculated sperm. In 2013, another study suggested that the ICSI cycles with testicular sperm have better fertilization and pregnancy rates compared to the ones with ejaculated sperm when the embryo transfers were done on Day 3. However, a latest study published in 2021 showed that using testicular sperm over ejaculated sperm in patients with non-azoospermia such as patients with low sperm concentration (oligozoospermia) did not improve fertilization, blastocyst, miscarriage and live birth rates.
Q: How long does schooling for this take?
A: Embryology is a very unique field where both reproductive biology and clinical lab sciences meet. Embryologists work with physicians, nurses and patients closely on a daily basis. Although there are master’s programs in clinical embryology, these programs offer limited hands-on experience. Embryologists usually enhance their skills during their orientation in fertility clinics over the years or attend training programs by private companies or workshops and conferences by the American society of reproductive medicine (ASRM). To work as an Embryologist, one must have to obtain a minimum of a bachelor’s degree in medical, laboratory and life sciences and a minimum of three to four years of clinical IVF laboratory experience or a master’s degree in Reproductive Science and two years of IVF lab experience or PhD degree in biological and reproductive sciences and a year of IVF lab experience. Some states require licensing and certification, which are similar to medical technologist or medical laboratory scientists certifications.
There are online master’s and PhD programs by Eastern Virginia Medical School. https://www.evms.edu/education/masters_programs/reproductive_clinical_science_masters_program/
There are also hands-on certificate courses by private companies such as ART lab, IVF Academy USA, Ovatools, and WEST.
- Campos G, Sciorio R, Esteves SC. Total fertilization failure after ICSI: insights into pathophysiology, diagnosis, and management through artificial oocyte activation. Hum Reprod Update. 2023 Jul 5;29(4):369-394. doi: 10.1093/humupd/dmad007. PMID: 36977357.
- Abdala A, Elkhatib I, Bayram A, Arnanz A, El-Damen A, Melado L, Lawrenz B, Fatemi HM, De Munck N. Day 5 vs day 6 single euploid blastocyst frozen embryo transfers: which variables do have an impact on the clinical pregnancy rates? J Assist Reprod Genet. 2022 Feb;39(2):379-388. doi: 10.1007/s10815-021-02380-1. Epub 2022 Jan 22. PMID: 35064434; PMCID: PMC8956773.
- Tong J, Niu Y, Wan A, Zhang T. Comparison of day 5 blastocyst with day 6 blastocyst: Evidence from NGS-based PGT-A results. J Assist Reprod Genet. 2022 Feb;39(2):369-377. doi: 10.1007/s10815-022-02397-0. Epub 2022 Jan 10. PMID: 35013836; PMCID: PMC8956767.
- Liu X, Lou H, Zhang J, Du M, Du Y, Wu S, Guan Y, Liu J. Clinical outcome analysis of frozen-thawed embryo transfer on Day 7. Front Endocrinol (Lausanne). 2022 Dec 9;13:1082597. doi: 10.3389/fendo.2022.1082597. PMID: 36568064; PMCID: PMC9780262.
- LA Marca A, Capuzzo M, Imbrogno MG, Donno V, Spedicato GA, Sacchi S, Minasi MG, Spinella F, Greco P, Fiorentino F, Greco E. The complex relationship between female age and embryo euploidy. Minerva Obstet Gynecol. 2021 Feb;73(1):103-110. doi: 10.23736/S2724-606X.20.04740-1. Epub 2020 Dec 11. PMID: 33306288.
- Keskin M, Pabuçcu EG, Arslanca T, Demirkıran ÖD, Pabuçcu R. Does Microfluidic Sperm Sorting Affect Embryo Euploidy Rates in Couples with High Sperm DNA Fragmentation? Reprod Sci. 2022 Jun;29(6):1801-1808. doi: 10.1007/s43032-021-00784-z. Epub 2021 Nov 3. PMID: 34731459.
- Godiwala P, Almanza E, Kwieraga J, Makhijani R, Grow D, Nulsen J, Benadiva C, Bartolucci A, Engmann L. Embryologic outcomes among patients using a microfluidics chip compared to density gradient centrifugation to process sperm: a paired analysis. J Assist Reprod Genet. 2022 Jul;39(7):1523-1529. doi: 10.1007/s10815-022-02504-1. Epub 2022 May 27. PMID: 35619041; PMCID: PMC9365916.
- Novoselsky Persky M, Hershko-Klement A, Solnica A, Bdolah Y, Hurwitz A, Ketzin El Gilad M, Nefesh I, Esh-Broder E. Conventional ICSI vs. physiological selection of spermatozoa for ICSI (picsi) in sibling oocytes. Andrology. 2021 May;9(3):873-877. doi: 10.1111/andr.12982. Epub 2021 Feb 17. PMID: 33523582.
- Emirdar V, Karatasli V, Tamer B, Pala I, Gunturkun F, Ozbaykus C, Işık AZ, Gode F. Influence of a hyaluronan-binding system for sperm selection in intracytoplasmic sperm injection cycles on embryo morphokinetic parameters and in vitro fertilization cycle outcomes. Arch Gynecol Obstet. 2023 May;307(5):1633-1639. doi: 10.1007/s00404-023-06992-z. Epub 2023 Mar 9. PMID: 36892604.
- Le MT, Nguyen HTT, Van Nguyen T, Nguyen TTT, Dang HNT, Dang TC, Nguyen QHV. Physiological intracytoplasmic sperm injection does not improve the quality of embryos: A cross-sectional investigation on sibling oocytes. Clin Exp Reprod Med. 2023 Jun;50(2):123-131. doi: 10.5653/cerm.2023.05918. Epub 2023 May 23. PMID: 37258106; PMCID: PMC10258512.
- Molly M Quinn and others, Microfluidic preparation of spermatozoa for ICSI produces similar embryo quality to density-gradient centrifugation: a pragmatic, randomized controlled trial, Human Reproduction, Volume 37, Issue 7, July 2022, Pages 1406–1413,
- Kocur, OM, Xie, P, Cheung, S, et al. Can a sperm selection technique improve embryo ploidy?Andrology. 2022; 1-8. https://doi.org/10.3390/reprodmed20300
- Leslie SW, Soon-Sutton TL, Khan MAB. Male Infertility. 2023 Mar 3. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan–. PMID: 32965929.
- Schlegel PN, Sigman M, Collura B, De Jonge CJ, Eisenberg ML, Lamb DJ, Mulhall JP, Niederberger C, Sandlow JI, Sokol RZ, Spandorfer SD, Tanrikut C, Treadwell JR, Oristaglio JT, Zini A. Diagnosis and treatment of infertility in men: AUA/ASRM guideline part I. Fertil Steril. 2021 Jan;115(1):54-61. doi: 10.1016/j.fertnstert.2020.11.015. Epub 2020 Dec 9. PMID: 33309062.
- Ben-Ami I, Raziel A, Strassburger D, Komarovsky D, Ron-El R, Friedler S. Intracytoplasmic sperm injection outcome of ejaculated versus extracted testicular spermatozoa in cryptozoospermic men. Fertil Steril. 2013 Jun;99(7):1867-71. doi: 10.1016/j.fertnstert.2013.02.025. Epub 2013 Mar 13. PMID: 23490166.
- Lee SH, Park CW, Cheon YP, Lim CK. Potential of testicular sperm to support embryonic development to the blastocyst stage is comparable to that of ejaculated sperm. J Assist Reprod Genet. 2018 Jun;35(6):1103-1111. doi: 10.1007/s10815-018-1191-8. Epub 2018 May 5. PMID: 29728797; PMCID: PMC6030020.
- Kendall Rauchfuss LM, Kim T, Bleess JL, Ziegelmann MJ, Shenoy CC. Testicular sperm extraction vs. ejaculated sperm use for nonazoospermic male factor infertility. Fertil Steril. 2021 Oct;116(4):963-970. doi: 10.1016/j.fertnstert.2021.05.087. Epub 2021 Jul 4. PMID: 34233843.