How can I differentiate between a yeast infection and other causes of vaginitis in a primary care setting?

To differentiate between a yeast infection (vulvovaginal candidiasis) and other causes of vaginitis in primary care, consider the following clinical features and investigations:

• Symptoms: Yeast infections typically present with vulval itching, soreness, and a thick, white, 'cottage cheese'-like vaginal discharge without a strong odour. Other causes of vaginitis, such as bacterial vaginosis or sexually transmitted infections, may present with different discharge characteristics (e.g., fishy odour in bacterial vaginosis) and additional symptoms like unpleasant smell or pain on urination NICE CKS,NICE NG201.
• Clinical examination: Look for vulval erythema and swelling which are common in candidiasis. Other causes may have different signs or less vulval involvement NICE CKS.
• Avoid presumptive treatment without confirmation if diagnosis is uncertain: If there is doubt about the cause of symptoms, especially in pregnancy or recurrent cases, consider taking a vaginal swab for microscopy and culture to identify Candida species or other pathogens NICE CKS,NICE NG201.
• Risk factors: Consider underlying conditions such as poorly controlled diabetes or immunocompromise that predispose to candidiasis NICE CKS.
• Response to treatment: Yeast infections typically respond to antifungal therapy (oral fluconazole or intravaginal clotrimazole), whereas other causes require different treatments NICE CKS.

Summary: Differentiation relies on clinical history, symptomatology, examination findings, and, when necessary, microbiological investigations. Vaginal swabs should be considered if diagnosis is unclear or symptoms persist despite treatment NICE CKS,NICE NG201.