## **Core Concept**
Diagnostic hysteroscopy involves the use of a hysteroscope to visually examine the uterine cavity. The procedure requires a distension medium to allow clear visualization. The choice of distension medium can depend on the type of hysteroscope and the energy modality used, such as bipolar coagulation.

## **Why the Correct Answer is Right**
The correct answer, **D. Normal saline**, is appropriate for diagnostic hysteroscopy when using bipolar coagulation. Bipolar coagulation systems operate effectively in a saline environment, which is isotonic and does not conduct electricity in a way that would interfere with the coagulation process. Normal saline is a suitable distention medium because it allows clear visualization and is compatible with bipolar electrosurgical systems.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Glycine is an amino acid solution used as a distention medium, primarily with monopolar electrosurgical systems. It is not the best choice for procedures using bipolar coagulation because glycine is not an ideal medium for bipolar systems, and its use can lead to fluid overload and electrolyte imbalances if absorbed.
- **Option B:** Dextrose 5% is another solution that can be used for uterine distension. However, it is more commonly associated with monopolar electrosurgery and might not be the first choice for procedures where bipolar coagulation is utilized.
- **Option C:** This option might seem plausible but given the context of bipolar coagulation, it's less relevant.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the choice of distention medium in hysteroscopy can significantly affect the procedure's safety and efficacy, particularly when electrosurgery is involved. For procedures using bipolar coagulation, **normal saline** is a commonly recommended distention medium due to its compatibility with the bipolar system and its isotonic properties.

## **Correct Answer: D. Normal saline**