Bacterial Vaginosis
Print Friendly, PDF & Email

almostadoctor app banner for android and iOS almostadoctor iPhone, iPad and android apps almostadoctor iOS app almostadoctor android app


Bacterial vaginosis is THE most common cause of pathological vaginal discharge.
Bacterial vaginosis can be caused by an overgrowth of many types of bacteria, usually anaerobes. There is alos often a decrease in the number of lactobacilli.
Bacterial vaginosis is not sexually transmitted.


  • Affects 10% of women in the UK, but most cases are asymptomatic


  • A smelly (fishy) discharge, usually white / gray in colour. This idscharge is made up of waste products produced by the colonising anaerobes.
  • Vaginal itch (not in all cases)
  • Not usually inflamed


  • Whiff test (yes, really!) – potassium hydroxide (KOH) is added to a sample of the vaginal discharge. If a strong fishy odour is produced – the test is positive for bacterial vaginosis
  • pH – >4.5
  • Triple swabs (chlamydia, gonorrhoea, and a ‘general’ swab for culture)
    • Microscopy – reduced levels of lactobacilli, and increased levels of other bacterial agents, leukocytes absent, presence of clue cells
    • Culture – to define the predominant causatory agent
Clue cell - see in bacterial vaginosis
Clue cell – see in bacterial vaginosis.


Trichomoniasis is the only other likely cause of an offensive discharge, but this is usually yellow, and on microsocpy shows the prescence of protozoa with flagella


  • Increased risk of pre-term labour
  • Intra-amniotic infection
  • Increased susceptibility to HIV
  • Post-termination sepsis


  • Metronidazole PO – one-off dose – 2g
  • Clindamycin – 2% cream – apply once at night to the vagina for 7 days
    • If recurrent problems, then treating the partner may resolve the situation


  • Murtagh’s General Practice. 6th Ed. (2015) John Murtagh, Jill Rosenblatt
  • Oxford Handbook of General Practice. 3rd Ed. (2010) Simon, C., Everitt, H., van Drop, F.
  • Beers, MH., Porter RS., Jones, TV., Kaplan JL., Berkwits, M. The Merck Manual of Diagnosis and Therapy

Read more about our sources

Related Articles

Dr Tom Leach

Dr Tom Leach MBChB DCH EMCert(ACEM) FRACGP currently works as a GP and an Emergency Department CMO in Australia. He is also a Clinical Associate Lecturer at the Australian National University, and is studying for a Masters of Sports Medicine at the University of Queensland. After graduating from his medical degree at the University of Manchester in 2011, Tom completed his Foundation Training at Bolton Royal Hospital, before moving to Australia in 2013. He started almostadoctor whilst a third year medical student in 2009. Read full bio

Leave a Reply