Nugent Score Calculator
Calculate the Nugent score from Gram-stain semi-quantitative morphotype results.
More Lactobacillus morphotypes produce a lower score.
More Gardnerella/Bacteroides morphotypes increase the score.
This component contributes a maximum of 2 points.
Select the Gram-stain findings, then calculate the score.
The score breakdown will appear here.
The Nugent score is a standardized microscope scoring system used to help diagnose bacterial vaginosis (BV) from a Gram-stained vaginal smear. Instead of relying only on symptoms, it grades the balance of vaginal bacteria by looking at three bacterial “morphotypes” (shapes/Gram reactions) under oil immersion and assigning points based on how many are seen per high-power field.
What it measures (the three morphotypes)
On the stained smear, the microscopist semi-quantifies:
- Lactobacillus morphotypes (large Gram-positive rods): typically dominate in a healthy, lactobacillus-predominant microbiota. Fewer lactobacilli increases the score.
- Gardnerella/Bacteroides morphotypes (small Gram-variable/negative rods): BV-associated flora; more of these increases the score.
- Curved Gram-variable rods (Mobiluncus morphotypes): when present in higher quantities, they add additional points.
Each component is converted to points (0–4 for the first two, 0–2 for curved rods), then added to produce a total score from 0 to 10.
How to interpret the total score
A commonly used interpretation is:
- 0–3: Lactobacillus-predominant (BV unlikely)
- 4–6: Intermediate microbiota
- 7–10: Consistent with BV
