Fixatives

• Fixatives are substances that preserve the morphology of protozoa and prevent further development of certain helminth eggs and larvae.
• What is ratio mixture of stool to fixatives?

  1:3
• How long does fixing with fixatives lasts before processing?

  30 minutes
• What fixative is an all-purpose?

  5% or 10% formalin
• 5% formalin is used for helminth eggs and larvae and 10% for protozoan cysts
• Schaudinn’s Fixative is used with fresh stool specimen or sample from the intestinal mucosal surfaces.
• What is the universal fixative?

  Polyvinyl alcohol (PVA)
• Polyvinyl alcohol is a plastic resin that is normally incorporated into Schaudinn’s fixative.
• What serves as an adhesive for stool material?

  PVA powder
• What fixative substitutes copper sulfate and zinc sulfate mercury?

  Modified PVA
• What are the bases of Modified PVA?


  Copper and Zinc
• Sodium acetate-acetic acid-formalin (SAF) is a liquid fixative much like 10% formalin.
• Sodium acetate-acetic acid-formalin is considered "softer fixative" than what?

  mercuric chloride
• What fixative is considered the best fixative?

  Merthiolate/ Thimerosal-Iodine Formalin (MIF)
• What fixative is a good stain preservative for most kinds and stages of parasites found in feces?

  Merthiolate/Thimerosal-Iodine Formalin (MIF)
• MIF fixative is useful in what surveys?

  field surveys
• MIF fixative is used with all common types of stools and aspirates.