The two primary methods of moving specimens through the laboratory process are:
- Batch or manual transport, often with the use of racks of multiple specimens (batch transfer)
- Continuous feed of single specimens in an uninterrupted flow from one process step to the next
Batch processing is an older process design that continues to be commonplace in traditional, non-automated histology laboratories. Batch and queue processing cause longer lead times, and greater wait times and bottlenecks between process steps. Another effect that can be exaggerated in large batching can be batch-to-batch irregularities due to inconsistencies in individual performances especially when there is also a lack of standardization. Some batch-to-batch inconsistencies can be reduced by tight standardization of procedures, but even with good standardization, the consistency achieved is less than achievable by continuous flow automation.
Continuous specimen flow in contrast, seeks to eliminate the delays or wait time between steps seen in batch processing by moving single specimens or much smaller batches uninterrupted through the process. The concept of continuous flow process design was popularized by Taiichi Ohno, who promoted the idea of the continuous flow as the most efficient way to move items through any process. It is not just as simple as doing one thing at a time, so in order to see the benefits of continuous flow, you must commit to process editing, and reworking of the physical space and equipment used in the process. An ideal physical layout includes work space which has been arranged in a straight formation or modified U-Shape. It is sometimes easiest to begin with organizing and editing the physical space first, and then carefully design the process and select instruments which will enhance the desired continuous flow. The overall goal is to not create excess groups of product or work in progress (WIP) which sit and wait to enter the next process step.
Other benefits of single flow or small batch flow may be to reduce stress on staff since they are never confronted with large unmanageable batches of specimens at any given time. Instead, each specimen is handled individually or in much smaller groups of specimens, which are now more evenly spread out over time. This reduces overall stress and fatigue which can result from long periods of handling large, unmanageable volumes. Reduction of this ambient stress will diffuse staff burnout and often contribute to the reduction of human intervention errors.