1. Phlebotomy Simplified
Third Edition
Chapter 9
Capillary or Dermal Blood Specimens
Copyright © 2019, 2013, 2008 Pearson Education, Inc. All Rights Reserved

2. Chapter Learning Objectives (1 of 2)
9.1 Describe the reasons for acquiring capillary blood specimens for adults, children, and infants. 9.2 List common laboratory tests for which capillary specimens may be collected. 9.3 Explain why capillary blood from a skin/dermal puncture is different from blood taken by venipuncture and the difference’s impact on laboratory tests.

3. Chapter Learning Objectives (2 of 2)
9.4 Identify the proper sites for performing a skin puncture procedure, and explain why it is necessary to control the depth of the incision. 9.5 Describe the procedure for performing a skin puncture. 9.6 Describe the procedure for making an acceptable blood smear/film.

4. Indications for Skin Puncture (1 of 4)
Useful for adults and pediatric patients
Certain tests require small amounts
For neonates and infants, use of capillary blood samples preferred method of collection
If small amounts of blood acceptable for laboratory tests, dermal punctures or “fingerstick” procedures are used

5. Indications for Skin Puncture (2 of 4)
Conditions for Dermal or Fingerstick
Fragile veins
Veins being saved for IV therapy
Multiple unsuccessful venipunctures and tests require small amounts of blood
Home testing
Point-of-care testing (POCT)
Severe burns

6. Indications for Skin Puncture (3 of 4)
Conditions for Dermal or Fingerstick
Obese patients
Thrombotic tendencies
Patient receiving IV therapy in both arms
Patient fearful/anxious about venipunctures
Patient may need only one blood test done on small sample volume

7. Indications for Skin Puncture (4 of 4)
Fingerstick procedures not recommended if:
Testing requires large amounts of blood
Swollen fingers
Dehydrated condition
Poor peripheral circulation
Coagulation studies
Please see Box 9-1 in the textbook.

8. Composition of Capillary Blood
A mixture of blood from:
Arterioles
Venules
Capillaries
Intracellular and interstitial (tissue) fluids

9. Collecting Diagnostic Capillary Blood Specimens
First steps for venipuncture procedure also apply to skin puncture procedure.
Preparation
Identification of patient
Asking about latex allergies and fainting
Hand hygiene
Cleansing the puncture site
Subsequent steps slightly different

10. Supplies for Skin Puncture (1 of 8)
Disposable gloves
Commercially available warming pack, heating pad, or device for warming
Sterile disposable single-use retractable safety puncture device
Disinfectant pads (70% isopropanol)
Sterile, nonlatex bandages, self-adhering bandages, and gauze pads
Glass microscope slides

11. Supplies for Skin Puncture (2 of 8)
Diluting fluids as required by manufacturers
Plastic microcollection tubes
Plastic-coated capillary tubes
Capillary tube sealers or closures
Laboratory request slips or labels
Marking pen
Puncture-proof biohazard discard container

12. Supplies for Skin Puncture (3 of 8)
Skin Puncture Sites
For adults and older children, preferred site is fleshy, central palmar surface of distal phalanx of 3rd or 4th finger of nondominant hand.
Use thickest part of finger, just off-center.
Fingers should not be cyanotic, edematous, or infected
For infants (<1yr) or neonates use, lateral or medial plantar surface of heel.

13. For long description, see slide 58: Appendix A
Figure 9-3
Structures of the Finger and Nail
Note the positioning of the fingertip bone (distal phalanx) and where it lies in proximity to the edge of the skin. Nails are formed like hair, from a root, and grow about 0.1 mm per day. The nail bed is tender, so punctures near the nail’s edge are more painful and not acceptable.
For long description, see slide 58: Appendix A

14. For long description, see slide 59: Appendix B
Figure 9-4
Sites for Dermal Puncture on the Fingers (Fingerstick)
A. The third or fourth finger on the nondominant hand is the preferred choice. B Note that the darkened areas (curved) represent the most suitable puncture sites that avoid the risk of puncturing the bone or nail bed. Keep in mind that each patient is different, and slight adjustments may be required. C. Fingerprint grooves are often hard to see, but, if visible, the dermal puncture or incision should be across the grooves instead of parallel to the grooves. This helps form rounded drops of blood. If the incision is parallel to the grooves, blood tends to run into them and is harder to collect.
For long description, see slide 59: Appendix B

15. Supplies for Skin Puncture (4 of 8)
Skin Puncture Sites Not Recommended
Earlobe
Central arch or posterior curve of infant’s heel
Fingers of a newborn or infant less than 1 year old

16. Supplies for Skin Puncture (5 of 8)
Skin Puncture Sites Not Recommended
Thumb, fifth (pinky) or index (pointer) finger
Swollen, infected, callused, burned, cut, scarred, bruised, previously punctured sites, or sites with rashes
Fingers on the side of a mastectomy

17. Supplies for Skin Puncture (6 of 8)
Warming the Site
Increases arterial blood flow to the area
Commercially available thermal packs
Heated surgical towel or a washcloth heated with warm water to 42°C will not burn the skin
Washing hands with warm water

18. Supplies for Skin Puncture (7 of 8)
Lowering the Arm
Lower patient’s arm
Fingers downward allows gravity to fill capillaries in fingers

19. Supplies for Skin Puncture (8 of 8)
Cleansing the Skin Puncture Site
Cleanse site with a 70% aqueous solution of isopropyl alcohol.
Allow site to thoroughly dry before being punctured.

20. Skin Puncture Procedure (1 of 2)
Skin Puncture Devices
Sterile, disposable, single-use, permanently retractable safety blade or needle
Puncture devices control for variable depth and length, depending patient’s age and weight

21. Skin Puncture Procedure (2 of 2)
Skin Puncture Devices
Average depth of puncture should be mm for adults and less than 2.0 mm for children and infants
Laser devices provide a smaller hole (about 250 µm wide and 1 to 2 mm deep).

22. For long description, see slide 60: Appendix C
Figure 9-2
Supplies for Capillary Blood Collection Devices and Tubes from Two Manufacturers
A. Microvette® Capillary Blood Collection System. Courtesy of Sarstedt, Inc. Newton, NC. B. Microcollection tubes. Courtesy of Greiner Bio-One GmbH, Kremsmunster, Austria
For long description, see slide 60: Appendix C

23. Figure 9-5

24. Basic Skin Puncture for Capillary Blood Collection (1 of 13)
Follow the manufacturer’s instructions.
Remove the puncture device or lancet from packaging.
Let the patient know that he or she will feel a prick.

25. Figure 9-6

26. Basic Skin Puncture for Capillary Blood Collection (2 of 13)
Hold patient’s finger (or heel, in case of an infant) firmly with one hand, with your thumb away from the puncture site, next to patient’s fingernail.
With the other hand, position puncture device perpendicular to the site.

27. Basic Skin Puncture for Capillary Blood Collection (3 of 13)
Activate the release mechanism so the puncture is made quickly.
Orient the cut across the fingerprints to generate a large, round drop of blood.

28. Basic Skin Puncture for Capillary Blood Collection (4 of 13)
Discard the puncture device in a puncture-proof biohazard container.
Wipe away the first drop of blood with clean gauze unless otherwise indicated by manufacturer.

29. Figure 9-9

30. Basic Skin Puncture for Capillary Blood Collection (5 of 13)
Collect second drop of blood by touching it to the tip of microcollection device.
The blood will flow into the tube by capillary action, whereby blood flows freely into the tube on contact, without suction.

31. Figure 9-10

32. Basic Skin Puncture for Capillary Blood Collection (6 of 13)
Gently apply pressure to the finger and hold the puncture site in a downward position while filling tubes.
Do not use excessive milking/massaging of the finger or forceful scooping-up of blood.
Follow the correct order of draw.

33. Basic Skin Puncture for Capillary Blood Collection (7 of 13)
Each type of microcollection laboratory test has different tube and blood volume requirements.
Follow the appropriate manufacturer’s instructions.
Carefully and safely seal microcollection tubes as directed by the manufacturer.

34. Basic Skin Puncture for Capillary Blood Collection (8 of 13)
When filling capillary tubes, do not allow air bubbles to enter the tubes.
Apply gentle pressure as blood drops are collected.
Mix specimens according to the manufacturer’s instructions, usually by gently inverting containers with additives to mix blood with additives.

35. Basic Skin Puncture for Capillary Blood Collection (9 of 13)
Blood smears can also be made from subsequent drops of blood.
Using a clean gauze pad, apply gentle pressure to the site until bleeding has stopped.

36. Figure 9-12

37. Basic Skin Puncture for Capillary Blood Collection (10 of 13)
Label the specimens and outside containers to prepare for transport.
Ask patient to confirm identity of labels.
Discard all other biohazardous supplies before removing gloves.
Remove and dispose of gloves.

38. Basic Skin Puncture for Capillary Blood Collection (11 of 13)
Perform hand hygiene.
Ensure that bleeding has stopped.
Thank the patient before leaving with specimens and remaining supplies.

39. For long description, see slides 61-62: Appendix D
Figure 9-14
Order of Draw Using BD Microtainer Tubes
Courtesy and © Becton, Dickinson and Company
For long description, see slides 61-62: Appendix D

40. Basic Skin Puncture for Capillary Blood Collection (12 of 13)
Filling each tube to correct “fill volume” is important.
Underfilled tubes will have higher concentration of additives and can cause erroneous results.
Overfilled tubes lower concentrations of additives/anticoagulants and may result in clotting.

41. Basic Skin Puncture for Capillary Blood Collection (13 of 13)
Causes of Hemolysis
Not removing residual alcohol at the puncture site
Excessive milking/massaging the finger
Patients have increased blood cell fragility and high- packed cell volume (newborns and infants)
Excessive shaking while mixing

42. Blood Films for Microscopic Slides (1 of 9)
No longer performed in all laboratories.
Used to evaluate morphology (form and structure) of blood cells, for detecting cellular abnormalities, for confirmation, and/or as a back-up method.
Prepared with blood drop.
Slides are stained and evaluated under a microscope.

43. Blood Films for Microscopic Slides (2 of 9)
Prepare and assemble supplies.
Identify the patient properly.
Cleanse your hands, then don gloves.
Perform the skin puncture.
Wipe the first drop of blood away.

44. Blood Films for Microscopic Slides (3 of 9)
Touch the slide to the second drop at approximately 0.5– 1 inch (1.3–2.5 cm) from the end of the slide.

45. Figure 9-15

46. Blood Films for Microscopic Slides (4 of 9)
Place the second (spreader) slide in front of the drop of blood and then pull it slowly into the drop, allowing blood to spread along the width of the slide.

47. Figure 9-20

48. Blood Films for Microscopic Slides (5 of 9)
When the blood spreads almost to the edges, quickly and evenly push the spreader slide forward (not downward) at an angle of approximately 30 degrees.

49. Figure 9-21

50. Blood Films for Microscopic Slides (6 of 9)
Blood films should have a feathered edge.
No ridges, lines, or holes should be visible in the smear.

51. Figure 9-22

52. Blood Films for Microscopic Slides (7 of 9)
Errors often result of too large a drop, too long a delay in spreading drop, not moving spreader slide in straight line, pressing too hard on spreader slide, blowing on slide, or using chipped slide.
Label the slides and prepare them for safe transport to the laboratory.

53. Blood Films for Microscopic Slides (8 of 9)
Discard unusable slides and all biohazardous waste in an appropriate container.
Label slides according to correct ID procedures at your facility.
Thank patient for cooperating, reconfirm identity, allow patient to leave.

54. Blood Films for Microscopic Slides (9 of 9)
Depart with all specimens and all remaining supplies.
Transport and/or deliver the slides to the laboratory.

55. Supply Disposal, Labeling the Specimen, Completing Interaction (1 of 2)
Used disposable puncture devices or lancets should always be placed into a rigid, puncture-resistant biohazard container with a lid.
Contaminated supplies such as gauze, gloves, and others disposed of in other designated biohazard containers.

56. Supply Disposal, Labeling the Specimen, Completing Interaction (2 of 2)
Hand hygiene performed after contact with each patient.
Before leaving patient’s side, check puncture site to make sure bleeding has stopped; thank patient.
Adhesive bandage may be applied; bandages are not recommended for infants or young children.

57. Copyright
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58. Appendix A
Long Description for Figure 9-3 The parts of the finger include the free edge of the nail, nail bed under the finger nail, lunula at the bottom of the nail, eponychium or cuticle, the nail root where the nail grows from, the distal phalanx of the bone, and flexor tendons connected to the bone. Note the positioning of the fingertip bone, distal phalanx, and where it lies in proximity to the edge of the skin. Nails are formed like hair, from a root, and grow about 0.1 mm per day. The nail bed is tender, so punctures near the nail’s edge are more painful and not acceptable.
Return to presentation

59. Appendix B
Long Description for Figure 9-4 Photo A shows the third or fourth finger on the nondominant hand is the preferred choice. Photo B notes that the darkened areas, curved, represent the most suitable puncture sites that avoid the risk of puncturing the bone or nail bed. Keep in mind that each patient is different, and slight adjustments may be required. Photo C shows how the fingerprint grooves are often hard to see, but, if visible, the dermal puncture or incision should be across the grooves instead of parallel to the grooves. This helps form rounded drops of blood. If the incision is parallel to the grooves, blood tends to run into them and is harder to collect.
Return to presentation

60. Appendix C
Long Description for Figure 9-2 Photo A shows the Microvette Capillary Blood Collection System where a long, skinny tube collects blood from a finger. Photo B shows micro collection tubes where a tube collects blood directly from the finger.
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61. Appendix D (1 of 2) Long Description for Figure 9-14 Catalog Number
Closure Color
Additive
Mix by Inverting
Lavender
K 2 E D T A
10 times
Green
Lithium Heparin
and
Mint Green
Lithium Heparin and Gel for plasma separation
Grey
N A F L and N A 2 E D T A
and
Gold
Clot Activator and Gel for serum separation
5 times
Red
No additive
zero times

62. Appendix D (2 of 2)
Long Description for Figure 9-14 Processing of Tubes. Why. Most tubes contain an additive or clot activator that needs to be mixed with the blood sample. Tubes with anticoagulants such as E D T A need to be mixed to ensure the specimen does not clot. How. Holding tube upright, gently invert 180 degree and back. Repeat movement as prescribed for each tube. When. Immediately after drawing. Consequences if not mixed. Tubes with anticoagulants will clot. B D S S T tubes may not clot completely. Specimen will often need to be recollected.
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