Reporting Microscopic Findings

Gram-stained direct smears are examined using the oil immersion objective of the microscope (total magnification =1000x). Before examining the smear by oil immersion, the slide should be scanned on low power field (100x) and high power field (400x) to look for suitable fields, areas of best staining, and large objects such as hyphae and clusters of yeast.

Low power examination is best for scanning for signs of inflammation (white blood cells, purulence - versus areas of contamination with squamous epithelial cells). Continue to examine under low power for a properly stained smear.

The quantity and type of bacteria and nonbacterial cellular elements present are recorded. A minimum of 10 microscopic fields should be scanned before examining the slide under oil, and then reporting the Gram stain result. (To clarify, Leber et al. recommend scanning a minimum of 10-20 low-power fields, then examining at least 20 oil immersion fields.)^{2(Gram stain procedure)}

Organisms and other cells that are observed on a Gram-stained smear should be reported with as much description as possible.

Morphology
In addition to the staining reaction, the shape (morphology) of the organisms should be reported (eg, cocci or bacilli). It may also be useful to report the cellular arrangement of microorganisms on the smear; always follow your laboratory's procedure for reporting cellular arrangements.

Cellular arrangements may be described as:

Cells should be enumerated under the low power field (LPF):

1+ (rare), <1/LPF

2+ (few), 1-9/LPF

3+ (moderate), 10-25/LPF

4+ (heavy), >25/LPF

Bacteria should be enumerated under oil immersion field (OIF), also - counted from areas associated with cells:

1+ (rare), <1/OIF

2+ (few), 1-5/OIF

3+ (moderate), 6-30/OIF

4+ (heavy), >30/OIF