A lancet is a small, sharp instrument designed to puncture the skin and obtain a tiny blood sample. These devices are most commonly used for point-of-care testing, such as monitoring blood glucose levels in people with diabetes. The process requires piercing the capillary bed beneath the skin surface to collect a small droplet for immediate analysis. Understanding the correct technique ensures the sample is sufficient and minimizes discomfort. Proper use involves selecting the right tools, preparing the sampling site, and following strict safety guidelines for disposal.
Selecting the Device and Preparing the Site
The lancet is the sterile, disposable needle component used for the puncture. This needle is housed within a lancing device, a spring-loaded mechanism that controls the speed and depth of the puncture. Users must load a new, sterile lancet into the device according to the manufacturer’s directions, ensuring the protective cap is removed only when ready.
Selecting the optimal puncture site helps reduce pain and tissue damage over time. The sides of the fingertips are generally preferred because they have fewer nerve endings than the sensitive pads. It is beneficial to rotate between different fingers and sites for each test to allow previous puncture sites adequate time to heal completely.
The lancing device usually features an adjustable dial or cap to set the penetration depth. Individuals with thinner skin may require a lower depth setting, while those with thicker or calloused skin might need a deeper setting to reach the capillaries. Adjusting the depth to the minimum effective setting is important for reducing pain and preventing unnecessary deep tissue injury.
Preparing the skin before the puncture prevents the introduction of microorganisms into the sample or the body. The chosen site should be washed thoroughly with warm soap and water, then dried completely before proceeding. If an alcohol swab is used, wait until the alcohol has completely evaporated from the skin surface. Residual alcohol can contaminate the blood sample and cause a stinging sensation.
Performing the Blood Sample Collection
Once the site is clean and the depth is set, the lancing device should be pressed firmly against the prepared skin. Applying firm pressure temporarily increases blood flow and ensures the lancet penetrates to the desired depth. The device is then activated by pressing the release button, which quickly inserts and retracts the lancet in one smooth, rapid motion.
A quick and decisive puncture helps minimize the sensation of pain, as the nerves have less time to register the injury. After the puncture, the first tiny droplet of blood that appears should be wiped away with a clean, dry tissue. This initial drop may contain excess tissue fluid or residual contaminants from the skin, which could affect the accuracy of the test result.
The second drop of blood is the one used for testing and should be encouraged to form naturally. This is best achieved by gently “milking” the finger from the base towards the puncture site without squeezing directly around the wound. Squeezing the immediate puncture area can cause tissue fluid to mix with the blood, leading to a sample that is diluted and possibly inaccurate for testing.
The required blood volume is quite small, often just a microliter, and is readily absorbed by the test strip or collection medium. The strip’s absorbent tip should be lightly touched to the top of the blood drop, allowing it to draw the sample in by capillary action. It is important not to smear the blood onto the strip, as this can interfere with the chemical reaction necessary for an accurate reading.
Safe Handling and Sharps Disposal
After obtaining the sample, apply light pressure to the puncture site using a clean piece of gauze or cotton ball to stop any residual bleeding. This pressure encourages rapid clot formation and protects the small wound from contamination.
Used lancets must be handled carefully to prevent accidental needle-sticks, which pose a risk of infection or disease transmission. The used lancet should be carefully removed from the lancing device, often by using the device’s protective cap to safely cover the sharp tip before extraction. Never attempt to recap the needle by hand, which is a common cause of accidental injury.
The disposal of the sharp instrument requires using a designated, puncture-proof sharps container. These containers are designed to safely contain needles and prevent injury to sanitation workers or others. Under no circumstances should used lancets or other sharps be placed directly into regular household trash, recycling bins, or flushed down the toilet.