Some workflows within histology are simply more complicated and can be more challenging to fully automate and optimize. Immunohistochemistry (IHC) staining is a good example of a more complex workflow that contributes additional challenges to achieving a continuous flow automation design. There have been many automated staining instruments on the market which stain slides typically by the use of a robotic pipetting system which applies reagents to slides in a very controlled manner. Automated instruments alone have greatly improved both turnaround time and stain consistency over manual IHC staining methods. However, until recently, most of these automated stainers have been oriented to batch staining of IHC slides in "runs" where the largest possible groups of slides are stained simultaneously. Therefore, IHC automated instrument throughput has been limited by the slide capacity, the incubation times of individual reagents on a given run, and the time needed for movement of the robotic arms during staining.
As we have noted, in general, batch processing introduces several problems with bottlenecks, wait times, and batch-to-batch variability. This principle also applies to batch-oriented IHC staining instrumentation. Recently, more instruments are being developed with more of a continuous flow, and have been sought out by laboratories seeking to apply Lean methodology and continuous specimen flow process design to their IHC staining workflow.
In a notable example, the Cleveland Clinic Foundation (CCF) recently analyzed the impact of implementing single piece flow processing in their automated IHC staining, in place of their previous batch-oriented process. They began using a single piece flow staining platform with carefully considered workflow changes, and found that it removed both delays caused by slide sorting steps and also wait times associated with waiting for the longest staining protocol to complete before finishing a batched slide run. By changing most of their IHC workload from batch processing to a continuous flow model, CCF was able to maintain their slide staining capacity with two fewer instruments and also allow IHC staining to begin earlier in the day, improving turnaround times. The CCF experience helps demonstrate that even when looking at highly complex workflow, marked improvements are possible when automation and Lean or continuous flow models are effectively employed.