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


METHODS
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.


CONCLUSIONS
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.
Verstraelen
Hans
H
Department of Obstetrics and Gynaecology, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium.
Verhelst
Rita
R
Roelens
Kristien
K
Claeys
Geert
G
Weyers
Steven
S
De Backer
Ellen
E
Vaneechoutte
Mario
M
Temmerman
Marleen
M
D000328:Adult; D005260:Female; D006094:Gram-Positive Bacteria / Q000302:isolation & purification; D006801:Humans; D007778:Lactobacillus / Q000302:isolation & purification; D007964:Leukocytosis / Q000175:diagnosis; D011237:Predictive Value of Tests; D011247:Pregnancy; D011256:Pregnancy Outcome; D011261:Pregnancy Trimester, First; D011262:Pregnancy Trimester, Second; D047928:Premature Birth; D011446:Prospective Studies; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D014621:Vagina / Q000382:microbiology*; D014626:Vaginal Smears / Q000145:classification*; D016585:Vaginosis, Bacterial / Q000175:diagnosis