Are you aware that BV is not generally regarded as a sexually transmitted infection; however, the prevalence is higher amongst sexually active women (than non-sexually active women)?


Written by Bukola |Published: 22 |09|2022

Bacterial vaginosis (BV) is the most common cause of abnormal vaginal discharge in women of child-bearing age, but may also be encountered in perimenopausal women.

Women who have sex with women are at increased risk for BV because they share similar lactobacillary types and are more likely to have concordant vaginal flora patterns.

[BASHH, 2012; NICE, 2017; Sherrard, 2018]



Bacterial vaginosis (BV) is characterized by an overgrowth of predominantly anaerobic organisms (such as Gardnerella vaginalis, Prevotella species, Mycoplasma hominis, and Mobiluncus species) and a loss of lactobacilli. The vagina loses its normal acidity, and vaginal pH increases to greater than 4.5.


The normal vaginal pH in a woman of child-bearing age is 3.5–4.5.

A pH greater than 4.5 is suggestive of, but it is not specific for, the diagnosis of BV; raised vaginal pH can also indicate other conditions, such as trichomoniasis.

[BASHH, 2012; NICE, 2017; Sherrard, 2018]



Reported prevalence rates include 5% in a group of asymptomatic college students, 12% in pregnant women attending an antenatal clinic in the UK, and 30% in women undergoing termination of pregnancy [BASHH, 2012]. It is more prevalent in Black women (45–55%) than in Caucasian women (5–15%) [Sherrard, 2018].

The presence of BV during pregnancy varies according to ethnicity and how often a population is screened [NICE, 2017]:

In a cross-sectional study of 13,747 pregnant American women, 8.8% of White women had BV compared with 22.7% in Black women, 15.9% in Hispanic women, and 6.1% in Asian-Pacific Islander women.

In an area in northwest London, screening before 28 weeks of gestation found a BV prevalence of 12%.

The prevalence of BV is higher amongst sexually active women than non-sexually active women, although it is not generally regarded as a sexually transmitted infection.

[BASHH, 2012; Sherrard, 2018] 



  • BV is characterized by a thin, white/grey, homogeneous coating of the vaginal walls and vulva that has a fishy odour. The characteristic appearance of the discharge is not specific for BV but supports the diagnosis.
  • BV is not usually associated with soreness, itching, or irritation. If these symptoms are present consider other diagnoses or co-infection with candidiasis (genital thrush is a symptomatic inflammation of the vagina and/or vulva caused by a superficial fungal infection), or trichomoniasis (sexually transmitted infection (STI) caused by the flagellated protozoan Trichomonas vaginalis).




  • The exact trigger for bacterial vaginosis (BV) is unknown, but symptoms are thought to appear when the vaginal pH raises, creating an alkaline environment which favours the growth of normal and abnormal bacteria [Lazaro, 2013].


    • Factors that raise vaginal pH, includes:
      • The use of vaginal products, such as douches, deodorant, and vaginal washes, and the use of antiseptics, bubble baths, or shampoos in the bath.
      • Menstruation.
      • Presence of semen in the vagina.
    • Copper intrauterine device (it is unclear if this is also the case with the levonorgestrel intrauterine system) [Sherrard, 2018].
    • Ethnicity — BV is more prevalent in Black women (45–55%) than in Caucasian women (5–15%) 
    • Smoking.


  • Factors that increase the risk of developing BV includes:
    • Being sexually active — BV is not a sexually transmitted infection (STI), but being sexually active or having concurrent STIs increases the risk of developing BV.
    • Recent change in sexual partner.
    • Certain sexual practices, for example receiving oral sex. In addition, women who have sex with women share similar lactobacillary types, are more likely to have concordant vaginal flora patterns, and are at increased risk for BV [Sherrard, 2018].

  • Factors that reduce the risk of developing BV include :
    • Hormonal contraception — a systematic review and meta-analysis found that combined hormonal contraception and progesterone-only contraception are associated with a reduction in the prevalence and incidence of BV [Vodstrcil, 2013].
    • Consistent condom use.
    • Circumcised partner.




  • Women with bacterial vaginosis (BV) are at increased risk of acquiring sexually transmitted infections (STIs) 
    • Women with BV have a 2-fold increased risk of acquiring HIV compared with women without BV, and HIV positive women with BV have a 3-fold risk of transmitting HIV [Sherrard, 2018].
    • Women with BV also have a 1.5 to 2-fold risk of acquiring chlamydia and gonorrhoea, a 9-fold risk of trichomoniasis, and a 2-fold risk of herpes simplex virus (HSV)-1 compared with women without BV [Sherrard, 2018].
    • A prospective study of women with clinically suspected pelvic inflammatory disease (PID) reported significant association between the presence of BV-associated bacteria and the presence of endometritis and recurrent PID [Haggerty, 2016Sherrard, 2018].

  • BV is also associated with several obstetric and gynaecologic complications, including :
    • Late miscarriage.
    • Pre-term labour and delivery.
    • Pre-term premature rupture of membranes.
    • Spontaneous abortion.
    • Low birthweight baby.
    • Postpartum endometritis.
    • Post caesarean delivery wound infections.
    • Post-surgical infections.
    • Subclinical PID.


  • Preventative measures include:
    • Increased use of condoms.
    • Avoidance of drugs and alcohol when having sex.




  • use water and plain soap to wash your genital area
  • have showers instead of baths


  • do not use perfumed soaps, bubble bath, shampoo or shower gel in the bath
  • do not use vaginal deodorants, washes or douches
  • do not put antiseptic liquids in the bath
  • do not use strong detergents to wash your underwear






Patient information is available from:










  • BASHH (2011) UK national guideline on the management of gonorrhoea in adults 2011. British Association for Sexual Health and HIV. http://www.bashh.org [Free Full-text]
  • BASHH (2012) UK national guideline for the management of bacterial vaginosis 2012. British Association for Sexual Health and HIV. http://www.bashh.org [Free Full-text]
  • BASHH (2015) UK national guideline for the management of infection with Chlamydia trachomatis. British Association for Sexual Health and HIV. http://www.bashh.org [Free Full-text]
  • Haggerty, C.L., Totten, P.A. and Tang, G. et al. (2016) Identification of novel microbes associated with pelvic inflammatory disease and infertility. Sexually Transmitted Infections 92(6), 441-446.
  • Lazaro, N. (2013) Sexually transmitted infections in primary care. Royal College of General Practitioners and British Association for Sexual Health and HIV. http://www.bashh.org [Free Full-text]
  • NICE (2017) Antenatal care for uncomplicated pregnancies. National Institute for Health and Care Excellence. http://www.nice.org.uk [Free Full-text]
  • PHE (2013) Management and laboratory diagnosis of abnormal vaginal discharge. Quick reference guide for primary care. Public Health England. [Free Full-text]
  • Sherrard, J., Wilson, J. and Donders G. et al. (2018) 2018 European (IUSTI/WHO) guideline on the management of vaginal dischargehttp://www.iusti.org [Free Full-text]
  • Vodstrcil, L., Hocking, J. and Law, M. et al. (2013) Hormonal contraception is associated with a reduced risk of bacterial vaginosis: a systematic review and meta-analysis. PLoS One 8(9). [Free Full-text]