IVF News

Why Secure Liquid Nitrogen Supply Matters for IVF 

For IVF clinics and fertility centrers, access to liquid nitrogen is crucial for the long-term protection of embryos, oocytes and sperm that represent future treatment opportunities for patients and their families. 

Maintaining the integrity of cryopreserved reproductive materials depends on stable storage conditions, making liquid nitrogen (LN₂) a critical part of IVF laboratory operations. Any disruption to the supply chain can place valuable samples at risk, putting pressure on embryology teams responsible for storage management and regulatory compliance.

Demand for fertility treatment has been growing with Asia-Pacific consistently identified as the fastest-growing region, while Europe and North America continue to capture the largest total market share. (1) 

Supply chain vulnerabilities, rising transportation costs and strict compliance madates are driving self-sufficiency and the adoption of on-site/plug-and-play liquid nitrogen generation systems.

The Challenge of Delivered Supply

Most IVF clinics rely on delivered liquid nitrogen to maintain cryogenic storage vessels and vapour phase storage systems. While this has traditionally been the established model, it can introduce vulnerabilities that are outside the clinic's control.

Unexpected factors such as supplier shortages, severe weather, rising demand, production outages, or increasing delivery costs can affect the price and availability of liquid nitrogen. For laboratories responsible for preserving thousands of embryos, oocytes and sperm samples, maintaining continuity of supply is essential.

Why Liquid Nitrogen Reliability Matters in IVF

Cryopreservation is central to modern assisted reproductive technologies (ART). The success of these programmes depends upon maintaining cryogenic temperatures throughout the storage lifecycle. While storage tanks are designed to provide thermal protection, they still require regular replenishment with liquid nitrogen.

A dependable supply strategy helps IVF clinics minimize operational risk, maintain confidence in storage systems and ensure continuity for patients who may rely on preserved reproductive material months or even years into the future.

Benefits of On-Site LN₂ Generation for IVF Clinics

To improve supply security, an increasing number of life science and healthcare facilities are turning to on-site liquid nitrogen generation.

Rather than depending entirely on bulk deliveries, a liquid nitrogen generator placed on-site enables clinics to generate liquid nitrogen directly at their facility, providing a continuous source of cryogen for storage applications. Generators can be matched to the required production output and are able to create liquid nitrogen from atmospheric air.

Using a liquid nitrogen generator comes with several benefits:

• Enhanced Supply Security
  • By producing LN₂ on-site, clinics can significantly reduce their exposure to external supply chain disruptions.
  • Whether faced with a delivery delay, supplier pressure or unexpected demand fluctuations, facilities retain greater control over the availability of liquid nitrogen needed to support biostorage operations.
• Improved Operational Resilience
  • On-site generation can provide additional assurance for facilities storing high-value reproductive material. A local source of liquid nitrogen helps support business continuity planning and can form an important part of a broader cryostorage risk management strategy.
• Reduced Administration&Planning
  • Traditional supply models require ongoing coordination of liquid nitrogen deliveries, storage management and inventory monitoring.
  • Generating LN₂ on-site reduces reliance on scheduled deliveries and simplifies long-term supply planning, particularly for facilities with growing storage requirements.
• Greater Cost Predictability
  • Although delivered liquid nitrogen costs can fluctuate due to transport, energy and supply chain factors, on-site generation can provide a more predictable long-term operating model. This allows clinics to better forecast future costs.

Supporting the Future of Fertility Preservation

Demand for fertility preservation and long-term cryogenic storage continues to increase as reproductive technologies advance and more patients choose to preserve reproductive material for future use.

As storage inventories grow, ensuring a secure, dependable supply of liquid nitrogen becomes increasingly important.

For IVF clinics seeking to strengthen operational resilience, improve supply security and reduce dependence on external deliveries, on-site liquid nitrogen generation offers an effective solution. By bringing production closer to the point of use, fertility centres can support the safe, continuous storage of the reproductive material entrusted to their care.

The insulation is an absence

There is no insulating material within the wall of a vacuum insulated vessel. The annular space between the inner and outer vessels is evacuated and sealed, and that vacuum performs the insulating function.

Heat reaches the contents by conduction, convection and radiation. Evacuation largely eliminates convection, since the mechanism requires a gas as a medium. Conduction is restricted to what the neck, supports and pipework must structurally carry. Radiation is addressed separately.

The operational implication deserves emphasis. Because convection has been removed rather than reduced, a vessel that loses vacuum does not decline gently. A transport path the design eliminated has been restored, and performance falls accordingly.

Multilayer insulation

Radiation is addressed by multilayer insulation, comprising many alternating layers of reflective film and low conductivity spacer wrapped around the inner vessel. The reflective layers return radiant heat and the spacers prevent contact between them, since two reflective layers in contact constitute a conduction bridge.

Larger bulk vessels commonly use perlite within the annulus instead, a fine expanded volcanic glass powder, also under vacuum. The distinction is relevant at service time, because a perlite filled annulus cannot be opened, re-wrapped and evacuated on site in the manner possible with some smaller vessels.

The getter, and why service life is finite

A sealed vacuum does not remain perfect. Materials within the annulus outgas slowly over a period of years, and hydrogen and helium migrate through steel, which is a property of the material rather than a defect of manufacture.

Manufacturers therefore incorporate a getter, a chemically active material that absorbs stray gas molecules, sometimes accompanied by an adsorbent performing the equivalent function at cryogenic temperature.

Getter capacity is finite, and this is the principal determinant of a vessel's service life. On saturation, annulus pressure rises progressively and thermal performance declines with it. No component fails, no alarm condition arises and no visible change occurs. The failure is inferred from consumption rather than observed directly.

For units operating under the current 55 year storage limit, this has a planning consequence. Samples will outlive several generations of vessel, which makes transfer between vessels a recurring, documented operation rather than an exceptional event.

Specifying on the correct figure

The comparator between vessels is the static evaporation rate, also termed the normal evaporation rate or NER, expressed as litres per day or as a percentage of capacity per day and measured with the vessel closed and undisturbed under defined conditions.

A larger vessel with a poor rate can carry a higher running cost than a smaller vessel with a good one, so comparison on capacity alone is misleading.

Equally, the manufacturer figure should be treated as a laboratory baseline and not as a prediction for a working store. Every lid lift, every cane retrieval and every warm object introduced adds heat that the measurement excludes. A busy clinical store operating at several multiples of its static rate is behaving normally rather than indicating a fault.

Three further questions are worth putting at procurement: what the warranty covers specifically in respect of the vacuum, since that is the component that determines service life; what the end of life position is, since a saturated getter is not a repair on most designs; and what neck diameter is offered, since a wide neck eases retrieval while increasing heat ingress, and the appropriate compromise depends on access frequency.

Recognising vacuum loss in service

Frost or condensation appearing on a previously dry outer shell, typically first near the base or around a support point, is the clearest indicator. Any cold spot on an external surface that should be at ambient temperature indicates conduction through the annulus.

Less conspicuous indicators include consumption rising steadily across months at unchanged workload, hold time falling below the same vessel's performance in the previous year, and altered behaviour following a drop, impact or rough transport, since mechanical shock can crack a weld or fracture an internal support without external evidence.

A degrading vacuum does not recover and the rate of deterioration increases once established. Contents should be transferred and the vessel withdrawn from service rather than monitored in place.

The practical monitoring recommendation is therefore to establish a consumption baseline in litres per week under local conditions and workload, and to treat sustained upward drift as the actionable signal. It typically precedes visible frosting by a considerable margin.

Standards

The BS EN 13458 series covers static vacuum insulated vessels across three parts: fundamental requirements; design, fabrication, inspection and testing; and operational requirements.

BCGA Code of Practice 36 addresses cryogenic liquid storage at users premises, including the safety device arrangement and the requirement for a written scheme of examination under the Pressure Systems Safety Regulations 2000 where a vessel operates above 0.5 bar gauge.

Open neck storage dewars of the type used for sample banking are vented to atmosphere and generally fall outside the pressure regime. They remain vacuum insulated vessels, and the degradation behaviour described above applies to them without qualification.

Full article: https://cryolab.co.uk/vacuum-insulated-cryogenic-storage-tanks/

Consent documentation across the sector was revised within weeks. Storage estates, in most units, were not revised at all. A vessel specified against a ten year horizon is now expected to hold samples for a period exceeding the working career of most of the staff who will handle them.

Capacity planning has changed regime

Under the previous limit, storage was substantially self clearing. Samples left at a rate that approximated intake, and capacity planning was a rolling exercise conducted against a broadly stable inventory.

Under the current limit, outflow reduces to a trickle and inventory accumulates. Any model carried forward from before July 2022 is calibrated on behaviour that no longer applies, and honest modelling of intake against withdrawal typically indicates a requirement for additional capacity considerably earlier than current vessel counts imply.

Vessel service life is now a clinical governance matter

A vacuum insulated storage vessel does not last 55 years.

The insulating element is an evacuated annulus, and that vacuum is maintained by a getter, a chemically active material with finite capacity that absorbs gas released by outgassing and by permeation through the vessel wall. On saturation, annulus pressure rises, thermal performance declines, and no component fails, no alarm condition arises and nothing visibly breaks.

The consequence for a unit operating under a 55 year retention window is that stored samples will outlive several generations of vessel. Transfer between vessels therefore becomes a planned, repeated and documented operation rather than an exceptional event associated with equipment failure.

Each transfer is a warming exposure, which makes the next point material.

The risk band is not ambient temperature

Below approximately -130°C, biological material occupies the glassy state. Molecular motion has effectively ceased and degradative reactions have stopped. A blastocyst warmed after twenty years carries the biological age it held at the point of freezing.

The region of concern lies between approximately -130°C and -80°C, where molecular motion has resumed while the sample remains visually frozen. Ice recrystallisation occurs within this band, and it is both cumulative across exposures and undetectable at the time.

A sample that spends thirty seconds longer than intended in warm vapour during a routine retrieval yields no indication of the fact. The damage is recorded in the sample and not in the laboratory record, which means transfer and retrieval technique should be understood as storage variables rather than purely as handling matters.

For units now anticipating repeated transfers across decades, this argues for treating transfer as a defined procedure with its own standard operating procedure, timing discipline and audit trail, rather than as an ad hoc task performed when a vessel is replaced.

Vitrification relocated risk rather than removing it

Slow controlled rate freezing reduces temperature at a programmed rate, typically a fraction of a degree per minute, permitting gradual dehydration of the cell under a relatively low concentration of cryoprotectant. Vitrification employs a very high cryoprotectant concentration in minimal volume, cooling at a rate sufficient to traverse the crystallisation range without ice formation.

Vitrification has largely displaced slow freezing for oocytes and embryos in routine practice. The accompanying shift in risk profile is less frequently stated. Slow freezing was equipment dependent and comparatively tolerant of operator variation. Vitrification is the inverse: loading volume, exposure time in the cryoprotectant and the interval between removal from media and plunging are operator controlled and measured in seconds.

Controlled rate freezers remain the method of choice across a range of cell and tissue applications where sample volume makes vitrification impractical, and units performing both require both.

Open and closed carriers under a longer retention window

Open carriers place the sample in direct contact with liquid nitrogen and achieve the highest cooling rate. Closed carriers seal the sample prior to cooling, accepting a modestly slower rate in exchange for eliminating contact.

The consideration is cross contamination. Liquid nitrogen is not sterile and can carry viable organisms between samples held in a shared vessel. Against that, documented transmission in clinical practice is vanishingly rare, and closed systems trade a measurable reduction in cooling rate against a risk that is largely theoretical.

Both positions are defensible on the evidence. A position that has not been decided, documented and justified is not, and it is the one an inspector will identify.

It is worth noting that retention period enters this calculation. The arithmetic of low probability events across a fifty year store differs from that across a ten year store, and a position adopted under the previous regime merits revisiting rather than assuming.

Traceability across decades

Identification must remain legible at cryogenic temperature for the duration of storage, and must survive staff turnover, changes of laboratory information system and any relocation of the store. Consent status must be tracked against a ten year reconsent cycle for every stored sample, an administrative burden the previous regime did not impose.

The case for continuous monitoring

In March 2018 two unrelated fertility clinics in the United States sustained cryogenic storage failures on the same weekend, and thousands of eggs and embryos were lost.

The conclusion drawn across the sector concerned observability rather than equipment selection. Failures of this class develop slowly and produce no signal until they are well advanced, and a store lacking continuous monitoring and alarms depends upon a member of staff happening to pass it.

Four elements separate a maintenance task from an incident: continuous level and temperature monitoring; an alarm path that reaches a named individual outside working hours; oxygen depletion monitoring for the protection of personnel; and a written escalation procedure that has been tested rather than filed.

Full article: https://cryolab.co.uk/embryo-cryopreservation-55-year-storage-limit/

Sizing the risk in your own store

Liquid nitrogen expands approximately 683 to 1 by volume as it warms to room temperature, a figure published in BCGA Code of Practice 30. A 175 litre storage vessel therefore represents in the order of 120 cubic metres of nitrogen gas. A store measuring four metres by five by three is 60 cubic metres.

This is not a prediction of a release event. No vessel discharges its contents at once. It is a way of establishing the margin, which in most units is smaller than staff assume.

The margin also erodes without announcement. A store commissioned around a single vessel acquires a second. Delivery dewars are left in the corner while somebody locates the trolley. Every vessel boils off continuously and every fill vents a surge. A room that was adequately ventilated for one vessel is not automatically adequate for three, and nothing in the room's appearance records the change.

Why oxygen monitoring is not optional

Nitrogen is inert and already constitutes most of the atmosphere. There is no physiological detection of it, and none of falling oxygen. CP30 states that asphyxia due to oxygen deficiency is often rapid with no prior warning to the victim.

HSE recommends that workplace oxygen remains above 19.5 per cent. The University of St Andrews publishes trigger points of 19.5 per cent for urgent investigation and 18 per cent for immediate evacuation, which are defensible values to adopt rather than deriving local ones.

Two points of implementation are worth stating because they are commonly missed. First, the alarm indicator belongs on the outside of the store door, so the warning reaches the person who has not yet entered. Second, vessels should travel in lifts unaccompanied.

Ice plugs in open neck dewars

Storage dewars used for sample banking are not pressure vessels. The closure is a loose insulating plug and the neck vents to atmosphere. Moisture from the room can freeze within the neck, and CP30 sets out the consequence: an ice plug can form a seal that prevents the release of gas, leading to a rise in internal pressure, with a ruptured vessel as the end point.

The controls are procedural rather than capital. Use only the stopper supplied with the vessel and never a tighter substitute intended to reduce boil off. Inspect the neck visually on every access. Train staff that a vessel hissing more than usual, or showing a swollen neck, is grounds for leaving the room rather than raising a maintenance request.

Contact injury

At approximately minus 196°C liquid nitrogen freezes skin on contact, and CP30 warns of severe damage to skin from contact with liquid or cold gaseous nitrogen. Aluminium canes and goblets withdrawn from a vessel are sufficiently cold to adhere to bare skin, and a splash to the eye is the injury with the most serious long term consequence.

Protection is straightforward: loose fitting insulated gloves, chosen loose specifically so they can be removed immediately if liquid enters them, a full face shield rather than safety glasses when decanting, an apron from which liquid runs off, and closed shoes.

What the professional guidance asks of monitoring

ESHRE's 2026 good practice recommendations for the IVF laboratory expect cryostorage tanks to be continuously monitored, with alarms that detect and log out of range temperature or liquid nitrogen level.

ASRM's 2020 cryostorage opinion is more specific on instrumentation and recommends level probes in the liquid rather than temperature probes in the vapour, on the basis that level falls first. For units currently specifying or replacing monitoring, that distinction is the practical one: vapour phase temperature is a lagging indicator, and level is the leading one.

Alarms also require a response plan that names an individual reachable at two in the morning and states where the backup vessel is held. An alarm with no assigned responder is a sound, not a control.

The routine that outperforms instrumentation

The most informative record in a cryo store remains the fill log. Recording date, vessel and litres for every fill, alongside a daily dipped level, will reveal a failing vacuum through rising consumption at unchanged workload, typically weeks before any probe registers a change.

Full article: https://cryolab.co.uk/liquid-nitrogen-tank-safety/

The vessel is the last decision, not the first

A storage vessel is the largest single line, carries the longest lead time and requires the highest level of approval. Every feature of the procurement process therefore pushes it to the front of the queue.

It is also the item that is most constrained by decisions that have not yet been made.

Straw format determines which goblets are compatible. Goblet selection determines canister layout. Canister layout determines the rack configuration and neck required in a vessel. Specify the vessel first and those downstream choices are constrained by a decision that preceded them, usually without anyone noticing that a constraint has been created.

The resulting failure is unremarkable and expensive. A straw format is selected some months later, after goblets and canes have been purchased, and does not fit the organisation system already in place. Nothing is defective and nothing is under warranty. The tank furniture is simply reordered.

A test worth applying to any specification before sign off: every straw format intended for use in the laboratory should have a documented path to a specific canister position. Where that path cannot be written down, the specification is incomplete, however complete the purchase order appears.

Capacity planning has changed regime

Since 1 July 2022, per the HFEA, UK patients may store eggs, sperm and embryos for up to 55 years provided they reconsent every ten years.

The operational consequence deserves more attention than it generally receives. Under the previous ten year limit, storage was substantially self clearing. Outflow approximated inflow and capacity planning was a rolling exercise. Under the current regime, outflow reduces to a trickle and inventory accumulates.

Capacity models carried over from before July 2022 therefore systematically underestimate. Sizing a vessel against current inventory reflects the previous behaviour, which is the most common route to a vessel reaching capacity within two years of installation. The remedy at that point is another vessel, which makes it the most expensive error in this category.

Two questions for every quotation

What is the static evaporation rate of this vessel, and what does that translate to as a weekly nitrogen order?

These are total cost of ownership inputs rather than technical curiosities. Two vessels at comparable purchase prices can differ materially in running cost over a ten year horizon, and the difference sits almost entirely in that figure. Where it does not appear on the specification sheet, it should be requested in writing.

Freezing method is a branch, not a default

For embryos and oocytes, ASRM's 2021 Practice Committee opinion recommends vitrification as standard of care. The equipment implication is that the purchase is a kit, carriers and a bench dewar rather than a machine.

Sperm, and a substantial proportion of tissue and cell banking work, continue to use slow programmable freezing, which requires a controlled rate freezer with chamber capacity matched to batch size rather than to available budget.

Units performing both need both. This warrants stating explicitly in a business case, because to anyone reviewing line items without clinical context it presents as duplication.

Monitoring, and the half of it that gets omitted

ESHRE's 2026 good practice recommendations state that cryostorage tanks should be continuously monitored with alarm systems that detect and log any out of range temperature or LN2 level.

There are two requirements in that sentence. Detection and logging. A number of systems satisfy the first without satisfying the second, and the logging requirement is the one that matters at inspection.

Larger vessels are commonly supplied with level, temperature and power alarms together with a remote alarm output. Smaller vessels generally require monitoring to be added separately, and a manual dipped level remains the simplest daily check, requiring no power and no calibration.

The item most frequently absent from budgets is the relay itself. An alarm sounding in an unoccupied laboratory at two in the morning has communicated nothing. The connection to a building management system or an autodialler, together with a named out of hours responder, is what converts detection into response, and it represents a small fraction of the value of the inventory it protects.

Protective equipment

Liquid nitrogen causes cold burns on contact and displaces oxygen as it boils. BCGA Code of Practice 30 notes that asphyxia due to oxygen deficiency is often rapid with no prior warning, and records the HSE recommendation that workplace oxygen be kept above 19.5 per cent.

This category is routinely reduced at the point where a budget requires trimming, on the reasoning that it is not clinical equipment. It protects the people operating everything else on the list.

Full guide: https://cryolab.co.uk/cryopreservation-equipment-procurement-guide/

The HFEA's extension of maximum storage to 55 years in defined circumstances reflects this evidence base. It is a regulatory acknowledgement of the science, not a clinical compromise.

What warrants more discussion in the professional community is the infrastructure gap: the difference between what the biology can sustain and what the storage systems actually provide. Vacuum insulation integrity in clinical storage vessels degrades progressively and silently. LN2 supply interruptions, particularly during bank holidays and out-of-hours periods, create temperature excursion risk that is not reflected in the biological literature because poorly maintained storage is underreported. Alarm systems that are not integrated with out-of-hours notification protocols provide false assurance.

The HFEA Code of Practice requires documented equipment validation and continuous monitoring. The gap between regulatory requirement and clinical practice in this area deserves more attention than it currently receives.

Cryolab, with over 40 years of experience supplying cryogenic storage equipment to IVF laboratories, has published a detailed guide covering the science, the regulatory framework, the consent dimension, and the infrastructure requirements for long-term embryo storage: https://cryolab.co.uk/how-long-can-embryos-be-stored/

The vacuum-insulated dewar, invented by Sir James Dewar in 1892 and largely unchanged in its fundamental architecture, is the storage vessel that holds every frozen embryo in clinical storage. Its performance is determined by the quality of its vacuum insulation, which degrades over time. The failure mode is silent and progressive: increased LN2 consumption, reduced holding time, and eventually temperature instability. The clinical consequence in an unmonitored or inadequately maintained vessel is sample loss that may not be detected until years after the storage failure occurred.

Modern high-capacity cryogenic storage systems, such as the CryoBank Series from Cryolab (350-1800L, with automated LN2 supply, continuous monitoring, and remote alarm integration), address these failure modes through engineering and monitoring architecture rather than manual oversight. For IVF networks and biobanks operating at scale, the case for high-capacity automated storage over multiple smaller manually managed dewars rests primarily on risk reduction rather than cost.

Cryogenic transport represents a distinct technical challenge. IATA regulations prohibit free liquid nitrogen on commercial aircraft. Vapour phase dry shippers (cryoshippers) provide the clinical solution: an absorbent matrix saturated with LN2 vapour maintains approximately -190°C without free liquid, compliant for air freight. The technical performance parameters -- holding time, charging time, temperature uniformity across the sample cavity -- vary significantly between products and warrant the same scrutiny applied to storage vessel selection.

The complete guide to cryogenic technology, covering the physics, the engineering, the applications, and the UK regulatory framework: https://cryolab.co.uk/cryogenic-technology-complete-guide/

Vitrification technique and outcomes: cooling rates exceeding 15,000 degrees Celsius per minute, elimination of ice crystal formation, post-warming survival rates consistently above 90 percent in experienced laboratories, and the NYU Langone outcome data showing 70 percent live birth rate from 20 or more vitrified oocytes thawed before age 38.

Cryoprotectant protocol: the dehydration step using permeating agents (ethylene glycol, DMSO) and non-permeating agents (sucrose), the critical timing window, and how protocol quality translates directly into post-warming survival.

Storage infrastructure: the clinical significance of the -130 degree Celsius glass transition temperature, the consequences of temperature excursions above this threshold for stored oocytes, HFEA continuous monitoring requirements for licensed UK facilities, and the cross-contamination risk implications of screw-cap versus hermetically sealed container systems.

Outcome data and patient communication: the NYU Langone cohort findings on egg number thresholds, the declining mean age at freezing (36.9 to 35.0 years across an 8-year, 4,659-cycle study), and the unexpectedly low return-to-use rate that raises questions about whether the procedure is reaching the patients who would most benefit from earlier intervention.

Warming protocol requirements: ice recrystallisation prevention during the -130 to 0 degree Celsius transition, stepwise cryoprotectant dilution, and the consequences of protocol deviation at this stage.

The guide is aimed at a mixed readership of practitioners and informed patients and may serve as a useful reference for patient education discussions