Sexually Transmissible Infections in Clinical Practice

9. A Woman wih Increased Vaginal Discharge (1)

Alexander McMillan1, 2  


Department of Genitourinary Medicine, NHS Lothian, Edinburgh Royal Infirmary, Edinburgh, Uk


University of Edinburgh, Edinburgh, Uk

Alexander McMillanFormerly, Consultant Physician, part-time Senior Lecturer



A 21-year-old woman, Jane, attends you as her General Practitioner because she has noted increased vaginal discharge.

A 21-year-old woman, Jane, attends you as her General Practitioner because she has noted increased vaginal discharge.

9.1 What Points in the History Would You Wish to Elicit?

Increased vaginal discharge may be physiological, for example, during periods of stress or sexual arousal, or pathological (Table 9.1).

Table 9.1.

Causes of a pathological vaginal discharge.

Vaginal infections

Endocervical infections


Bacterial vaginosis

Trichomonas vaginalis

Candida spp.

Herpes simplex virus

Human papillomavirus

Neisseria gonorrhoeae

Chlamydia trachomatis


Foreign bodies

Chemical irritants

Atrophic vaginitis


Cervical or vaginal carcinoma

The history can be helpful in the differential diagnosis of increased vaginal discharge. For example, in bacterial vaginosis, the discharge is often described as being white with a fish-like odor that is particularly noticeable after unprotected sexual intercourse. Pruritus vulvae, however, is not a feature of this condition unless there is concurrent infection. The principal symptom of vulvovaginal candidiasis is pruritus vulvae rather than increased vaginal discharge. Jane should therefore be asked about the character of the discharge, any associated odor, and whether or not there is vulval itch. She should be asked if she has been sexually active, and if so the taking of a careful sexual history is important to ascertain her risk of a sexually transmitted infection (see Case 2).

She should, of course, be asked about the date of her last period, if it was of normal duration and character, and her menstrual cycle.

Jane tells you that the discharge is milky in color but there is no abnormal smell after intercourse; she has not had vulval irritation. Her last menstrual period had been about 2 weeks previously, it had occurred at the expected time and had been of usual duration. She has had a boyfriend, Richard, for the past 7 months, and during that time they have been having regular sexual intercourse. Her partner always uses condoms for vaginal intercourse, but oral sex is unprotected. Richard is Jane’s first and only sexual partner.

9.2 What is the Most Likely Diagnosis?

The history is strongly suggestive of bacterial vaginosis. One of the symptoms – odor after sexual intercourse – is absent, but this can be explained by the lack of contact of the vaginal secretions with seminal fluid (Richard wears a condom for vaginal intercourse).

You examine Jane, and find a milky-white vaginal discharge that has pooled at the introitus (Fig.9.1 )When you inspect the vaginal walls after having passed a speculum, you note that they are covered with a homogeneous white discharge. The vaginal mucosa, however, does not appear inflamed. The cervix appears normal.


Figure 9.1.

White discharge at introitus.

9.3 Is Bacterial Vaginosis Still the Most Likely Diagnosis?

The clinical features are characteristic of bacterial vaginosis and suffice to make the diagnosis. The character of the discharge is in keeping with bacterial vaginosis. In trichomoniasis, the discharge is usually yellow-green in color, and in many women the vagina is erythematous and edematous. Occasionally (in less than 5% of women), the cervix shows punctuate hemorrhage sometimes with superficial ulceration – the so-called “strawberry cervix.” In women with vaginal candidiasis, the introitus and vagina are often inflamed, and a lumpy, white discharge, often adherent to the vaginal walls, is usually seen.

9.4 If You Wished to Clinch the Diagnosis, What Bedside Tests Might You Undertake?

The pH of the vaginal discharge can be measured by smearing some of the discharge on to a strip of narrow-range pH paper (pH 4.0–6.0). The normal pH of vaginal secretions is ≤4.5, but in bacterial vaginosis, it is >5.0. Note that it is important to avoid the alkaline cervical secretions, and the test is invalid in the presence of blood or seminal fluid.

Another test that can be undertaken is the “sniff test.” This is performed by suspending some vaginal discharge in a drop of 10% potassium hydroxide on a glass slide held immediately under the nose. An ammoniacal odor can be recognized. The test, however, is subjective and is not recommended in clinical practice.


There is no place for culture of vaginal material in the diagnosis of bacterial vaginosis. The bacteria associated with this condition are constituents of the normal flora, albeit in smaller concentrations. If the diagnosis is to be confirmed, say on account of recurrent symptoms, a specimen of vaginal discharge can be sent to the laboratory in transport medium with instructions to examine a saline-mount preparation and a Gram-stained smear only.

9.5 What Would You Expect to See If You Examined Microscopically a Gram-stained Smear of the Discharge?

Lactobacilli that appear as Gram-positive rods predominate in the normal vaginal flora (Fig. 9.2). In bacterial vaginosis, the lactobacilli are reduced in number or are absent, the flora consisting of Gram-positive cocci, Gram-negative rods, and Gram-variable curved rods. These organisms are often found adherent to the surface of epithelial cells (clue cells) (Fig. 9.3).


Figure 9.2.



Figure 9.3.

Bacterial vaginosis – “clue cell.”

9.6 How Would You Manage Your Patient with Bacterial Vaginosis?

An explanation with written information should be provided. She should be told that it is a common vaginal condition that, for whatever reason, results from overgrowth of organisms that are normally present in the vagina in small concentrations. It is important to stress that it is not a sexually transmitted infection. The underlying cause is still uncertain, but hormonal factors may play a role. Jane should avoid vaginal douching, the use of shower gels and the use of antiseptic lotions in her bath – factors known to be associated with the condition. Table 9.2 shows the antimicrobial drug regimens that are generally available for the treatment of bacterial vaginosis. Metronidazole by mouth, either as a course or in a single dose is the treatment of choice.

Table 9.2.

Drug regimens for the treatment of bacterial vaginosis.

Metronidazole 400–500 mg twice daily for 5–7 daysa




Metronidazole 2 g as a single oral dosea




Metronidazole 0.75% gel instilled into the vagina nightly for 7 days




Clindamycin 2% cream instilled into the vagina nightly for 7 daysb




Clindamycin capsules 300 mg twice daily by mouth for 7 daysc


aPatients must be warned of the interaction between alcohol and metronidazole (see Case 10).

bMay affect the integrity of latex condoms.

cMay be associated with antibiotic-associated diarrhea.

Each regimen is very effective. Recurrence, however, is common, and may require further courses of treatment.

Although Jane is in a regular relationship, and has had no other partners, it might be worth offering testing for at least chlamydial infection.

9.7 How Would You Manage Her Sexual Partner?

There is no evidence that the organisms of bacterial vaginosis are sexually transmitted, and so there is no advantage in treating Richard.

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