Why IVF Manufacturers Rely on Sperm Assays?
A finished IVF disposable or culture medium can meet dimensional, chemical, sterility, and release specifications yet still raise a biological-compatibility question: does the article, its extractables, or the way it was processed adversely affect sperm motility or survival under the conditions tested? For manufacturers, that question can arise at almost every point in the product lifecycle, from supplier qualification and formulation development to shelf-life studies, complaints, and corrective and preventive action (CAPA).
The Human Sperm Survival Assay (HSSA) can add a human-cell response to that evidence package. It is best positioned as a complementary, fit-for-purpose bioassay, not as a clinical diagnostic, proof of clinical outcomes, a universal regulatory requirement, or an automatic replacement for the Mouse Embryo Assay (MEA).
MANUFACTURER TAKEAWAY
Use HSSA to answer a defined product or quality question. Predefine the test article, extraction or exposure conditions, endpoint, control, acceptance criterion, and decision pathway. Interpret the result with the rest of the evidence - not in isolation.
What HSSA measures and what it does not
HSSA is a family of laboratory bioassays in which human sperm are exposed to a test material, an extract, or a medium under specified conditions. Motility and/or survival is then compared with an appropriate control over a defined incubation period. The output is a sperm-related biological response to the tested conditions. Depending on the protocol, results may be expressed as a test-to-control ratio or another predefined index.
Protocol details matter. Test-article preparation, surface-area-to-volume ratio, extraction vehicle, temperature, contact time, sperm-sample acceptance criteria, analytical method, endpoint timing, controls, and cutoff can all affect the result. A claim of “HSSA tested” is therefore incomplete unless the method and intended use are clear.
The 2003 multicenter consensus-protocol study supports interlaboratory reproducibility under the conditions evaluated, but it also stated that assay sensitivity remained to be established. Sensitivity can vary by toxicant and protocol. The published evidence does not establish HSSA as equivalent to MEA, does not show that an HSSA result predicts pregnancy or live-birth outcomes, and does not make the assay a substitute for a manufacturer’s broader biological-safety, chemical-characterization, sterility, or regulatory strategy. [1]
Where HSSA can strengthen a manufacturer’s quality evidence
The strongest use cases begin with a specific uncertainty. HSSA may help determine whether a change or suspect condition produces a sperm-related effect that routine physical, chemical, or microbiological tests do not directly measure.
1. Raw-material and supplier qualification
For polymers, resins, additives, coatings, lubricants, adhesives, media ingredients, proteins, oils, and primary packaging, supplier documentation is necessary but may not resolve biological-response risk. A risk-based HSSA study can support qualification when a material has direct or indirect contact with sperm, when composition or impurity profiles vary, or when a new source is introduced.
The assay should not become a blanket incoming test without a rationale. Its value is greater when tied to material criticality, supplier history, chemical characterization, change-notification controls, and the manufacturer’s knowledge of the contact pathway.
2. Formulation and material compatibility during development
During media formulation or disposable development, HSSA can help compare candidates, concentrations, contact materials, colorants, printing systems, bonding agents, or surface treatments. For culture media, direct exposure may be appropriate; for devices, a justified extraction or simulated-use design may be more relevant. Matrix effects, osmolality, pH, viscosity, and other product attributes must be controlled so that the assay distinguishes formulation performance from unintended test interference.
A comparative design can be especially informative: current versus proposed formulation, incumbent versus alternate material, or pre-process versus post-process article. The conclusion should remain bounded to the endpoints and conditions studied.
3. Design verification and process-change assessment
HSSA can contribute to design verification when sperm contact is part of intended use and the test is linked to a predefined design input or risk control. It can also support change assessment for molding parameters, cleaning agents, curing, bonding, printing, coating, filling, or hold times.
Packaging and sterilization deserve explicit attention. Changes in pouch, tray, label, ink, adhesive, sterilization modality, dose, residual management, aeration, or shipping configuration may alter the chemical environment of the finished product. Testing the final, packaged, and processed article - or a justified worst case - can be more decision-relevant than testing a component before those steps.
4. Lot-to-lot consistency and release strategy
A qualified HSSA method may be used to monitor consistency across pilot, validation, or commercial lots when the endpoint is relevant to the product risk. The sampling plan should reflect within-lot and between-lot variability, and acceptance criteria should be established before results are reviewed.
Not every product needs HSSA at release. A manufacturer might instead use it for process validation, periodic monitoring, first lots after a change, or elevated-risk materials. The frequency should follow the control strategy, process capability, supplier performance, complaint history, and severity of the biological risk.
5. Stability and shelf-life investigations
A biological response can change as a product ages, especially when storage, packaging interactions, degradation, evaporation, gas exchange, or sterilization residuals are plausible contributors. HSSA can be incorporated into real-time or accelerated stability investigations at justified intervals, alongside the product’s chemical, physical, microbiological, and functional measures. Accelerated results should not be overinterpreted if the aging mechanism is not representative of real-time storage.
6. Complaint, deviation, and CAPA support
When a complaint or deviation suggests possible product-related toxicity, HSSA can be one line of evidence in a structured root-cause investigation. Useful comparisons may include retained versus complaint sample, affected versus unaffected lot, suspect versus approved raw material, or pre-change versus post-change process.
The method can help narrow hypotheses, but it does not identify a chemical cause by itself. Pairing the biological signal with manufacturing records, supplier data, nonconformance trends, analytical chemistry, sterility information, and packaging or sterilization records is what turns a result into an actionable investigation. CAPA effectiveness criteria should be defined independently of the desire to obtain a passing retest.
What the published studies add to the risk conversation
The HSSA literature spans multiple protocols and intended uses. A 2003 paper described a multicenter consensus protocol and demonstrated interlaboratory consistency under the evaluated conditions, while leaving sensitivity unresolved. [1] A later Ramsay Santé program registered as REPROTOX 2 evaluated IVF consumables using a related human sperm motility assay (HSMA). [2]
In the 2024 HSMA publication, the study-specific Sperm Motility Index was the ratio of progressive motility in the test condition to the control after 24 hours, with a 0.85 cutoff. The investigators tested 53 lots across 36 consumable types and also assessed 48 groupings of three to five devices under deliberately stringent extraction conditions. Individually, 49 of 53 lots passed; 17 of 48 combinations showed toxicity even though their individual devices had passed. Failure frequency increased with the number of devices in the tested grouping. The authors cautioned that the extraction conditions may not reflect routine clinical use, and the study did not compare HSMA head-to-head with MEA or measure clinical outcomes. [3]
A 2026 follow-up used MEA to evaluate ten device combinations. It did not find an inherent cumulative effect; the two toxic combinations were traced to two specific device references, sperm straws and embryo transfer catheters, rather than to combination use itself. The authors called for further work on cumulative toxicity in routine practice. [4]
For manufacturers, these findings do not justify a universal combination-testing rule. They do reinforce two practical principles: certification of individual inputs does not remove the need to assess the final article and relevant changes, and an unexpected biological signal requires source isolation rather than a broad conclusion about an entire workflow.
HSSA and MEA answer related, not interchangeable, questions
MEA evaluates embryo-development endpoints, while HSSA evaluates sperm-related endpoints. Those endpoints can respond differently to a substance, concentration, exposure condition, and protocol. A “pass” in one assay should not be presumed to predict a pass in the other unless equivalence has been established for the defined product, method, and decision.
FDA guidance recommends MEA for many assisted-reproduction-technology devices, and certain device classifications include MEA-related special controls. The guidance is nonbinding, excludes some sperm-only devices, and does not create a universal requirement for every IVF product. HSSA is not identified there as a generally accepted MEA substitute. Manufacturers should map the applicable classification, claims, market, standards, and regulator expectations before selecting a testing strategy. [5]
Build a fit-for-purpose Sperm Testing Program
A defensible program connects assay design to the decision it must support. Before testing begins, document the following:
● Intended use: screening, comparative development, verification, change assessment, monitoring, stability, or investigation.
● Test article and worst case: component, finished device, packaged and sterilized product, formulation, aged sample, or process challenge.
● Exposure model: direct contact, extraction, simulated use, vehicle, ratio, time, temperature, agitation, and recovery conditions.
● Endpoint and timing: progressive motility, total motility, survival, or a defined composite; the calculation and observation window.
● Controls and system suitability: negative and positive controls, sperm-sample eligibility, replicate structure, and rules for invalid runs.
● Performance characteristics: precision, intermediate precision, robustness, specificity or interference, range, detection capability where relevant, and reproducibility appropriate to the intended use.
● Acceptance criteria and statistics: prospectively justified thresholds, handling of borderline results, sample size, variability, and multiple comparisons where applicable.
● Decision pathway: confirmatory testing, source isolation, escalation, release hold, supplier action, deviation, or CAPA - and how HSSA integrates with other evidence.
This discipline prevents a biological assay from becoming a simple pass/fail label. It also creates a traceable connection among risk management, method qualification, design and process controls, and the final quality decision.
Make the assay answer your manufacturing question
For IVF disposable and culture-media manufacturers, the value of HSSA is not that it replaces another test. Its value is that it can provide a defined human-sperm endpoint when a material, formulation, finished product, process, aged sample, or suspect lot presents a question that other controls do not fully answer.
Spermatica Laboratories works with manufacturer quality, R&D, regulatory, and operations teams to scope fit-for-purpose HSSA studies, define interpretable controls and acceptance criteria, and design comparisons for development, verification, change assessment, stability, and investigations.
NEXT STEP
Bring us the decision - not just the sample. Start a manufacturer study-design discussion to map the product risk, test conditions, comparator, and evidence needed for the next quality decision.
References
1. de Jonge CJ, Centola GM, Reed ML, et al. “Human Sperm Survival Assay as a Bioassay for the Assisted Reproductive Technologies Laboratory.” Journal of Andrology. 2003;24(1):16–18. https://onlinelibrary.wiley.com/doi/full/10.1002/j.1939-4640.2003.tb02629.x
2. GCS Ramsay Santé pour l’Enseignement et la Recherche. “The Human Sperm Survival Assay (HSSA) as an Internal Quality Control for the IVF Consumables (REPROTOX 2).” NCT05100784. https://clinicaltrials.gov/study/NCT05100784
3. Delaroche L, Besnard L, Ouary V, Bazin F, Cassuto G. “Disposables used cumulatively in routine IVF procedures could display toxicity.” Human Reproduction. 2024;39(5):936–954. https://pmc.ncbi.nlm.nih.gov/articles/PMC11063546/
4. Delaroche L, Besnard L, Bazin F, et al. “The sequential use of IVF disposable devices doesn’t cause cumulative toxicity unless a defective device compromises the entire procedure.” Scientific Reports. 2026. https://pmc.ncbi.nlm.nih.gov/articles/PMC12886905/
5. U.S. Food and Drug Administration. “Mouse Embryo Assay for Assisted Reproduction Technology Devices—Guidance for Industry and Food and Drug Administration Staff.” January 5, 2021. https://www.fda.gov/media/127874/download
Important limitation. This article describes possible quality-system uses of HSSA. It is not regulatory or clinical advice. Assay design, validation or qualification, and acceptance criteria must be appropriate to the product, intended use, jurisdiction, and decision being supported.