Vaginal Discharge & Vulvar Pruritus

Introduction to MCCQE1 Preparation

Vaginal discharge and vulvar pruritus are among the most common reasons for gynecological consultation in Canada. For the MCCQE1, candidates must demonstrate the ability to differentiate between physiological discharge and pathological conditions. This topic is central to the Medical Expert and Health Advocate roles within the CanMEDS framework.

Understanding the nuances of the vaginal ecosystem, the impact of sexually transmitted infections (STIs), and non-infectious dermatoses is crucial for success. This guide focuses on the Canadian approach to diagnosis and management, adhering to SOGC (Society of Obstetricians and Gynaecologists of Canada) and PHAC (Public Health Agency of Canada) guidelines.

CanMEDS Corner: Health Advocate

In the context of vaginal symptoms, a physician must advocate for the patient by providing non-judgmental care, addressing sexual health comprehensively, and ensuring access to appropriate screening for STIs, particularly in vulnerable populations.

Physiological vs. Pathological Discharge

Before diagnosing pathology, one must recognize normal physiology.

Physiological Discharge (Leukorrhea): Clear or white, odorless, high viscosity, non-irritating. Quantity varies with the menstrual cycle (highest during ovulation due to estrogen). Acidic pH (<4.5) maintains the Lactobacillus dominant ecosystem.
Pathological Discharge: Change in color, consistency, odor, or volume accompanied by symptoms like pruritus, dysuria, or dyspareunia.

Differential Diagnosis

The differential diagnosis can be broadly categorized into infectious and non-infectious causes.

1. Infectious Vaginitis (The “Big Three”)

These account for the majority of symptomatic cases in Canada.

Bacterial Vaginosis (BV): Dysbiosis with a reduction in Lactobacilli and overgrowth of anaerobes (e.g., Gardnerella vaginalis). Most common cause.
Vulvovaginal Candidiasis (VVC): Yeast infection, typically Candida albicans.
Trichomoniasis: STI caused by the protozoan Trichomonas vaginalis.

2. Other Infectious Causes

Chlamydia trachomatis (Cervicitis)
Neisseria gonorrhoeae (Cervicitis)
Herpes Simplex Virus (Ulcers may cause discharge)

3. Non-Infectious Causes

Atrophic Vaginitis: Genitourinary Syndrome of Menopause (GSM).
Contact Dermatitis: Reaction to latex, lubricants, soaps, or hygiene products.
Lichen Sclerosus / Lichen Planus: Chronic inflammatory dermatoses.
Foreign Body: Retained tampon (malodorous).
Malignancy: Vaginal, cervical, or endometrial cancer (copious, watery, or bloody discharge).

Clinical Evaluation for MCCQE1

Step 1: Focused History

Elicit the “OLDCARTS” of the complaint.

Characteristics: Color, consistency, odor (fishy?).
Associated Symptoms: Itching, burning, dysuria, dyspareunia, spotting.
Sexual History: New partners, condom use, history of STIs.
Hygiene: Douching (risk factor for BV), use of scented products.
Medical Hx: Antibiotic use (risk for VVC), diabetes, pregnancy, immunocompromise.

Step 2: Physical Examination

External Genitalia: Inspect for erythema, fissures, excoriations, lesions (HSV, syphilis), or atrophy.
Speculum Exam:
- Assess vaginal walls for erythema or rugae.
- Observe discharge characteristics (pooled in the fornix).
- Inspect cervix (friability, mucopurulent discharge suggests cervicitis).
Bimanual Exam: Check for cervical motion tenderness (CMT) or adnexal tenderness (suggestive of Pelvic Inflammatory Disease - PID).

Step 3: Office-Based Testing & Investigations

Vaginal pH: Normal is 3.8–4.5.
Whiff Test: Add 10% KOH to discharge; fishy odor = positive (amines released).
Wet Mount Microscopy: Saline (for clue cells, trichomonads) and KOH (for hyphae/spores).
Swabs: NAAT (Nucleic Acid Amplification Test) for Chlamydia/Gonorrhea/Trichomonas if indicated.

Comparative Table: The “Big Three”

This table is high-yield for MCCQE1 preparation.

Feature	Bacterial Vaginosis (BV)	Vulvovaginal Candidiasis (VVC)	Trichomoniasis
Primary Symptom	Malodorous discharge (often no inflammation)	Intense pruritus, burning	Discharge, dysuria, dyspareunia
Discharge	Thin, homogeneous, grey-white	Thick, white, “cottage cheese”, curdy	Frothy, yellow-green, purulent
Odor	Fishy (especially post-coital)	None / Yeasty	Malodorous (sometimes)
Vaginal pH	> 4.5	< 4.5 (Normal)	> 4.5
Whiff Test	Positive	Negative	Often Positive
Microscopy	Clue Cells (>20%), loss of Lactobacilli	Hyphae and/or budding yeast	Motile Trichomonads, WBCs
Inflammation	Minimal (Vaginosis, not Vaginitis)	Significant Erythema, Edema	”Strawberry Cervix” (punctate hemorrhages)

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MCCQE1 Tip: If the pH is normal (<4.5) in a patient with pruritus and discharge, the diagnosis is almost certainly Candida (or physiological/non-infectious). BV and Trichomonas almost always elevate the pH.

Diagnostic Criteria: Amsel Criteria for BV

To diagnose BV clinically, 3 out of 4 must be present:

Homogeneous, thin, grayish-white discharge.
Vaginal pH > 4.5.
Positive Whiff test (amine odor with 10% KOH).
Clue cells on wet mount (>20% of epithelial cells).

Note: Nugent scoring (Gram stain) is the gold standard but rarely used in clinical office settings.

Management (Canadian Guidelines)

Treatment strategies based on PHAC and SOGC recommendations.

Bacterial Vaginosis

Goal: Relieve symptoms. Asymptomatic BV generally does not require treatment unless pregnant (high risk) or undergoing gynecological procedures.

First-Line Therapies (Canada):

Metronidazole: 500 mg PO BID for 7 days.
Metronidazole gel 0.75%: Intravaginal once daily for 5 days.
Clindamycin cream 2%: Intravaginal once daily for 7 days.

Notes:

Advise patients to avoid alcohol during oral Metronidazole therapy (disulfiram-like reaction - though recent evidence questions this, it remains a standard caution).
Partner treatment is not recommended for BV.

Red Flags & Urgent Referrals

⚠️ Clinical Red Flags

Pelvic Pain + Fever + Cervical Motion Tenderness: Suspect PID. Requires aggressive antibiotic therapy to prevent infertility.
Post-menopausal Bleeding: Must rule out Endometrial Cancer.
Persistent Ulcers: Rule out Syphilis, HSV, or Vulvar Cancer.
Recurrent symptoms despite treatment: Consider resistant organisms, non-albicans Candida, or alternative diagnoses (Lichen Sclerosus).

Key Points to Remember for MCCQE1

Pregnancy: BV is associated with preterm labor and premature rupture of membranes. Symptomatic pregnant women should be treated. Asymptomatic screening is controversial but generally not recommended for low-risk pregnancies.
Recurrent VVC: Defined as $\ge$ 4 episodes per year. Requires induction therapy followed by maintenance fluconazole for 6 months.
Atrophic Vaginitis: In post-menopausal women presenting with dryness, pruritus, and dyspareunia, consider topical estrogen (after ruling out other causes).
Canadian Context: Be aware of the availability of OTC treatments (e.g., Canesten/Monistat) and when to advise patients to seek medical care (first episode, pregnancy, recurrence).

Study Checklist

Memorize the Amsel Criteria.
Differentiate the microscopy findings (Clue cells vs. Hyphae vs. Trichomonads).
Know the pH cut-offs.
Understand the treatment of VVC in pregnancy (Topical only!).
Review the STI reporting requirements in Canada.

Sample Question

Scenario

A 26-year-old female presents to her family physician complaining of a vaginal discharge that has been present for the last week. She describes the discharge as thin and grayish-white with a noticeable odor, which she notes is worse after sexual intercourse. She denies any vulvar itching or burning. She is sexually active with one male partner and uses an intrauterine device (IUD) for contraception.

On physical examination, the vulva appears normal with no erythema or fissures. Speculum examination reveals a thin, homogeneous, grey-white discharge coating the vaginal walls. The cervix is not inflamed. Vaginal pH is 5.5. A whiff test is positive.

Which one of the following is the most appropriate initial pharmacotherapy?

Options

A. Oral fluconazole 150 mg single dose
B. Intravaginal clotrimazole 1% cream for 7 days
C. Oral metronidazole 500 mg BID for 7 days
D. Intramuscular ceftriaxone 250 mg single dose
E. Oral azithromycin 1 g single dose

Explanation

The correct answer is:

C. Oral metronidazole 500 mg BID for 7 days

Detailed Explanation: The clinical presentation is classic for Bacterial Vaginosis (BV).

Evidence: The patient meets Amsel criteria:
1. Thin, homogeneous discharge.
2. Vaginal pH > 4.5 (hers is 5.5).
3. Positive Whiff test.
4. (Clue cells would likely be seen on microscopy, though not explicitly stated, 3/4 criteria are met clinically).
Symptoms: The “fishy” odor exacerbated by intercourse (alkaline semen releases amines) and lack of inflammatory symptoms (itching/erythema) are hallmark features of BV.

Why the other options are incorrect:

A & B (Fluconazole/Clotrimazole): These are treatments for Vulvovaginal Candidiasis (VVC). VVC typically presents with thick, white “cottage cheese” discharge, intense pruritus, erythema, and a normal pH (<4.5).
D & E (Ceftriaxone/Azithromycin): These are treatments for Gonorrhea and Chlamydia, respectively. While these should be considered in the differential for cervicitis, the patient’s specific signs (homogeneous discharge, high pH, odor) point strongly to BV. Additionally, she lacks signs of cervicitis (mucopurulent discharge, friability).

Canadian Guideline Note: Metronidazole (oral or vaginal gel) or Clindamycin cream are first-line therapies for BV in Canada.

References

Society of Obstetricians and Gynaecologists of Canada (SOGC). Clinical Practice Guideline No. 320: Vulvovaginitis: Screening for and Management of Trichomoniasis, Vulvovaginal Candidiasis, and Bacterial Vaginosis. J Obstet Gynaecol Can. 2015.
Public Health Agency of Canada (PHAC). Canadian Guidelines on Sexually Transmitted Infections. Available online .
Medical Council of Canada (MCC). MCCQE Part I Objectives: Vaginal Discharge.
Bower, J. et al. 2023 Canadian Contraception Consensus. J Obstet Gynaecol Can.