What are the possible causes of vaginal white discharge without a foul smell in a female patient?

White Vaginal Discharge Without Foul Smell: Diagnostic Approach

White vaginal discharge without foul odor most likely represents either vulvovaginal candidiasis or physiologic discharge, and you should immediately check vaginal pH and perform microscopy to differentiate between these conditions.

Initial Point-of-Care Testing Algorithm

The absence of foul smell significantly narrows your differential diagnosis, as it effectively excludes bacterial vaginosis and trichomoniasis in most cases 1, 2.

Step 1: Measure Vaginal pH

• pH <4.5 strongly suggests vulvovaginal candidiasis or normal physiologic discharge 1, 2
• pH >4.5 would indicate bacterial vaginosis or trichomoniasis (though these typically have odor) 1, 3

Step 2: Perform Microscopy

• Prepare 10% KOH mount to examine for yeast or pseudohyphae 1, 2
• Prepare saline wet mount to examine for clue cells (bacterial vaginosis) or motile trichomonads 1, 4
• KOH microscopy detects candidiasis in 50-70% of cases 5, 3

Step 3: Perform Whiff Test

• Apply 10% KOH to discharge and assess for fishy odor 1, 3
• Negative whiff test (expected with white, non-odorous discharge) further supports candidiasis or physiologic discharge 1

Most Likely Diagnoses

Vulvovaginal Candidiasis (Primary Consideration)

• Presents with thick, white "cottage cheese-like" or "curdled" discharge 1, 5
• No odor present 1, 3
• Normal pH (<4.5) 1, 5
• Associated symptoms may include vulvar pruritus, dysuria, and vulvovaginal swelling 3, 6
• Hyperemic vagina with erythematous or excoriated vulva on examination 5
• Candida albicans is most common, but C. tropicalis and C. glabrata are increasingly prevalent 5

Physiologic Discharge (Alternative Consideration)

• If pH <4.5 and all microscopy is negative, this represents normal discharge requiring only reassurance 1
• No treatment indicated for physiologic findings 1

Critical Diagnostic Pitfalls

When Microscopy is Negative

• Culture should be obtained if clinical suspicion for candidiasis remains high despite negative KOH preparation 2, 3
• KOH microscopy has only 50-70% sensitivity, so negative microscopy does not exclude candidiasis 5, 3
• DNA probe testing is available and has higher sensitivity than microscopy 2
• Culture is particularly important for identifying non-albicans Candida species in complicated or recurrent cases 2, 3

Less Likely but Possible Causes

• Bacterial vaginosis can occasionally present without prominent odor 6
• Look for homogeneous, thin, white-gray discharge and clue cells on microscopy 1, 2
• However, the absence of odor makes this diagnosis less likely 1

Treatment Based on Findings

If Candidiasis Confirmed

• Topical azoles or oral fluconazole 150mg single dose are equally efficacious for uncomplicated cases 2, 3
• Use only topical azoles during pregnancy 2
• For recurrent infections: fluconazole 150mg weekly for up to 12 consecutive weeks 5
• Approximately 15% of C. albicans organisms are resistant to clotrimazole and miconazole 5

If All Testing Negative

• Provide reassurance that this represents normal physiologic discharge 1
• No treatment required 1

Essential Testing Summary

You must obtain vaginal pH, KOH preparation, and saline wet mount as minimum diagnostic workup 1, 2. If these are negative but symptoms persist, proceed to culture or DNA probe testing 2, 3. The white color and absence of odor make candidiasis your primary diagnostic consideration, with physiologic discharge as the main alternative 1, 5.