Bacterial vaginosis laboratory findings
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
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Overview
Laboratory Findings
In clinical practice, the diagnosis of bacterial vaginosis is based on the presence of at least three Amsel criteria. Usually vginal swabs following speculum examination will be tested for:
- Whiff test: A small amount of an alkali is added to a microscope slide that has been swabbed with the discharge—a 'fishy' odour is a positive result for bacterial vaginosis.
- Loss of acidity: A swab of the discharge is put onto litmus paper to check the acidity. A positive result for bacterial vaginosis would be a pH>4.5 (normally slightly acidic with a pH of 3.8–4.2).
- Clue cells: epithelial cells coated with bacteria (under microscopic examination of the discharge)
In research studies, the use of Nugent or Hay/Ison criteria to evaluate a Gram-stained smear of vaginal discharge is the diagnostic standard.
Gram Satin
Gold standard for diagnosis of bacterial vaginosis is Garm stain vaginal discharge.[1]
Cytology
The Papanicolaou smear is not reliable for diagnosis of bacterial vaginosis.[2]
Culture
Vaginal culture has no role in diagnosis of bacterial vaginosis.
Electrolyte and Biomarker Studies
Vaginal swabs following speculum examination will be tested for:
- Whiff test: A small amount of an alkali is added to a microscope slide that has been swabbed with the discharge—a 'fishy' odour is a positive result for bacterial vaginosis.
- Loss of acidity: A swab of the discharge is put onto litmus paper to check the acidity. A positive result for bacterial vaginosis would be a pH>4.5 (normally slightly acidic with a pH of 3.8–4.2).
- Clue cells: epithelial cells coated with bacteria (under microscopic examination of the discharge)
Other Diagnostic Criteria
An alternative is to use a Gram stained vaginal smear, with the Hay/Ison criteria or the Nugent criteria.[3][4]
Hay/Ison Criteria
The Hay/Ison criteria are defined as follows: [5]
| Grading | Definition |
|---|---|
| Grade 0 | No bacteria present |
| Grade 1 | Lactobacillus morphotypes predominate |
| Garde 2 | Mixed flora with (some lactobacilli, gardnerella,or mobiluncus morphotypes present) |
| Garde 3 | Predominantly gardnerella and/or mobiluncus morphotypes (few or absent lactobacilli) |
| Garde 4 | Gram-positive cocci predominate |
- Grade 3 is diagnostic
Nugent Criteria
The standard for research are the Nugent Criteria.[4]
| Score | 0 | 1 | 2 | 3 | 4 |
|---|---|---|---|---|---|
| Lactobacillus morphotypes | >30 | 15-30 | <14 | <1 (this is an average) | 0 |
| Gardnerella/Bacteroides morphotypes | 0 | <1 (this is an average) | 1-4 | 5-30 | >30 |
| Curved Gram variable rods | 0 | <5 | >5 |
In this scale a score of 0-10 is generated from combining three other scores. It is time consuming and requires trained staff but is has high interobserver reliability:
- 0–3 is considered negative for bacterial vaginosis
- 4–6 is considered intermediate
- 7+ is considered indicative of bacterial vaginosis
References
- ↑ Nugent RP, Krohn MA, Hillier SL (1991). "Reliability of diagnosing bacterial vaginosis is improved by a standardized method of gram stain interpretation". J Clin Microbiol. 29 (2): 297–301. PMC 269757. PMID 1706728.
- ↑ Greene JF, Kuehl TJ, Allen SR (2000). "The papanicolaou smear: inadequate screening test for bacterial vaginosis during pregnancy". Am J Obstet Gynecol. 182 (5): 1048–9. PMID 10819823.
- ↑ Ison, CA; Hay, PE (2002), "Validation of a simplified grading of Gram stained vaginal smears for use in genitourinary medicine clinics", Sex Transm Infect, 78: 413–415
- ↑ 4.0 4.1 Nugent, R. P., M. A. Krohn, and S. L. Hillier (1991). "Reliability of diagnosing bacterial vaginosis is improved by a standardized method of Gram stain interpretation". J. Clin. Microbiol. 29: 297&ndash, 301.
- ↑ Guideline Clearing House. "2002 national guideline for the management of bacterial vaginosis". Unknown parameter
|http://www.guideline.gov/summary/summary.aspx?ss=ignored (help)