When preparing a direct smear from feces, all of the following liquids can be mixed with feces, except:

When preparing a direct smear from feces, all of the following liquids can be mixed with feces, except:

• A. Tap water
• B. Distilled water
• C. Saline
• D. Hydrogen peroxide

Answer: (D)

When you prepare a direct smear from feces, the goal is to dilute and spread the sample in a way that preserves the morphology of the elements you’re examining. That means using a diluent that is gentle and won’t alter or destroy the cells, cysts, eggs, or bacteria you’re trying to observe. Tap water, distilled water, and saline all serve that purpose: they provide a suitable aqueous medium without chemically damaging the organisms, with saline offering the added benefit of osmotic balance to help preserve cell structures. Hydrogen peroxide, on the other hand, is an oxidizing agent. It can lyse or damage cells and delicate organisms, and its release of gas can create bubbles and disrupt the smear. This makes it unsuitable for direct fecal smears because it can distort the very features you need to visualize.

When you prepare a direct smear from feces, the goal is to dilute and spread the sample in a way that preserves the morphology of the elements you’re examining. That means using a diluent that is gentle and won’t alter or destroy the cells, cysts, eggs, or bacteria you’re trying to observe. Tap water, distilled water, and saline all serve that purpose: they provide a suitable aqueous medium without chemically damaging the organisms, with saline offering the added benefit of osmotic balance to help preserve cell structures.

Hydrogen peroxide, on the other hand, is an oxidizing agent. It can lyse or damage cells and delicate organisms, and its release of gas can create bubbles and disrupt the smear. This makes it unsuitable for direct fecal smears because it can distort the very features you need to visualize.