A case control study of anovaginal distance and bacterial vaginosis

We aimed to test the hypothesis that a short anovaginal distance may increase the risk of bacterial vaginosis (BV) due to faecal contamination and disruption of the vaginal microbiota. Women attending two sexually transmitted infection (STI) clinics in Baltimore, Maryland, USA, who complained of a vaginal discharge were asked to participate in a study to measure mucosal immune responses. In this pilot study of all enrolled women, a small plastic ruler was used to measure the anatomic distance from the posterior fourchette to the anus with the participant in the lithotomy position. Cases of BV, defined by Amsel's clinical criteria (n = 62), were compared with controls (n = 31) without BV. We used linear and logistic regression models to adjust for potential confounders. A total of 93 women were recruited (median age 28.6 years, 93% black, 4.4% gonorrhoea infection, 7.4% chlamydia infection, 8.6% trichomonas infection, 67% BV diagnosed). Mean anovaginal distance was 3.22 cm (SD: 0.74, range 1.8-5.2) for controls and 3.37 cm (SD: 0.76, range: 1.8-5.7) for cases (P = 0.38). There was no difference between cases and controls when comparing median values, quartiles and after adjusting for potential confounders. Among high-risk women with multiple co-infections, there was no association between anovaginal distance and clinical diagnosis of BV.