Table 3. Comparison of Amsel, Nugent, and Hay/Ison criteria (adapted from Hainer and Gibson) for bacterial vaginosis.

	Amsel’s criteria	Nugent’s criteria	Hay/Ison’s criteria
Type	Both clinical and lab investigation	Lab investigation	Lab investigation
Diagnosis time	Rapid	Long	Long
Expertise required	Clinicians	Seasoned pathologists and lab technicians	Knowledgeable laboratory technicians
Lab requirements	Low	High	Moderate
Grading system	When three of the four criteria are met, the diagnosis is considered verified: (a) Narrow, uniform grayish-white discharge is seen. (b) Vulval pH is more than 4.5 (c) Positive Whiff amine test and potassium hydroxide (KOH) test. (d) 20% or more of clue cells seen on a saline wet mount	Score 0-4: Common vegetation. Score 4-6: intermediate. Score 7 and above: Bacterial vaginosis	Category 1: Normal flora (Lactobacillus only) Category 2: intermediate (Lactobacillus = Gardnerella) Category 3: Bacterial vaginosis (Lactobacillus < Gardnerella)