When to Choose Skin Puncture Over Venous blood Collection: A Quick Guide

Skin puncture as well as the venous blood sampling are crucial techniques in the healthcare since they facilitate blood collection. It is important for those in the health care field and for patients to have a knowledge of the different procedures and techniques as well as preventive measures inherent to these procedures. This post will discuss the methods used in skin puncture and venous blood collection, the significance of hygiene and safety precautions, and ways of reducing the pain. Finally, the course will enable you to comprehend the measures that can be taken to guarantee safe blood collection.

It is critical to adhere to a uniform protocol for blood collection in order to ensure accurate and dependable results from laboratory testing. A blood sample can be taken via venipuncture or skin puncture for hematological studies.

Skin puncture blood collection

When very little blood is needed, this technique is frequently applied to newborns and young toddlers. It is appropriate for cell counts, hemoglobin estimate, hematocrit measurement using a micro method, and blood film preparation.

Another name for blood acquired through skin punctures is capillary blood. It is a combination of blood from arterioles, venules, and capillaries, though. There is also some tissue fluid in it.

Adults get their blood drawn from the lobe of their ears or the side of their middle or ring fingers (distal digits). It is collected from the big toe or heel in neonates (lateral or medial side of plantar surface).

• 70% ethanol or another appropriate disinfectant is applied to the puncture site to clean it. After drying, a sterile, dry, disposable lancet is used to make a puncture that is deep enough to permit unrestricted blood flow. Since the first drop of blood contains tissue fluid, it should be removed with sterile, dry cotton. The next few blood droplets are collected. Avoid squeezing too much as this will dilute the blood with tissue fluid. Following collection, the puncture site is covered with a piece of sterile cotton until the bleeding stops.

Hemoglobin, hematocrit, and red cell count of skin punctured blood are marginally higher than those of venous blood. The platelet count decreases as the platelets stick to the puncture site. If the result is abnormal, repeat testing cannot be done right away due to the limited sample size.

Blood should never be drawn from cold, cyanosed skin since doing so will lead to erroneous increases in hemoglobin and red/white cell counts.

Venous blood collection

An anticoagulated venous blood sample should be collected when more blood is required for several tests.

Method

• The veins in the antecubital fossa are the easiest to access for drawing blood. Applying a rubber tourniquet on the upper arm measures 18 inches by 3/4 or 1 inch for adults and 12 inches by 1/8 inch for toddlers. It shouldn’t be overly snug, and it shouldn’t stay in one spot for longer than two minutes. The patient is asked to clench their fist in order to make their veins more noticeable and tactile.
• After cleaning the puncture site with 70% ethanol, it is let to dry.
• Using the left hand, push and pull the soft tissues beneath the puncture site to anchor the chosen vein.
• For venepuncture, sterile, disposable needles and syringes should be used. Adults should wear needles with a gauge of 19 to 21, while children should use a gauge of 23.
• During venipuncture, the needle’s bevel is raised and moved in the vein’s direction. Blood is taken out gradually. Rapidly pulling the plunger may result in hemolysis and vein collapse. As soon as blood starts to flow into the syringe, the tourniquet should be loosened.
• The patient is requested to open his or her fist after the necessary amount of blood has been extracted. The needle is taken out of the vein. The puncture site is covered with sterile cotton gauze. The patient is instructed to apply pressure with the gauze until the bleeding stops.
• After removing the needle from the syringe, the necessary volume of blood is cautiously injected into the tube holding the proper anticoagulant. Hemolysis may happen if the blood is pushed through the needle without it coming loose. Glass bottles and disposable plastic tubes with flat bottoms and closures can be used as containers.
• By carefully inverting the container multiple times, blood is thoroughly mixed with the anticoagulant inside. Shaking the container vigorously can result in hemolysis and foaming, thus it is best to avoid doing so.
• Verify that the patient is feeling lightheaded and that the bleeding has stopped. Wrap the puncture location with a sticky bandage.
• Disposable needles should be properly disposed of after use by placing them in a puncture-proof container. Hand-recapping a needle might result in a needle stick injury.
• Labels are on the container. The label ought to specify the time of collecting. The correctly completed order form should be forwarded with the sample to the laboratory right away.

Precautions

• Since it will dilute the blood sample, blood is never drawn from an intravenous line or the arm that is being used for one. Blood should not be drawn from a hematoma or a sclerosed vein.
• Applying a tourniquet for more than two minutes or too tightly will result in hemoconcentration and may change the outcome of the test.
• After cleaning with alcohol, the puncture site should be left to dry completely before the venepuncture is done.
• Before taking the needle out of the vein, the tourniquet needs to be loosened (to prevent hematoma formation).
• Blood should be drawn gradually, a small-bore needle should not be used, and the needle should be removed from the syringe before drawing blood into the container in order to prevent hemolysis.
• Since all blood samples are regarded as potentially infectious, care should be taken while drawing blood by a skin puncture or vein.
• Tests should be performed on anticoagulated blood samples one to two hours after collection. If this isn’t feasible, the sample can be kept for a maximum of 24 hours at 4-6°C in a refrigerator. The sample needs to be thoroughly mixed, allowed to come back to room temperature, then analyzed once it has been removed from the refrigerator.

Complications

1. Failure to draw blood: This occurs when a vein is missed or when the plunger is pulled too hard, causing the vein to collapse.
2. Hemostasis, thrombosis, thrombophlebitis, abscess, or hemorrhage
3. Use of reusable needles and syringes that have not been adequately sterilised can result in the transmission of diseases like hepatitis B or the human immunodeficiency virus.

Consequently, such practices as skin puncture and venipuncture that are used for blood samples collection shall be considered in a bid to enhance the efficiency of the tests and the reduction of the negative effects on patients. Knowing which actions should be taken, the things that would otherwise prove to be irritating and disruptions are shunned. Every procedure should be clean and proper technique should be used at all times. Able to practice current/ competent blood collection techniques and do so safely. To get more information about procedures in the medical field, you are welcome to visit other sections of the site.