A thin grey-white discharge with a fishy odor is most consistent with which infection?

• A. Genital herpes
• B. Trichomonas vaginalis infection
• C. Candidiasis
• D. Bacterial vaginosis

Answer: (D)

A thin grey-white vaginal discharge with a fishy odor is classic for bacterial vaginosis. The fishy smell comes from volatile amines produced by overgrown anaerobic bacteria when lactobacilli are reduced, and the discharge is typically thin and gray-white with a vaginal pH often above 4.5. Additional clues can include a positive whiff test and clue cells on microscopy.

Genital herpes would present with painful vesicular lesions or ulcers, not a fishy discharge. Candidiasis usually causes thick, white, cottage-cheese–like discharge with itching and irritation. Trichomonas infection commonly yields a yellow-green, frothy discharge with itching and irritation, not the thin, fishy-smelling type described.