Proposal of a new cutoff for Nugent criteria in the diagnosis of bacterial vaginosis.

Objectives: Treatment for lower genital tract infections is the major demand for gynecological services in public and private health centers in Brazil. The aims of this study were to evaluate the diagnostic resources proposed by Amsel, comparing them with the microflora evaluation by the Nugent score and thus propose a new cutoff point in this rating score, showing the complementarity of both diagnostic criteria.

Methods: A total of 136 female patients aged between 18 and 69years were evaluated and had their vaginal discharge samples collected.

Results: Diagnosis based on the isolated analysis of the Amsel's criteria may lead clinicians to apply inadequate treatment techniques. When patients were evaluated according to the Amsel criteria, it was seen that the presence of clue cells had a higher Kappa index in the vaginosis diagnosis; when patients were distributed according to the Nugent criteria in relation to each Amsel criterion, it was observed that clue cells differentiate positive patients more efficiently than the Nugent criteria. In the proposed cutoff point, the identification of clue cells complied with pH alterations. It also complied with the positive Nugent score (≥7). However, when clue cells were analyzed by both Amsel and Nugent methods, the diagnostic conclusion was reached once this was the parameter with a higher Kappa value.

Conclusion: The Amsel method could be used as a screening tool whereas the Nugent score could serve as a confirmatory resource of diagnosis, considering a new assessment cutoff point (negative 0-6 and positive ≥7).