Modified classification of Gram-stained vaginal smears to predict spontaneous preterm birth: a prospective cohort study

Document Type

Article

Department

Obstetrics and Gynaecology (East Africa)

Abstract

Objective

The purpose of this study was to identify women at risk of spontaneous preterm birth through a 4-category Gram-stained vaginal smear method, not restricted to bacterial vaginosis.

Study Design

This was a prospective cohort study correlating Gram-stained vaginal smears in early pregnancy with spontaneous preterm birth. Smears were categorized as ‘normal,’ ‘bacterial vaginosis-like,’ ‘grade I-like’ (atypical gram-positive rods) or ‘purulent grade I’ (lactobacilli-dominated smears showing heavy leukorrhea of unknown cause).

Results

Normal microflora were associated with a 4-fold decreased risk (95%CI 0.1-0.6, P < .001) of spontaneous preterm birth and an abnormal Gram stain with an overall adjusted odds ratio of 5.2 (95%CI 1.8-14.5, P < .001). The sensitivity of vaginal smear diagnosis for preterm birth increased from 25% with conventional scoring up to 70% with these modified criteria.

Conclusion

Accounting for atypical gram-positive bacteria and neutrophils on Gram-stained vaginal smears may identify a larger proportion of women at risk of preterm birth compared to diagnosis of bacterial vaginosis alone.

Comments

This work was published before the author joined Aga Khan University.

Publication (Name of Journal)

American Journal of Obstetrics and Gynecology

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