This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Sexually Transmitted Disease in the Female, Subject name: Gynaecology & Obstetrics
Whiff test is positive in: 
Select and explain. 
A. Candidians, B. Chlamydial infection, C. Trichomonas vaginitis, D. HSV infection
C: Trichomonas vaginitis
Answer: C: Trichomonas vaginitis 
Explanation: Ans. is c, i.e. Trichomonas infectionRef: Williams Gynae 3rd/ed, p52* Whiff Test:Vaginal discharge +10% KOH gives a Fishy odour.This test is characteristic of BV with vaginal pH >4.5 and this stems from diminished acid production by bacteria.Similarly Trichomonas vaginals infection is also associated with anaerobic overgrowth & resultant elaborated lamines.Thus women diagnosed with bacterial vaginosis should have no microscopic evidence of trichomoniasis