Aerobic vaginitis - underestimated risk factor for cervical intraepithelial neoplasia

The aim of this study is to analyse the association between vaginal microbiota and the histological finding of CIN. From July 2016 until June 2017, we included 110 consecutive patients with abnormal cervical cytology results referred for colposcopy to Riga East Clinical University Hospital Outpatient department in the study group. 118 women without cervical pathology were chosen as controls. Certified colposcopists performed interviews, gynaecological examinations and colposcopies for all participants. Material from the upper vaginal fornix was taken for pH measurement and wet-mount microscopy. Cervical biopsy samples were taken from all subjects in the study group and in case of a visual suspicion for CIN in the control group. Cervical pathology was more often associated with smoking (34.6% vs. 11.0%, p <0.0001), low education level (47.2% vs. 25.5%, p = 0.001), increased vaginal pH (48.2% vs. 25.4%, p < 0.0001), abnormal vaginal microbiota (50% vs. 31.4%, p = 0.004) and moderate to severe aerobic vaginitis (msAV) (13.6% vs. 5.9%, p = 0.049) compared to controls. The most important independent risk factors associated with CIN2+ were smoking (OR 3.04 (95% CI 1.37–6.76), p = 0.006) and msAV (OR 3.18 (95% CI 1.13–8.93), p = 0.028). Bacterial vaginosis (BV) was found more often in CIN1 patients (8/31, 25.8%, p = 0.009) compared with healthy controls (8/118, 6.8%), or CIN2+ cases (8/79, 10.1%). In the current study msAV and smoking were the most significant factors in the development of CIN in HPV-infected women, especially high grade CIN. We suggest that AV changes are probably more important than the presence of BV in the pathogenesis of CIN and progression to cervix cancer and should not be ignored during the evaluation of the vaginal microbiota.