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Good Positive and Negative Likelihood Ratios

Good Positive Likelihood Ratio

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Bacterial Vaginosis: Likelihood Ratios

Introduction: None written.

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Tags: Gynecologic Infection Tag this Diagnosis.

The likelihood ratios of findings for Bacterial Vaginosis are listed below. See the left navigation bar to change the display.

Pre-Test Probability (Prevalence): %.	Post-Test Probability (Predictive Value): %.	Switch to display mode.
Note that calculating probabilities from more than one** finding is inherently inaccurate because findings are not independent. (For example, using two positive findings that share a common pathogenesis is likely to overestimate the true probability.)

Good Positive Likelihood Ratio
Finding	Result	+LR	-LR
[ + ] Clue Cells	+ 0 -	3.4	0.6
on vaginal wet mount: >20% Another study evaluating for "clue cells present" gave sens=96%, spec=99% Study: Infect Dis Obstet Gynecol. 2001;9(2):105-11. PMID: 11495550 alt: J Clin Microbiol. 2005 Mar;43(3):1304-8. PMID: 15750100

Poorly Diagnostic Findings
Finding	Result	+LR	-LR
[ + ] Whiff Test	+ 0 -	0.5	1.1
Adding 10% KOH to the vaginal discharge yields a fishy odor (NOT diagnostic!!) Study: Infect Dis Obstet Gynecol. 2001;9(2):105-11. PMID: 11495550

Findings With Unspecified Accuracy
Finding	Result	+LR	-LR
[ + ] Nugent Criteria		No accuracy specified.
on Gram stain, Gardnerella and/or Mobiluncus predominate with few or no Lactobacilli The Nugent method is a standardized point scoring system (scores from 0 to 10) based on the presence of three bacterial morphotypes: large gram-positive rods (Lactobacillus spp.), small gram-negative or gram-variable coccobacilli (Gardnerella and anaerobic spp.), and curved gram-variable rods (Mobiluncus spp.) (16). A Nugent score (NS) of 0 to 3 is classified as the presence of normal flora, an NS of 4 to 6 is classified as the presence of an intermediate increase in flora (intermediate flora), and an NS of 7 to 10 is classified as BV. Study: J Clin Microbiol. 2005 Mar;43(3):1304-8. PMID: 15750100