The procedure your laboratory utilizes for bone marrow stains is determined by the type of stainer available to you. The stainer available may also dictate the type of smear preparations that your laboratory makes.
There are several types of automated hematology stainers on the market today. Some stainers are simple continuous-feed stainers with limited programmability. Some are batch stainers that can have multiple programs, customizable to the sample type or stain preference of the user. Other stainers are dip stainers that automatically move a slide rack from bucket to bucket or an inline corkscrew that moves slides down a plate and dispenses stain/solutions at fixed positions. Finally, there are centrifuge stainers that apply stains to a spinning slide tray during programmed intervals.
Hema-tek® stainers, with a fixed stain area, require shorter preparations on long slides, so slide pull preps or differential smears would be the laboratory standard. Since the stain time and volume is fixed, bone marrow slides may need to be stained twice and sometimes even three times for extremely cellular bone marrows. When using this type of stainer, always check the stain quality before coverslipping.
Automated dipping stainers can be used with either long slides or coverslips when utilizing a coverslip basket, so the choice of smear type is driven by laboratory and pathologist preference. As with manual staining times, the laboratory should have a separate program for bone marrow staining that reflects the need for longer contact times.
Wescor® hematology stainers are quite flexible. They are centrifugal stainers that are pre-programmed for rapid, Wright-Giemsa, and May-Grunwald stains, as well as having programmable custom settings. Each stain type can be adjusted for color balance and intensity. They can be used with slides or coverslips when coverslip adapters are utilized. Since it is a centrifugal staining system, stain precipitate is minimized and it is very easy to change programs as you shift from peripheral blood to fluids cytospins to bone marrow.
