In Modified Knott's technique, what mixture is prepared first?

In Modified Knott's technique, what mixture is prepared first?

• A. 1 ml blood with 9 ml 2% formalin
• B. 9 ml 2% formalin with 1 ml blood
• C. 5 ml blood with 5 ml saline
• D. 2 ml blood with 8 ml formalin 3%

Answer: (A)

The essential idea is to lyse red blood cells while preserving the microfilariae so they can be concentrated and seen clearly under the microscope. To achieve that, you mix a small amount of blood with a large volume of fixative. The standard first step is 1 mL of blood added to 9 mL of 2% formalin. This 1:9 ratio efficiently lyses the red cells without diluting or harming the parasites, so after centrifugation the sediment concentrates the microfilariae for easy viewing. Using saline or a different formalin concentration would not provide the same clearing and concentration effect, and swapping the volumes changes the lysis dynamics and diagnostic visibility.

The essential idea is to lyse red blood cells while preserving the microfilariae so they can be concentrated and seen clearly under the microscope. To achieve that, you mix a small amount of blood with a large volume of fixative. The standard first step is 1 mL of blood added to 9 mL of 2% formalin. This 1:9 ratio efficiently lyses the red cells without diluting or harming the parasites, so after centrifugation the sediment concentrates the microfilariae for easy viewing. Using saline or a different formalin concentration would not provide the same clearing and concentration effect, and swapping the volumes changes the lysis dynamics and diagnostic visibility.