**Question:** Amsel criteria does not include:

A. Vaginal pH measurement
B. Thick pus cells
C. Staphylococcus aureus sensitivity testing
D. Silver nitrate stain

**Core Concept:** The Amsel criteria are a set of diagnostic criteria for bacterial vaginosis (BV). They were developed by Dr. Richard Amsel in 1983 and are widely used in clinical practice. The criteria include four main signs:

1. **Amsel 1: A clue cell** - A clue cell is a polymorphonuclear neutrophil that extends its cytoplasm beyond the nucleus, indicating an increased concentration of these cells in the vaginal secretions. This is a direct observation of the presence of BV.
2. **Amsel 2: Thick, homogenous, white discharge** - This is a characteristic feature of BV and can be assessed visually or with a speculum.
3. **Amsel 3: A pH greater than 4.5** - Vaginal pH measurement is used as a supportive test for BV diagnosis.
4. **Amsel 4: Presence of clue cells on wet mount** - A wet mount is a simple, rapid, and inexpensive method for detecting clue cells and diagnosing BV.

**Why the Correct Answer is Right:** The Amsel criteria include only three out of the four signs mentioned above: clue cell, thick white discharge, and pH greater than 4.5. The correct answer is right because it highlights that the Amsel criteria do not include a specific test for BV diagnosis.

**Why Each Wrong Option is Incorrect:**

A. Vaginal pH measurement (Option D) is a supportive test for BV diagnosis, but not a sign of BV itself. A pH greater than 4.5 is one of the criteria for Amsel's criteria, not an Amsel sign.

B. Staphylococcus aureus sensitivity testing (Option C) is not a part of the Amsel criteria. The criteria focus on direct microscopic examination and pH measurement, not bacterial culture or sensitivity testing.

C. Silver nitrate staining (Option D) is used to stain vaginal smears, but it is not mentioned in the Amsel criteria. The criteria rely on visual examination, pH measurement, and wet mount preparation for clue cells.

**Clinical Pearl:** Amsel criteria are essential in diagnosing BV and can be used in clinical practice to guide management decisions. However, they are not comprehensive and should be combined with other clinical findings and tests (e.g., wet mount for clue cells, pH measurement, and visual examination) for accurate diagnosis of BV. Including more tests (e.g., bacterial culture or sensitivity testing) may lead to false-positive or false-negative results, making the diagnosis unreliable.