By Aayush Agarwal, Ph.D., Senior Clinical Embryologist Medically reviewed by Dr. Shweta Agarwal, MBBS, DGO Last updated: June 2026
Information on this page is educational and does not replace a medical consultation. Outcomes depend on individual clinical factors.
Aansh Hospital & IVF Center is a government-registered Level-2 ART clinic (Reg. No. MH/AC/2024/15441/L2/Chandrapur/132), part of a growing chain of fertility centers across Vidarbha and northern Telangana. Our headquarters and in-house embryology lab are in Chandrapur. Every step of an IVF cycle — egg retrieval, fertilisation, embryo culture, and transfer — is performed in that lab, not sent to a third-party facility or another city. Our government ART registration covers these activities on-site.
I wrote this guide because the question "is your lab on-site?" is one of the most important things a patient can ask a fertility clinic — and it is not asked often enough. The brochure will almost always look reassuring. What you want to understand is whether the embryology actually happens under the same roof, by a dedicated embryologist, with controlled air and temperature, and with a system that ensures your samples are never confused with anyone else's.
This post explains why each of those things matters, how embryo culture works, and what to ask any clinic before you commit to a cycle.
Why is the embryology lab considered the heart of an IVF cycle?
The embryology lab is where your embryos exist and develop during the most critical and vulnerable period of their early life. From the moment eggs are retrieved, through fertilisation and several days of culture, to the moment of transfer — or freezing — every outcome depends on the quality of the environment those embryos are kept in.
A clinic can have excellent doctors, responsive nurses, and a well-run ward, and still have poor embryology outcomes if the lab environment is inadequate. Conversely, a rigorous lab with experienced embryologists working in a controlled environment gives embryos the best conditions the science currently allows. For patients, understanding that the lab is a separate and critical function — not just a support service — changes the questions you ask.
In India, Level-2 ART clinic registration (under the ART Act 2021) requires that the clinic maintain an on-site embryology lab meeting prescribed standards. The registration number on our certificate can be verified at the National ART & Surrogacy Registry. This is one reason verifying a clinic's government ART registration is a meaningful check rather than a formality.
What environmental factors are embryos sensitive to — and why do they matter?
Embryos developing in culture are exquisitely sensitive to their physical and chemical environment. The parameters that matter most are well-established in reproductive biology:
Temperature — human embryo culture is conducted at 37°C, matching core body temperature. Even modest deviations — a degree or two above or below — can disrupt cellular division. Incubators maintain this range continuously and are monitored for temperature drift.
pH and CO₂ concentration — the culture medium that embryos grow in must be maintained at a physiological pH (approximately 7.2–7.4). pH is regulated by the balance between CO₂ and bicarbonate in the medium. Incubators supply a precisely controlled gas mixture — typically 5–6% CO₂ — to maintain this balance. Fluctuations outside this range stress the embryo at a cellular level.
Oxygen concentration — there is good evidence from reproductive biology that culturing embryos at reduced oxygen (around 5%, approximating the low-oxygen environment of the fallopian tube and uterus) is preferable to ambient air (~21% O₂) for certain embryos. Many modern embryology labs control CO₂, nitrogen, and O₂ simultaneously to maintain this environment.
Air quality and volatile organic compounds (VOCs) — the air inside the lab, and specifically inside the incubators, must be kept free of volatile organic compounds, solvents, cleaning agents, perfumes, and other airborne contaminants. Many of these are toxic to embryos at very low concentrations. This is why IVF labs have strict protocols about what enters the lab and maintain filtered air systems. Staff entering the lab cannot wear scented products.
Light exposure — embryos are sensitive to light, particularly at certain wavelengths. Incubators are designed to keep embryos in the dark except during brief assessments. Microscope illumination during embryo grading is kept to a minimum for this reason.
Time outside the incubator — perhaps the most operationally significant factor: every time an embryo is removed from the incubator — for fertilisation checks, grading, or loading for transfer — it experiences a brief perturbation in temperature, gas, and humidity. Skilled embryologists minimise this time and work efficiently. When a lab is on-site, this is controlled entirely within the team. When embryos must be transported to a different facility, the duration and conditions of that transit become an unavoidable variable.
What does "on-site lab" mean in practice — versus a referred-out lab?
A clinic operating without its own embryology lab must send retrieved eggs and embryos to a third-party laboratory — sometimes in a different part of the city, sometimes in a different city altogether. This is more common than patients realise.
The practical implications of this arrangement include:
Transport. Eggs and embryos must be transported in specialised containers designed to maintain temperature and gas conditions. Even well-designed transport equipment cannot fully replicate the stability of a continuously monitored incubator. Every transfer introduces a period during which conditions are less controlled.
Timing. IVF involves several time-critical steps. ICSI (intracytoplasmic sperm injection) must be performed within a specific window after egg retrieval. Fertilisation checks happen at 16–18 hours post-insemination. Embryo grading is done on schedule. When the lab is in a different location, coordinating these steps involves logistics that add complexity and the potential for delays.
Communication. When the lab and the clinic are separate organisations, communication about embryo status travels between teams. The embryologist who observed your embryos on Day 2 may not be the person who loads the catheter for your transfer. The information chain is longer.
Chain of custody. The moment samples move between facilities, the process of tracking them must work across two organisations. This adds handoff points.
When the lab is on-site, all of these issues are contained within one team, one set of protocols, and one physical space. The embryologist who performed ICSI on your eggs is the same person who grades the embryos on Day 3 and prepares them for transfer. There is no external logistics step.
How does specimen witnessing work — and why is it the thing patients worry about most?
The single most common anxiety patients raise about IVF labs is this: how do I know my eggs, sperm, and embryos will not be mixed up with someone else's?
This is an entirely reasonable concern. An IVF lab handles multiple patients' samples simultaneously. The consequences of a mix-up are profound and irreversible.
The answer is a process called specimen witnessing (sometimes called a witness system or double-check system). At each handling step — labelling a dish, loading sperm for ICSI, assigning embryos to culture wells, loading a transfer catheter — the sample identification is independently verified. This can be done by a second person checking the label, or by an electronic verification system that cross-checks patient identifiers against barcoded sample containers at each step.
In a well-run on-site lab, this chain is unbroken within one facility. Every dish, every tube, every catheter carries the patient's identifier, checked at each step against the electronic record or verified by a second staff member.
The ART Act 2021 and the ICMR guidelines for ART clinics require robust sample identification and documentation as part of the minimum standards for a registered lab. When you ask a clinic about its witnessing process, you are asking about a regulatory requirement, not an optional quality feature.
If a clinic cannot explain its witnessing protocol clearly, that is worth noting. A competent embryology team will be able to describe their process directly.
What happens during embryo culture — days one to five or six?
After fertilisation (whether by standard IVF or ICSI), the fertilised egg — now a zygote — is placed in a culture dish with specialised culture medium and transferred to the incubator. Over the next several days, it undergoes a series of cell divisions.
Day 1 (16–18 hours post-insemination): Fertilisation check. A normally fertilised egg shows two pronuclei (2PN) — one from the egg and one from the sperm. This is the first quality checkpoint.
Day 2–3: The embryo divides progressively — typically reaching 4 cells by Day 2 and 8 cells by Day 3. The embryologist assesses cell number, symmetry, and the presence of fragmentation (cellular debris). This is what is meant by Day-3 or cleavage-stage grading. In Marathi and Hindi, this early embryo stage is sometimes referred to as भ्रूण (bhroon) — the same word used in embryology discussions in Vidarbha clinics.
Day 4: The embryo undergoes compaction to form the morula — the cells begin to fuse together, forming a compact ball.
Day 5–6: The morula develops into a blastocyst — a structure with a fluid-filled cavity (blastocoel), an outer layer of cells (trophectoderm, which will become the placenta), and an inner cell mass (which will become the fetus). Blastocyst development is a meaningful quality indicator because it requires the embryo to sustain several rounds of coordinated gene expression. Embryos that do not have sufficient developmental competence typically arrest before reaching the blastocyst stage.
Blastocyst culture — culturing embryos to Day 5 or 6 before transfer or freezing — allows the embryologist to select embryos that have demonstrated a higher level of developmental competence. It also improves the synchronisation between embryo and uterine lining for frozen embryo transfers. The decision to culture to blastocyst is made based on the number of embryos and their Day-3 quality.
A detailed explanation of how embryos are graded — including the Gardner grading system for blastocysts — will be covered in a forthcoming post at /blog/understanding-embryo-grading.
What is ICSI, and why does the embryologist's skill matter at this step?
ICSI (intracytoplasmic sperm injection) is the step where a single sperm is selected and injected directly into a mature egg using a fine glass needle and a micromanipulator. It is used for male-factor infertility, previously poor fertilisation with standard IVF, or when sperm have been surgically retrieved.
The skill of the embryologist performing ICSI matters in several ways. First, sperm selection — identifying morphologically normal, progressively motile sperm from a prepared sample requires experience and careful assessment under high-power microscopy. Second, the injection technique itself — the angle, depth, and speed of needle insertion, and the release of the sperm into the egg cytoplasm — requires precise micromanipulation to avoid damaging the egg. Third, the management of the entire procedure under time pressure — ICSI must be completed within a defined window after egg retrieval — requires both technical proficiency and efficient lab workflow.
When the lab is on-site, there is no logistical gap between egg retrieval and the embryologist beginning ICSI. The eggs are denudated (their surrounding cumulus cells removed), assessed for maturity, and injected in a single coordinated session in the same lab. Every hour matters at this step.
What questions should you ask any IVF clinic about its lab?
Whether you are consulting at Aansh or anywhere else, these are the direct questions worth asking before committing to a cycle:
1. Is your embryology lab on-site, or are eggs and embryos sent to a third-party laboratory? A clear yes or no. If the answer involves any variation of "it depends" or "we work with a partner lab," ask specifically where your embryos will be cultured.
2. Who is the embryologist, and are they present for every cycle? Ask for the name and qualifications of the embryologist who will perform ICSI and daily embryo grading on your cycle. Ask whether a different embryologist might step in, and what the continuity protocol is.
3. What is your specimen witnessing protocol? How does the lab verify that each sample — dish, catheter, tube — is matched to the correct patient at each step? Is this manual double-checking, an electronic system, or both?
4. What air quality controls does the lab have? Is there HEPA and activated-carbon filtration? What is the protocol for VOC control?
5. What incubators are used, and are they individually cleaned and calibrated per patient? Some labs use large shared incubators; others use small benchtop units where each patient's embryos are in a separate, individualised chamber with stable gas concentrations.
6. Can I see the lab, or at least the lab area, during my consultation visit? Most regulated IVF labs cannot allow patients to walk through the active lab space (sterility reasons), but being shown the lab through a window or shown photographs of the setup is reasonable. A clinic that is confident in its lab will generally be happy to show it.
7. What is the clinic's ART registration number, and can I verify it? In India, Level-2 ART registration is a government-issued credential that can be checked on the National ART & Surrogacy Registry. For Aansh: Reg. No. MH/AC/2024/15441/L2/Chandrapur/132. You can verify this registration directly.