Immediately after receiving a sputum we will perform a gram stain on it to perform a screen. Those pink flakes you see there are squamous epithelial cells which are found at the mouth. To prevent a whole bunch of contaminant bacteria from obscuring our dishes we look for the following: < 25 epithelial cells per low power field (LPF) OR > 25/LPF neutrophils If this is not met, the sample is rejected. It’s a luck thing. It’s not that anyone is doing something wrong, just depends on how nice and ripe your phlegm is.   submitted by   /u/Muted_Shape9303 [link]   [comments]