Common Exceptions in Diagnostic Kitting
Key takeaways
The most common diagnostic kitting exceptions are component shortages, expiry date mismatches, labeling errors, damaged or incomplete kits, temperature deviations and recalls of components.
Every exception should follow the same path: contain the affected kits, assess the risk, decide disposition, fix the root cause and record what was done.
FDA's Quality Management System Regulation, effective February 2, 2026, requires device manufacturers to inspect labeling and packaging for accuracy, including the device identifier, expiration date and storage instructions, and to prevent mixups.
Under 21 CFR 809.10, in vitro diagnostic labels carry a lot or control number and, for reagents, an expiration date, and units used together as a system should share a lot number or other uniform identification where appropriate.
CAPA turns a kitting exception into a lasting fix by finding the root cause, correcting the process and checking that the same error does not return.
Diagnostic kitting exceptions are the moments when a kit cannot be built, released or used exactly as specified. A tube runs out, a component expires before the kit does, a label prints with the wrong lot, a box arrives crushed at a collection site or a refrigerated reagent sits too long on a dock. Each one can delay patient testing or force a redraw, and each one carries a quality question: is this kit still fit for use, and why did the problem happen?
This guide covers the exceptions that come up most often after a kit has been designed, how to handle each one and how corrective and preventive action (CAPA) keeps the same kitting errors from coming back. Designing the kit itself, including layout, instructions and packaging tests, is covered in our guide to user-centric design in diagnostic kitting.
What are common exceptions in diagnostic kitting?
The common exceptions in diagnostic kitting are component shortages, expiry date mismatches between components, labeling errors, damaged or incomplete kits, temperature deviations during storage or shipping and recalls or quality holds on a component. Most diagnostic kit quality issues fall into one of these groups, and each has a typical cause and a first response.
Exception | Typical causes | First response | Who usually decides disposition |
|---|---|---|---|
Component shortage | Supplier delay, forecast miss, single-source part, unplanned demand | Stop new builds that need the item, check safety stock and approved alternates | Quality and supply chain, with regulatory input if a substitute is proposed |
Expiry date mismatch | Mixed component lots, short-dated stock picked first, kit expiry not tied to the earliest component | Quarantine affected kits and recalculate the kit expiry | Quality |
Labeling error | Wrong template, wrong lot or expiry data, printer fault, label mixup between products | Quarantine all kits from the affected run, reconcile labels issued against labels used | Quality, with regulatory input if released kits are affected |
Damaged or incomplete kit | Pick or pack error, missing count check, weak packaging, handling damage in transit | Replace the kit for the user, quarantine the returned kit, check the same build lot | Quality and customer service |
Temperature deviation | Storage unit failure, dock dwell, packaging not qualified for the season or lane | Quarantine, download logger data, compare with stability data | Quality, with the component manufacturer if needed |
Component recall or quality hold | Supplier notice, internal test failure, complaint trend | Identify every kit that contains the affected lot and stop distribution | Quality and regulatory |
The table shows a pattern. Almost every exception starts with containment, because a kit that should not be used is far easier to stop in the warehouse than in a clinic. The rest of this guide takes the main exceptions in turn.
How do you handle component shortages in kitting?
You handle component shortages in kitting by protecting the kits already built, deciding whether an approved alternative exists and changing build priorities based on which sites and studies need kits first. A shortage should never be solved by quietly substituting a different part.
A practical sequence for kit component shortages has five steps.
Confirm the gap. Check on-hand stock, open purchase orders, confirmed supplier dates and how many kits the remaining stock can complete.
Protect critical demand. Rank kit orders by clinical urgency, study timelines and site inventory, and allocate the remaining components to the most critical orders.
Check for an approved alternate. Only use a substitute that is already approved in the kit specification. A new supplier or a different collection device may change the kit's validated performance or its labeling and needs a documented change review first.
Tell sites early. Give sites realistic dates and, where possible, ask them to report on-hand kits so stock can be moved between locations.
Record the event. Log the shortage, the decisions made and their impact so that the root cause can be addressed through CAPA.
Over the longer term, shortages are reduced by second sources for critical components, safety stock sized to supplier lead times and demand forecasts updated with real site usage. Our article on just-in-time inventory management for diagnostics explains how to balance stock levels against expiry risk.
Handling expiry date mismatches
Expiry date mismatch kits are kits in which one component expires earlier than the date on the kit label, or in which components from different lots carry different dates. The kit cannot safely outlast its shortest-dated component, so the kit expiry should be set by the earliest-expiring component that affects its use.
The US labeling rule for in vitro diagnostic products supports this approach. Under 21 CFR 809.10, reagent labels must include a means of assuring the product meets its standards at the time of use, such as an expiration date based on the stated storage instructions, and labels must carry a lot or control number from which the complete manufacturing history can be determined. For multiple-unit products that are used together as a system, the rule says all units should bear the same lot or control number where appropriate, or other suitable uniform identification should be used.
To prevent expiry mismatches, build kits from components picked by earliest expiry, calculate the kit expiry automatically from the component lots used and block release of any kit whose label date is later than its shortest-dated component. When a mismatch is found, quarantine all kits from the affected build, relabel or rework only under an approved procedure and check whether kits already shipped need to be replaced.
How are labeling errors in diagnostic kits prevented?
Labeling errors in diagnostic kits are prevented by controlling label content at the source, inspecting labels before and during use, reconciling labels issued against labels used and separating label runs so that labels for one product or lot cannot end up on another. Kit labeling errors are among the most serious kitting errors because a wrong lot or expiry date can hide a problem or trigger an unnecessary recall.
FDA's Quality Management System Regulation (QMSR) took effect on February 2, 2026 and incorporates ISO 13485:2016 by reference. Its labeling and packaging section, 21 CFR 820.45, requires manufacturers to examine labeling and packaging for accuracy before release or storage where applicable, including the unique device identifier or other device identification, the expiration date, storage instructions, handling instructions and any additional processing instructions. It also requires labeling and packaging operations that prevent mixups, including inspection before use, with the results documented.
The QMSR applies to manufacturers of finished devices, and its definition of manufacturer includes firms that relabel or repack devices. Whether your kitting operation falls under it depends on what you assemble and how it is marketed, so confirm the status of each kit with your regulatory team.
Kitting quality control for labels usually rests on five measures.
Locked templates. Approved label templates that operators cannot edit, with lot and expiry data pulled from the inventory system rather than typed.
Line clearance. Removing all labels and components from the previous run before a new run starts.
Scan verification. Scanning the kit label against the build record and component lots before the kit is sealed.
Label reconciliation. Counting labels issued, used, damaged and returned at the end of each run, and investigating any difference.
First-article and in-process checks. A documented second-person check of the first kit in each run and periodic checks during the run.
What should happen when a kit arrives damaged or incomplete?
When a kit arrives damaged or incomplete, the site should not use it, the user should receive a replacement quickly and the kit or a clear record of it should go back to the kitting team for investigation. The goal is to protect the patient or sample first and then find out whether the problem affects other kits from the same build or shipment.
A clear response for incomplete diagnostic kits and damaged kits includes these steps:
Document at receipt. Ask the site to photograph the outer box, inner packaging and contents and to note what is missing or damaged.
Replace fast. Ship a replacement kit on a service level that meets the collection date. For urgent cases, a same-day courier can close the gap.
Return or quarantine. Bring the kit back for inspection, or have the site quarantine and dispose of it under instructions if a return is not practical.
Check the build lot. Review the build record, pack counts and any scan data for the same lot, and inspect retained kits if available.
Separate packing from transit causes. A missing component points to the build process. A crushed box or broken tube may point to packaging or handling in transit.
Log it as a complaint. Under 21 CFR 820.35, device manufacturers must keep records of the review, evaluation and investigation of complaints involving a possible failure of a device, its labeling or packaging to meet specifications.
Damage in transit is often a packaging qualification question. Collection kits that travel to sites and return as specimens also need the right return packaging and pickup plan. Our guide on streamlining pickup processes for diagnostic kits covers the return leg.
Temperature deviations and component recalls
Temperature deviations need a defined decision path. Quarantine the affected kits, download the logger data, compare the time and temperature profile with the stability data for each temperature-sensitive component and let quality decide whether the kits can be released, need further testing or must be destroyed. Our guide to protecting diagnostics kits from temperature excursions covers prevention and response in detail.
Component recalls require traceability. If a supplier recalls a lot of collection tubes or reagent, you must be able to find every kit that contains it, where those kits were shipped and how many remain unused. Under 21 CFR 806.10, device manufacturers and importers must report to FDA, within 10 working days of initiation, any correction or removal undertaken to reduce a risk to health posed by the device or to remedy a violation that may present a risk to health, unless an exemption applies. Kit owners should agree in advance with suppliers and regulatory staff who decides whether a component recall triggers a kit correction or removal. Our article on medical device recall logistics explains how to retrieve product from the field.
How does CAPA apply to kitting exceptions?
CAPA applies to kitting exceptions by turning each significant or repeated problem into a documented investigation that finds the root cause, fixes the process and checks that the fix works. Correcting the single kit is a correction. Changing the process so that the same kit error cannot recur is corrective action, and addressing a similar risk before it happens elsewhere is preventive action.
Because the QMSR incorporates ISO 13485:2016, device manufacturers subject to 21 CFR 820 follow that standard's requirements for corrective and preventive action alongside FDA's own supplemental provisions, such as the complaint record requirements in 820.35. CAPA kitting work usually follows these stages:
Trigger. Define what opens a CAPA, for example any labeling error on released kits, any repeat of the same exception within a set period or any temperature deviation that led to destruction of kits.
Containment and correction. Quarantine, rework or replace the affected kits and record what was done.
Root cause investigation. Use tools such as a 5-whys analysis or a cause and effect diagram, and check build records, training, equipment, materials and supplier data.
Action plan. Change the process, for example by adding a scan step, changing a label template control, qualifying new packaging or adding a second source.
Verification of effectiveness. Agree in advance how success will be measured, such as zero repeats over a defined number of builds, and check it.
Closure and trending. Close the CAPA with evidence, and review exception data regularly to spot trends before they become CAPAs.
Logistics exceptions belong in the same system. A late pickup, a missed delivery or a damaged shipment is an exception with a root cause that can be fixed. Our article on exception management in logistics explains how to track shipping problems so they feed into quality reviews.
Building an exception-ready kitting operation
Exceptions cannot be removed entirely, but they can be made rare, visible and quick to resolve. The operations that handle them best share a few traits: written procedures for each exception type, clear ownership of disposition decisions, traceability from component lot to shipped kit and a CAPA process that changes the way kits are built rather than only fixing the kit in hand.
Shipping is part of that picture. Mercury supports diagnostic kit shipping with same-day courier, next flight out, temperature-controlled options and real-time tracking, so that kit owners can replace a failed kit quickly and see where shipments are when a deviation needs to be investigated.
