At a glance
Embryologists are the laboratory specialists who handle eggs, sperm, and embryos during IVF. In Thailand, their duties include fertilization, embryo culture, grading, biopsy for PGT, and cryopreservation.
When you undergo IVF in Thailand, much of the treatment happens outside your body—in the embryology laboratory. The embryologist is the specialist who handles your eggs, sperm, and embryos with precision and care. Their role is critical to the success of your cycle, from the moment eggs are retrieved to the day embryos are transferred or frozen.
This article explains the key duties of an embryologist in an IVF setting, with a focus on procedures relevant to preimplantation genetic testing (PGT). Whether you are considering PGT or simply want to understand the lab process, knowing what an embryologist does can help you feel more informed and confident.
At a Glance: Embryologist Responsibilities
- Fertilization: Combining eggs and sperm (IVF or ICSI) to create embryos.
- Embryo culture: Maintaining embryos in optimal conditions for growth.
- Embryo grading: Assessing embryo quality based on morphology and development.
- Biopsy for PGT: Removing cells from embryos for genetic analysis.
- Cryopreservation: Freezing embryos, eggs, or sperm for future use.
Fertilization: Creating Embryos in the Lab
After egg retrieval, the embryologist identifies and isolates mature eggs. Fertilization can occur in two ways:
- Conventional IVF: Eggs and sperm are placed together in a dish, allowing sperm to fertilize eggs naturally.
- Intracytoplasmic Sperm Injection (ICSI): A single sperm is injected directly into each mature egg. ICSI is commonly used when sperm quality is low or when PGT is planned, to reduce the risk of contamination from excess sperm.
The embryologist monitors fertilization the next day, looking for two pronuclei (visible structures) that indicate successful fertilization.
Embryo Culture: Supporting Development
Fertilized eggs (now embryos) are placed in specialized culture media that provide nutrients and support growth. The embryologist maintains strict control over temperature, humidity, and gas composition (oxygen and carbon dioxide) to mimic the natural environment of the fallopian tubes and uterus.
Embryos are typically cultured for 5–6 days until they reach the blastocyst stage, which is the stage most suitable for transfer, biopsy, or freezing. The embryologist checks embryos daily to track development and remove any that are not growing normally.
Embryo Grading: Assessing Quality
Embryo grading is a non-invasive assessment of embryo quality based on visual characteristics. The embryologist uses a microscope to evaluate:
- Cell number and symmetry (for cleavage-stage embryos on day 2–3).
- Expansion and hatching status (for blastocysts on day 5–6).
- Inner cell mass (ICM) quality – the part that becomes the fetus.
- Trophectoderm (TE) quality – the part that becomes the placenta.
Grading helps prioritize which embryos to transfer, biopsy, or freeze. However, grade alone does not guarantee genetic normality or pregnancy potential.
Biopsy for PGT: Removing Cells for Genetic Testing
If you are planning preimplantation genetic testing (PGT), the embryologist performs a biopsy on the embryo. This is typically done at the blastocyst stage (day 5 or 6).
The embryologist uses a laser or a fine needle to remove a small number of cells from the trophectoderm (the outer layer). These cells are sent to a genetics laboratory for analysis. The embryo itself is then frozen (vitrified) while awaiting results.
Biopsy is a delicate procedure that requires skill to minimize potential damage to the embryo. The embryologist must ensure that enough cells are collected for reliable testing without compromising the embryo’s viability.
Cryopreservation: Freezing Embryos for Future Use
Embryos that are not transferred in the fresh cycle—whether because they are being tested, or because you choose to freeze them—are cryopreserved. The embryologist uses a rapid freezing technique called vitrification, which prevents ice crystal formation and helps maintain embryo survival after thawing.
Frozen embryos can be stored for months or years and used in a later frozen embryo transfer (FET) cycle. The embryologist also handles the thawing process when you are ready to use them.
Questions to Ask Your Clinic About the Embryology Lab
- What is the experience level of the embryologists at your clinic?
- Do you use time-lapse imaging for embryo monitoring?
- What is your policy on embryo grading and how is it communicated to patients?
- How many cells are typically biopsied for PGT, and what is your success rate for biopsy?
- What vitrification method do you use, and what is your survival rate for frozen embryos?
Next Steps for Patients
- Ask your clinic about their embryology team’s qualifications and experience.
- Discuss whether ICSI is recommended for your case, especially if PGT is planned.
- Inquire about the lab’s quality control measures and accreditation.
- Review your consent forms to understand how embryos are handled and stored.
For more information on PGT in Thailand, visit our PGT in Thailand page. You can also explore our guides and FAQ for additional insights.
Frequently asked questions
What qualifications do embryologists in Thailand have?
Embryologists in Thailand typically hold a bachelor's or master's degree in reproductive biology, embryology, or a related field. Many have additional training and certification from international bodies. You can ask your clinic about the specific qualifications of their embryology team.
How long does it take for an embryologist to culture embryos before transfer?
Embryos are usually cultured for 5–6 days until they reach the blastocyst stage. The exact timing depends on the embryo's development and the treatment plan. Your clinic will provide a schedule based on your cycle.
Is embryo biopsy safe for the embryo?
Embryo biopsy is a delicate procedure, but when performed by an experienced embryologist, the risk of damage is low. Studies suggest that biopsied embryos have similar implantation potential to non-biopsied embryos, but individual outcomes vary. Discuss the risks and benefits with your clinic.
Can the embryologist tell if an embryo is genetically normal just by looking at it?
No. Embryo grading assesses morphology only and cannot determine genetic normality. PGT is required to identify chromosomal abnormalities or specific genetic conditions.
What happens to embryos that are not suitable for transfer or freezing?
Embryos that are not viable or of poor quality may be discarded or used for research with your consent. Your clinic will explain the options and ask you to sign a consent form specifying your preferences.
Continue your research
Medical information notice: This article is educational and does not replace individual assessment, diagnosis, genetic counselling or treatment advice from a licensed clinician. Provider services, availability, fees and policies should be verified directly before booking.
Need help turning research into a shortlist?
