1. Preparing thin and thick blood films with capillary or venous blood

Transcription

1 Methods in Parasitology 1. Preparing thin and thick blood films with capillary or venous blood Swiss Tropical Institute, Basel April 2005

2 1.0 Preparing thin and thick blood films Contents 1.1 Preparatory steps 1.4 Using finger-prick blood 1.8 Preparing thin films 1.13 Preparing thick films 1.23 Using venous blood Production Team: Yvette Endriss, Elisabeth Escher & Birgit Rohr Prof. Hanspeter Rohr (NeoCortex Foundation) Prof. Niklaus Weiss (STI)

3 1.1 Preparing thin and thick blood films Materials for finger pricks: Disinfectant Swabs Microscope slides (cleaned with alcohol) Sterile lancets Special slide as spreader Gloves (Pay attention to general precautions when handling blood!)

4 1.2 Preparing thin and thick blood films Prepare the microscope slides

5 1.3 Preparing thin and thick blood films Use microscope slides with or without frosted end

6 1.4 Preparing thin and thick blood films Finger-prick (capillary blood) With the patient s left hand, palm upwards, select the third finger. (The big toe can be used with children. The thumb should never be used for adults or children). Use cotton wool lightly soaked in alcohol to clean the finger, using firm strokes to remove grease from the ball of the finger. Let finger air-dry.

7 1.5 Preparing thin and thick blood films Finger-prick (capillary blood) With a sterile lancet puncture the ball of the finger using a quick rolling action. Clip

8 1.6 Preparing thin and thick blood films Finger-prick (capillary blood) By applying gentle pressure to the finger express the first drop of blood and wipe it away with dry cotton wool. Make sure no strands of cotton remain on the finger.

9 1.7 Preparing thin and thick blood films Finger-prick (capillary blood) Working quickly with capillary blood and handling clean slides only by the edges, collect the blood as follows: Apply gentle pressure to the finger and collect a single small drop of blood about the size on the end of the slide. This is for thin film.

10 1.8 Preparing thin and thick blood films Thin films (capillary blood) Using another clean slide as a spreader, and with the slide with the blood drops resting on a flat, firm surface, touch the small drop with the spreader (1) and allow the blood to run along its edge. Firmly push the spreader along the slide (2), away from the drops, keeping the spreader at an angle of 45. Make sure the spreader is in even contact with the surface of the slide. (Look at clip on next slide) Left hand Parasites 2 Slide 1 Blood Right hand 45 Slide Base

11 1.9 Preparing thin and thick blood films Thin films (capillary blood) Clip

12 1.10 Preparing thin and thick blood films Possible mistakes: This is wrong! This is correct!

13 1.11 Preparing thin and thick blood films Observe right angle! Angle too flat > film too long Angle too steep > film too short

14 1.12 Preparing thin and thick blood films Mistakes: Pressure on spreader too strong > waves Air bubble > Uneven film

15 1.13 Preparing thin and thick blood films Thick films (Capillary blood) Apply gentle pressure to the finger and collect two larger drops, about a size, on the slide as shown in the upper picture. Handle the spreader by the edge, using the corner to spread the blood in a circular form with 3-6 movements.

16 1.14 Preparing thin and thick blood films Thick films Faulty handling: Do not use a plastic pipette Do not use a wooden prick

17 1.15 Preparing thin and thick blood films Thick films Check for the right thickness: You should be able to read the newspaper!

18 1.16 Preparing thin and thick blood films Thick films Additional mistakes Thick film too thick Thick film should be round!

19 1.17 Preparing thin and thick blood films Labelling With frosted end use a pencil Without frosted end use diamond pencil

20 1.18 Preparing thin and thick blood films Labelling Faulty handling: Do not use a ball pen Do not use a paper label

21 1.19 Preparing thin and thick blood films Drying Allow the thin film and the thick film to dry in a flat level position protected from flies, dust and extreme heat.

22 1.20 Preparing thin and thick blood films Drying Optional: Use special device to dry thick or thin films For example: Small incubator 37 C Heating plate (not over 37 C)

23 1.21 Preparing thin and thick blood films Drying Do not use a hair dryer or a fan! (Collects the dust)

24 1.22 Preparing thin and thick blood films These slides look o.k.!

25 1.23 Preparing thin and thick blood films These slides look more like art work than useful blood slides!

26 1.24 Preparing thin and thick blood films Venous blood can be used instead of capillary blood Use vacutainers with anticoagulant (EDTA)

27 1.25 Preparing thin and thick blood films For preparing thin and thick films use a glass capillary to drop the ETDA-blood. Do not use a plastic pipette! Clip

28 1.26 Preparing thin and thick blood films Spare glass slides Combination of a thin and a thick film on the same slide.

29 1.27 Preparing thin and thick blood films Spare glass slides Combination of a thin and a thick film on the same slide.