Bacterial Vaginosis Prevalence: Is It Really Common?

Abstract

Background: Bacterial vaginosis is a common vaginal dysbiosis that may cause abnormal vaginal discharge, malodour and irritation, although some affected women remain asymptomatic. Clinical symptoms alone cannot reliably distinguish bacterial vaginosis from intermediate vaginal flora or other genital tract conditions.

Objective: To determine the prevalence and distribution of Nugent-defined bacterial vaginosis among symptomatic women and assess its association with age, pregnancy status and parity.

Methods: This retrospective, record-based cross-sectional study was conducted at a tertiary-care hospital in Riyadh, Saudi Arabia. Electronic clinical and laboratory records of symptomatic women undergoing vaginal swab examination from 1 September 2023 to 31 August 2024 were reviewed. Gram-stained vaginal smears were classified using the Nugent scoring system as normal flora (score 0–3), intermediate flora (score 4–6) or definite bacterial vaginosis (score 7–10). Data were analysed using IBM SPSS Statistics version 30. Categorical variables were compared using the Pearson chi-square test, with p<0.05 considered statistically significant.

Results: A total of 1,645 vaginal swab specimens were evaluated. The mean age of the women was 28 years, and 252 (15.3%) were pregnant. Definite bacterial vaginosis was identified in 196 women, giving a prevalence of 11.9% (95% CI: 10.4%–13.6%). Intermediate vaginal flora was observed in 920 (55.9%) women, while 529 (32.2%) had normal flora. Overall, 1,116 (67.8%) women had altered vaginal flora. Nugent score distribution differed significantly across age groups (χ²=119.77, p<0.001), with the highest prevalence of definite bacterial vaginosis among women aged 38.1–48 years (24.2%). Definite bacterial vaginosis was more frequent among pregnant than non-pregnant women (28.2% vs 9.0%), with a prevalence ratio of 3.14 (95% CI: 2.42–4.07; p<0.001). Parity was not significantly associated with Nugent score category (p=0.273).

Conclusion: Definite bacterial vaginosis was present in approximately one in eight symptomatic women, whereas intermediate vaginal flora was the predominant microbiological abnormality. Pregnancy and age were significantly associated with Nugent score distribution, while parity showed no significant association. Laboratory confirmation using Nugent scoring may improve diagnostic accuracy and reduce unnecessary empirical antimicrobial treatment.