Full guidance on the clinical features, diagnosis and treatment of bacterial vaginosis can be found in the NICE Clinical Knowledge.
Summary at this address: https://cks.nice.org.uk/bacterial-vaginosis
In essence non pregnant women with symptoms suggestive of bacterial vaginosis do not require confirmation of diagnosis before empirical treatment. Diagnosis is only required in pregnant women and those where there is treatment failure. Should this be the case pH testing of the discharge should be performed if possible for an immediate result. If not a slide can be sent to the laboratory using the procedure below.
Slides and transport boxes are available from specimen reception and the test can be sent by any staff member trained in speculum examination.
The Laboratory will perform a gram stain looking for clue cells and changes in bacterial morphotypes, in particular the characteristic absence of lactobacilli and their replacement with gram variable or gram negative rods in line with Hay Ison criteria. A report will be issued stating the grade according to Hay’s criteria and a clear comment indicating degree of likelihood of bacterial vaginosis.