Question

Which one of the following solutions is used to disinfect flexible endoscopes?

• A. 10% chlorhexidine
• B. Absolute alcohol
• C. 2% Glutaraldehyde
• D. 5% Peracetic acid

Hint:

Think about which agent gives high-level disinfection without damaging heat-sensitive optics.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
Flexible endoscopes are heat-sensitive instruments built around fibreoptic bundles and long narrow internal channels, so they cannot be sterilised by autoclaving like metal surgical instruments. The question is asking which chemical agent is the correct one for reprocessing this type of scope between patients.

Step 2: Key Concept or Approach:
By the Spaulding classification, an endoscope is a semi-critical item because it touches intact mucosa but not sterile tissue or blood, so it needs high-level disinfection rather than full sterilisation. The chemical used must kill vegetative bacteria, mycobacteria, fungi and most viruses within a practical exposure time, without damaging the optics, lenses or flexible sheath of the scope.

Step 3: Working Through the Options:
2% Glutaraldehyde is the classic high-level disinfectant for flexible endoscopes: soaking the scope in it for roughly 20-30 minutes gives reliable microbicidal activity while being compatible with the delicate materials the instrument is made of, which is why it became the worldwide standard for endoscope reprocessing. 10% chlorhexidine is only a low-to-intermediate level antiseptic used on skin and mucous membranes; it is not sporicidal or reliably mycobactericidal, so it cannot be relied on to disinfect a scope that has been inside a patient's gut or airway. Absolute alcohol evaporates too quickly to maintain a useful contact time inside the long, narrow channels of an endoscope, and it also fixes residual protein and organic debris onto the surface rather than dissolving it, which can trap organisms instead of killing them. 5% peracetic acid, as worded here, is not the standard formulation used for this purpose - peracetic acid disinfection is normally run at a much lower working concentration and needs specific automated reprocessing systems, so it is not the agent intended by this question.

Step 4: Conclusion:
The correct option is 2% Glutaraldehyde, the standard high-level disinfectant solution used for flexible endoscopes.