Immunohistochemistry has become part of routine diagnosis, but in many laboratories the IHC workflow still runs on paper request slips, whiteboards and memory. This guide is for lab managers, histotechnologists and pathologists who want to manage the immunohistochemistry workflow so that stains are ordered correctly, run reliably and reported on time.
Why the immunohistochemistry workflow needs active management
IHC sits at the crossroads of several teams. A pathologist orders stains, often in panels. Histology cuts additional sections. The IHC bench runs the stains alongside controls. Results come back to the pathologist, who interprets them and may order more. Each handoff can lose time or introduce errors.
The consequences are real: delayed diagnoses, repeat sectioning that exhausts small biopsies, and biomarker results that cannot be trusted because a control failed or a pre-analytic condition was not met. Unlike many lab steps, IHC errors are not always obvious on the slide.
Ordering: getting the request right
Structured orders
Free-text requests on paper are a common source of confusion. Electronic orders that link the stain request to a specific case, block and pathologist reduce misreads and lost requests. Ordering panels, rather than single stains one at a time, can reduce rounds of back-and-forth when the differential diagnosis is clear.
Protecting small specimens
For needle biopsies and small samples, every section matters. Some laboratories cut unstained spare sections up front for cases likely to need IHC. That saves time but consumes material and storage, so it is a trade-off to agree on with pathologists rather than a default.
Recording pre-analytic information
For predictive biomarkers, pre-analytic factors such as fixation time and cold ischemia time can influence results, and professional guidelines for certain biomarkers specify how these should be controlled and documented. Capture this information at accessioning and grossing so it is available when results are interpreted.
Running stains: the bench in detail
The IHC bench combines automation with careful manual steps. Points that deserve attention:
- Positive and negative controls. Every run needs appropriate controls, and many laboratories use on-slide controls so that the control tissue experiences the same conditions as the patient tissue.
- Antibody and reagent tracking. Record clone, lot number, dilution and expiry date, and link them to each run. When a problem appears, you need to know which slides used which reagents.
- Protocol control. Staining protocols on automated platforms should be locked and changed only through documented validation.
- Batching versus speed. Larger batches use instruments efficiently but make urgent cases wait. Define how urgent requests are handled.
- Slide labeling. Labels must survive staining and identify case, block and antibody unambiguously.
Reliable labeling ties into broader specimen tracking with barcodes. Scanning block and slide barcodes at sectioning, loading and delivery creates a chain of custody that makes mix-ups far less likely.
Instrument maintenance belongs on the same list. Automated stainers need scheduled cleaning, reagent priming and service, and a logged maintenance history makes it much easier to rule the instrument in or out when staining quality drifts.
Validation and quality assurance
New antibodies, clones, platforms and protocols must be validated before clinical use, and revalidation is needed when significant changes are made. The College of American Pathologists has published guidance on the analytic validation of immunohistochemical assays that many laboratories use as a reference.
Quality assurance continues after validation:
- Review controls on every run and document acceptance or rejection.
- Participate in external quality assessment or proficiency testing for the markers you offer.
- Monitor repeat rates and investigate patterns by antibody, instrument or operator.
- Track discordance between IHC results and other findings, such as molecular testing.
- Keep records retrievable so any result can be traced back to its run, reagents and controls.
For accredited laboratories, these practices are part of what assessors expect to see. The day-to-day implications are discussed in ISO 15189 for pathology laboratories.
Visibility: knowing where every stain is
Most IHC frustration comes from not knowing status. The pathologist does not know whether stains are cut, running or ready. The bench does not know which requests are urgent. A shared worklist that shows each request, its priority and its current step solves much of this.
Useful status points include ordered, sectioned, staining, ready for review and reported. When each step is recorded with a timestamp, you can see where delays accumulate instead of arguing about them.
Measures worth tracking
- Time from IHC order to stained slide delivery.
- Proportion of requests completed within your internal target.
- Repeat stain rate and reasons.
- Number of order rounds per case for common diagnostic questions.
- Control failure rate by antibody.
These fit naturally into the key performance indicators every pathology lab should track. Choose a small set and review them regularly, rather than collecting everything and acting on nothing.
Reporting IHC results
The final report should list the stains performed and their results in a clear, consistent format, with interpretation in context. For predictive biomarkers, follow the reporting elements recommended by the relevant guideline, including the scoring method used.
When results arrive after the main report has been issued, use an addendum and make sure the clinician knows it exists. Pending stains should be listed on any preliminary report so readers do not assume the work is complete.
Common mistakes
- Accepting verbal or hallway stain requests without recording them.
- Running new clones clinically before validation is documented.
- Losing the link between reagent lots and patient slides.
- Treating every request as routine, so genuinely urgent cases wait in the batch.
- Reporting biomarker results without noting relevant pre-analytic limitations.
Most of these mistakes share a root cause: information that lives in someone's head or on a scrap of paper instead of in the record. Each one becomes much rarer once orders, runs and results are linked to the case.
Key takeaways
- Electronic, case-linked orders reduce errors and repeated rounds of stains.
- Controls, reagent traceability and locked protocols are the backbone of reliable IHC.
- Validate before clinical use and continue quality assurance through controls and external assessment.
- A shared worklist with timestamps turns IHC delays from a mystery into something you can fix.
- Report clearly, list pending stains, and communicate addenda.
Managing IHC well is mostly about visibility and traceability. PATHOLOGY+ connects case registration, histology workstations, slide printing and the pathologist workspace in one system; book a demo to see how that could support your IHC bench.