How to draw venous blood when veins are difficult to find: 5 steps to draw blood without bursting the vein

According to many clinical studies, the first-attempt needle stick failure rate can range from 10–30% depending on the patient's vascular condition and health. For the elderly, children, dehydrated individuals, or those with chronic illnesses, venipuncture can sometimes be a challenge, prolonging the testing process and causing unnecessary pain, bruising, and anxiety.

In reality, blood doesn't always flow into the tube even when the needle has entered the vein. Many cases encounter situations where venous blood cannot be drawn, blood does not enter the tube, or the blood flow is very weak, even when the procedure is performed correctly. If the cause is not correctly identified, repeated needle sticks can increase patient discomfort and affect the quality of the test sample.

In this article, Tiptory will guide you on how to recognize and handle common situations when drawing blood for tests, helping medical staff and students understand the causes of difficulties in venipuncture techniques, thereby improving the success rate from the first needle stick.

Part 1: How to adjust the needle angle when blood doesn't flow out

Step 1: Adjusting the needle during venipuncture

Gently retract the needle to adjust its position

When the needle has been inserted but no blood is flowing into the tube, slowly withdraw the needle a short distance until the bevel of the needle lies just beneath the skin's surface. This is a crucial step that allows the practitioner to safely adjust the needle's direction during venipuncture.

• Withdraw the needle slowly and with control to avoid damaging surrounding tissue.
• Keep the needle under the skin before changing the angle or direction of insertion.
• Observe the patient's reaction and the vein's position throughout the adjustment process.

Avoid completely withdrawing the needle from the skin

The needle should not be completely withdrawn from the skin when performing blood test procedure, as this can lead to several problems.

• Loss of vacuum pressure in the collection tube, making venipuncture difficult to continue.
• Increased risk of having to re-stick the needle, causing pain and discomfort to the patient.
• Can lead to subcutaneous hematoma if the needle's bevel exits the lumen or penetrates through the skin.

Make adjustments carefully

After bringing the bevel of the needle to a position just under the skin, the phlebotomist can gently adjust the needle's direction to relocate the vein lumen. Correct technique will increase the likelihood of obtaining a blood sample on the first attempt, while reducing the risk of bruising and common complications during blood test.

Step 2: How to locate the vein before drawing blood

Palpate to locate the vein

Before adjusting the needle or re-attempting venipuncture, use the index or middle finger of your non-dominant hand to palpate and accurately locate the vein's position relative to the needle tip.

• Move your fingertip gently over the area where blood will be drawn.
• Determine the direction and relative depth of the vein.
• Remember the vein's location to adjust the needle more precisely if blood hasn't flowed into the tube.

Recognizing the feel of the vein

A healthy vein usually feels soft and slightly elastic when touched.

• Veins often create a "bouncing" or slight springing sensation under the fingertip.
• When pressed and released, the vein tends to return to its original position.
• Tapping or gently palpating can help accurately locate the vein before inserting the needle.

According to medical experts, this elastic sensation is one of the important signs distinguishing veins from other subcutaneous structures.

Distinguishing veins from other tissues

When finding difficult veins, it's necessary to recognize the difference between veins and adjacent structures.

• Veins: soft, elastic, and slightly bouncy when palpated.
• Tendons or nerves: firm, hard, and less mobile.
• Subcutaneous fat tissue: soft, spongy, and easily compressible.
• Muscle: firm and harder than fat tissue.

If the vein feels abnormally hard, it could be a sclerosed or scarred vein due to repeated blood draws, infusions, or injections.

Avoid confusion with nerves

Incorrectly identifying subcutaneous structures can cause complications during blood sampling.

• Accidental nerve puncture can cause immediate, sharp pain.
• Nerve damage can lead to prolonged numbness or discomfort.
• Post-phlebotomy hematoma can compress adjacent nerves, increasing the risk of long-term damage.

Before inserting or adjusting the needle, ensure that the structure being palpated is indeed a vein. This is an important step to increase the success rate when drawing blood from difficult veins and minimize risks for the patient.

Step 3: Adjusting the needle correctly

Adjust the needle in the direction of the vein

After locating the vein, slowly change the angle or direction of the needle so that its tip aligns with the vessel lumen. This adjustment should be performed gently and with control to increase the likelihood of successfully obtaining a blood sample.

• Observe the direction of the vein before adjusting.
• Change the needle angle in small increments rather than moving it too much at once.
• Perform the maneuver slowly to limit tissue damage and reduce patient discomfort.
• Monitor blood flow into the collection tube to assess the effectiveness of the adjustment.

Prioritize small and precise movements

In cases of difficult venipuncture, needle tip adjustments should only be made with small movements.

• Slightly raise or lower the needle angle if the tip is suspected to be too shallow or too deep.
• Adjust in the direction of the vein previously identified by palpation.
• Stop immediately when blood starts to flow into the tube to avoid puncturing the vessel wall.

Do not move the needle from side to side

Absolutely avoid wiggling or pushing the needle horizontally from side to side under the skin. This is a common mistake that can increase the risk of complications during blood collection for testing.

• Causes more pain for the patient.
• Damages tissues, blood vessels, or structures under the skin.
• Enlarges the needle puncture site, causing prolonged bleeding after needle withdrawal.
• Increases the risk of bruising and hematoma at the venipuncture site.

Prioritize patient safety

When performing venipuncture techniques, the goal is not only to find the vein but also to minimize tissue damage. Small, precise, and well-directed adjustments are often much more effective than rotating or moving the needle too forcefully under the skin.

Step 4: Stabilizing the vein during blood collection

Keep the vein stable before inserting the needle

One common reason venipuncture is difficult is that the vein moves or "rolls" out of position when the needle approaches. Therefore, proper vein stabilization is a crucial step to increase the success rate of blood collection.

• Place the thumb of your non-dominant hand below the venipuncture site.
• Gently pull the skin and subcutaneous tissue downward to create tension.
• Keep the skin adequately taut throughout the process of inserting the needle into the vessel lumen.
• Maintain a stable anchoring force until blood flows into the collection tube.

Create skin tension to prevent the vein from rolling

When the skin is held taut, the vein will move less under the action of the needle tip.

• Helps the needle tip accurately access the intended puncture site.
• Reduces the phenomenon of the vein being pushed aside instead of being punctured.
• Increases the likelihood of obtaining a blood sample on the first attempt.
• Reduces the number of times adjustments or re-sticks are necessary.

Notes on blood collection in the elderly

Elderly individuals often have thinner skin and more mobile veins compared to younger people.

• Skin is easily damaged if pulled too forcefully.
• Veins tend to roll or slide away from the needle tip.
• Veins need to be stabilized with gentle but firm pressure.
• Avoid excessive force as it can cause pain or bruising after blood collection.

In many cases, the needle tip does not enter the vessel lumen because the vein has been displaced to the side upon contact. Good stabilization helps prevent this situation.

Caution with special stabilization techniques

Some medical staff use a technique of pulling the skin taut in two directions simultaneously to increase the ability to stabilize the vein. However, this method can increase the risk of needlestick injury if the patient suddenly jerks their hand or shows a withdrawal reflex when experiencing pain.

• Always prioritize safety during blood sampling.
• Maintain a safe distance between fingers and the needle tip.
• Anticipate potential reactions in anxious patients or those with needle phobia.
• Prioritize simple, effective, and controllable stabilization techniques.

Good stabilization helps increase the success rate of blood collection

In the practice of venipuncture technique, keeping the vein stable is often as important as accurately locating the blood vessel. A gentle yet firm stabilization maneuver helps prevent the vein from rolling, reduces patient pain, and improves the quality of the test sample.

Step 5: Re-insert the needle and collect the blood sample

Continue to advance the needle into the vein slowly

After correctly identifying the vein's direction and securely stabilizing the blood vessel, gently advance the needle deeper into the skin. During this process, carefully observe for signs of blood appearing in the needle hub or flowing into the collection tube.

• Advance the needle incrementally, avoiding overly rapid maneuvers.
• Continuously monitor whether blood has started to flow.
• Maintain the fixed position of the vein to prevent it from rolling.
• Do not abruptly change the needle's direction while advancing it.

Observe the patient's reaction

Patient safety and comfort should always be prioritized during venipuncture.

• Ask the patient about the level of pain or discomfort.
• Immediately stop the procedure if severe or unusual pain occurs.
• Re-evaluate the needle position if the patient experiences radiating pain, numbness, or prolonged tingling.
• Reassure the patient to reduce stress during blood collection.

Collect blood samples according to the correct order of tubes

Once a stable blood flow is established, proceed to collect samples in the correct order of collection tubes according to professional regulations.

• Keep the needle and vein stable throughout the sampling process.
• Minimize needle movement when changing tubes.
• Ensure each tube receives the required blood volume for testing.
• Adhere strictly to the procedure to avoid affecting test results.

Invert the tubes after blood collection

Even in cases of difficult blood collection, proper tube inversion is crucial to ensure the quality of the specimen.

• Gently invert and rotate the tube the number of times recommended by the manufacturer.
• Do not shake vigorously, as this can cause hemolysis.
• Perform inversion immediately after sample collection.

Specifically, tubes containing anticoagulants such as EDTA tubes (purple cap) or Heparin tubes (green cap) need to be inverted correctly to ensure even distribution of the anticoagulant throughout the blood sample.

Prevent blood clots from affecting test results

If whole blood samples show small clots, the laboratory may not be able to analyze them, or the results may be inaccurate.

• Proper inversion helps prevent micro-clot formation.
• Ensures sample quality for hematology and biochemistry tests.
• Reduces the risk of having to redraw blood, saving time for both patients and medical staff.

Establishing blood flow is only one part of the venipuncture technique. Collecting samples in the correct order and handling tubes properly ensures accurate and reliable test results.

Part 2: How to handle common blood collection errors

Step 1: Checking the collection tube when blood flow is weak

Check the quality of the collection tube

If the needle has been inserted correctly but blood still doesn't flow or flows very slowly, the cause may not be the vein but the blood collection tube itself.

• Check the expiration date of the tube.
• Do not use expired or damaged tubes.
• Replace immediately if the tube has been dropped or severely impacted.
• Ensure the tube still has sufficient vacuum pressure to draw blood effectively.

In venipuncture practice, a compromised vacuum in the collection tube is a common reason why blood doesn't flow into the tube even when the needle is correctly positioned within the vessel lumen.

Ensure the tube is correctly seated

Before readjusting the needle, check if the collection tube is correctly attached to the holder.

• Ensure the tube is pushed correctly into the holder.
• Check if the inner needle has penetrated the rubber stopper of the tube.
• Observe if blood starts to flow after adjusting the tube's position.
• Replace with a new tube if the current tube is suspected to be faulty.

Sometimes, simply re-seating the tube correctly can restore blood flow without needing to re-stick the needle.

Keep the needle stable when changing collection tubes

When changing collection tubes during blood sampling for testing, it is essential to keep the needle tip very stable to avoid dislodging it from the vein.

• Maintain a steady grip with your non-dominant hand.
• Avoid shaking or rotating the needle when attaching or detaching tubes.
• Continuously observe blood flow after replacing with a new tube.
• Avoid abrupt movements that could cause the needle to lose its position within the vessel lumen.

Handling incorrect tube order

In some cases, the phlebotomist might accidentally use the wrong order of tubes according to the standard procedure.

• Remove the currently used tube from the holder.
• Attach the correct type of tube needed in the prescribed order.
• Collect about half the required blood volume into this tube and then discard it.
• Then use a new tube of the same type and collect the necessary sample volume.

This handling method helps reduce the risk of interference from residual additives at the needle tip or in the collection system.

Minimize cross-contamination of additives between tubes

Each type of test tube may contain different additives, such as anticoagulants or clot activators. If collected in the wrong order, these substances can contaminate subsequent samples and lead to inaccurate results.

• Adhere strictly to the blood collection order specified by the laboratory.
• Carefully check the tube type before starting sample collection.
• Provide regular training and practice to reduce errors during venipuncture technique.

When experiencing weak or no blood flow into the collection tube, do not immediately adjust the needle. Checking the collection tube and the collection system is often a simple step that can quickly and effectively resolve the issue.

Step 2: Addressing incorrect needle placement during blood collection

Needle not yet in the vein

If the needle tip remains in the skin or subcutaneous tissue without penetrating the vein lumen, blood will not flow into the collection tube. This is a common situation during venipuncture in overweight individuals or those with a thick layer of subcutaneous fat.

• No blood appears in the needle hub or collection tube.
• The puncture site may be correct, but the needle depth is insufficient.
• Slowly advance the needle a short distance further in the direction of the vein.
• Continuously observe for signs of blood appearing during adjustment.

Needle has gone through the vein

This situation occurs when the needle tip passes through the posterior wall of the vein. The practitioner may see a small flash of blood appear in the needle hub, but then the blood flow is not sustained.

• Often occurs when inserting the needle too quickly or too deeply.
• An excessively large needle insertion angle also increases the risk of puncturing the vessel wall.
• Can cause hematoma due to blood escaping into surrounding tissue.
• Secure the vein firmly, then slowly withdraw the needle little by little until blood flows steadily.

Needle only partially in the vein lumen

If the needle tip has only touched or partially entered the vessel lumen, blood flow is usually very weak or intermittent.

• Blood enters the tube abnormally slowly.
• Insufficient blood volume collected for testing.
• Keep the vein still and gently advance the needle further.
• Avoid inserting the needle too deeply, which could cause the tip to puncture the posterior wall of the vessel.

Needle pressed against the vein wall

The needle tip may be inside the vessel lumen but pressed against the vein wall, obstructing blood flow into the tube.

• Blood flows slowly or stops abruptly.
• Common in veins with curves or bifurcations.
• Withdraw the needle slightly to free the tip from the vessel wall.
• In some cases, gently rotate the needle assembly about a quarter turn to improve blood flow.

Needle touching a venous valve

Veins have valves that help blood flow in one direction. If the needle tip touches a valve, blood flow can be significantly obstructed.

• Blood flow is weak or unstable.
• A slight tremor or a feeling like the needle tip is "shaking" can be felt as the valve opens and closes.
• This condition often occurs in areas of veins with many bends.
• Gently withdraw the needle a short distance to avoid contact with the valve.

Needle located beside the vein

This occurs when the needle tip passes alongside the vein instead of penetrating the lumen, often referred to as a "rolling" or "slipping" vein.

• No blood is collected, even though the puncture site appears correct.
• Often happens when the vein is not sufficiently stabilized before needle insertion.
• The vein is pushed aside by the needle tip.
• The vein must be held very steadily, and the needle direction adjusted appropriately to re-access the vessel lumen.

Correctly identifying the cause helps reduce multiple repunctures

In venipuncture technique practice, accurately determining the needle tip's position is crucial for success. When blood does not flow into the tube, instead of withdrawing the needle and repuncturing immediately, assess the physical signs to determine the needle's location. This helps reduce patient pain, minimize hematoma, and improve the quality of the blood sample.

Step 3: Recognizing a collapsed vein

Signs of a collapsed vein during blood collection

A collapsed vein is a common cause of sudden cessation of blood flow during venipuncture. When this occurs, the vein walls constrict and press against each other, obstructing or completely blocking blood flow into the tube.

• Blood was flowing normally, then suddenly stopped.
• No signs of needle displacement are detected.
• Changing the tube still yields very little or no blood.
• Often seen in individuals with small, fragile, or difficult-to-access veins.

Causes of vein collapse

Many factors during blood collection can cause the vein wall to constrict.

• Excessive vacuum pressure from the tube compared to the vein size.
• Tourniquet tied too tightly.
• Tourniquet placed too close to the venipuncture site.
• Tourniquet removed too early, causing a sudden drop in venous pressure.
• Dehydrated patients or those with small, fragile veins.

How to manage suspected vein collapse

When blood flow stops, but the needle tip appears to be in the correct position, consider the possibility of a collapsed vein before adjusting the needle.

1. Recheck the position and tension of the tourniquet.
2. Ensure the tourniquet is not too loose or too tight.
3. Observe if blood flow resumes after adjusting the pressure.
4. Avoid excessive needle movement, as this can damage the vessel wall.

Increase venous pressure if using a butterfly needle

When performing difficult venipuncture with a butterfly needle, adjusting the tourniquet can help restore blood flow.

• Retie the tourniquet correctly on the patient's arm.
• Increase venous pressure moderately.
• Observe if blood flows back into the tube.
• Avoid constricting too tightly, which can cause patient discomfort or affect circulation.

Change tube type when necessary

If the tube's vacuum is suspected to be the cause of vein collapse, measures to reduce vacuum pressure can be applied.

• Remove the current tube from the collection system.
• Wait a few seconds for the vein to regain its original shape.
• Use a tube with lower vacuum or a small-volume collection tube.
• Continue to monitor blood flow after attaching the new tube.

Assess before repuncturing

Not all cases of stopped blood flow are due to the needle being dislodged from the vein. Correctly identifying a collapsed vein helps avoid unnecessary repunctures, reduces patient pain, and improves the effectiveness of venipuncture technique. In many cases, simply adjusting the pressure or changing the tube can restore blood flow without needing to repeat the procedure.

Part 3: Tips for quickly and accurately finding veins for difficult cases

Tip 1: Adjusting posture during blood collection

Positioning the arm correctly before blood collection

The patient's posture directly affects the ability to locate and access a vein. In many cases of difficult venipuncture, proper posture adjustment can help make veins more prominent without changing the puncture site.

• Completely extend the arm when collecting blood from the antecubital fossa.
• Avoid bending or slightly flexing the elbow.
• Keep the arm relaxed to prevent muscle tension.
• Maintain a stable posture throughout the blood collection process.

Keep the arm level with or below the heart

Arm position affects the amount of blood pooled in the veins.

• Position the arm at heart level or slightly lower.
• Avoid raising the arm above the heart.
• When the arm is in the correct position, veins are usually fuller and more visible.
• Supports improved blood flow during venipuncture.

In many cases, lowering the arm below heart level can make veins more engorged, increasing the chances of successful blood collection.

Using pillows or cushions for support

Simple support tools can help the patient maintain a more comfortable and stable posture.

• Place a small pillow or foam cushion under the arm.
• Helps maintain the extended position of the elbow.
• Reduces fatigue for the patient when holding their arm for an extended period.
• Makes it easier for the practitioner to locate the vein.

Adjusting to a suitable sitting posture

When the patient is seated in a specialized phlebotomy chair, their sitting posture also needs attention.

• Sit upright with the back against the chair.
• Keep shoulders relaxed, avoiding stiffness.
• Adjust chair height to suit the practitioner.
• Ensure the vein's position is within easy view and reach for manipulation.

Proper posture arrangement helps reduce pressure on the healthcare professional's wrists, shoulders, and back, while also increasing accuracy during the procedure.

Rotating the arm to better visualize veins

If veins are difficult to locate in the current position, try gently rotating the patient's arm.

• Rotate the palm upwards or slightly outwards.
• Adjust the rotation angle incrementally to observe changes in the veins.
• Can help reveal veins located on either side of the forearm more clearly.
• Useful in cases of difficult vein finding for blood collection.

Correct posture increases successful blood collection rates

Before changing the needle or repuncturing, assess the patient's posture. An arm that is extended, positioned below the heart, and well-supported usually makes veins more prominent, reduces the risk of missed punctures, and improves the effectiveness of venipuncture technique from the first attempt.

Tip 2: Using a tourniquet correctly

Placing the tourniquet in the correct position

The tourniquet is an important tool to make veins more prominent during venipuncture. However, if not placed correctly, finding and accessing the vein can become more challenging.

• Place the tourniquet approximately 3-4 finger widths above the intended puncture site.
• Ensure the tourniquet is above the collection area and does not obscure the vein to be observed.
• Recheck vein prominence after applying the tourniquet.
• Adjust the position if the vein is not clear or the patient feels uncomfortable.

Adjusting tightness sufficiently

The purpose of the tourniquet is to engorge and make veins more prominent, making blood collection easier and more accurate.

• Tie it tight enough for the veins to fill with blood and be easily palpable.
• Do not tie too loosely, as the veins will not become prominent.
• Do not tie too tightly, as this can obstruct arterial circulation.
• Observe skin color and patient sensation after applying the tourniquet.

When used correctly, the tourniquet will help veins become engorged, firm, and easier to access during needle insertion.

Recognizing signs of an overly tight tourniquet

An overly tight tourniquet does not improve blood collection effectiveness and can cause various problems in venipuncture technique practice.

• Patient feels significant pain or numbness in the arm.
• Skin below the tourniquet becomes abnormally reddish-purple.
• Veins may be excessively compressed.
• Blood flow into the tube is slow or stops completely.

If an overly tight tourniquet is suspected, loosen or re-tie it before adjusting the needle.

Considerations when collecting blood from elderly patients

Elderly individuals often have thinner vessel walls and more fragile veins compared to younger people.

• Avoid constricting the tourniquet too tightly.
• Monitor the vein's response after applying the tourniquet.
• Prioritize gentle pressure that is still sufficient to make the vein prominent.
• Limit maneuvers that exert excessive pressure on the blood vessels.

In some cases, an overly tight tourniquet can cause the vein to collapse immediately upon needle insertion, making difficult venipuncture even harder instead of easier.

Check the tourniquet before adjusting the needle

When blood does not flow or flows very slowly, do not immediately assume the needle is in the wrong position. Check the tourniquet first.

• Assess the tourniquet's placement.
• Check the tourniquet's tension.
• Observe the vein's prominence.
• Adjust if necessary before changing the needle position.

A tourniquet placed correctly and with appropriate tightness will increase the likelihood of successful blood collection, reduce the number of needle sticks, and improve the quality of the test sample.

Tip 3: Assessing the blood collection site

Thoroughly examine the proposed blood collection area

Before performing venipuncture, a comprehensive assessment of the puncture site is necessary to select the most suitable vein. A detailed examination helps increase the success rate of blood collection and reduces the risk of multiple punctures.

• Prioritize veins in the antecubital fossa.
• Assess the prominence, elasticity, and ability of the vein to be stabilized.
• Observe skin color and any abnormal signs around the blood collection area.
• Avoid choosing sites with lesions or signs of inflammation.

Prioritizing common blood collection sites

In venipuncture technique practice, the antecubital fossa is usually the first choice due to the large size and easy accessibility of its veins.

1. The median cubital vein is often the preferred choice.
2. The cephalic vein is the next option if the median cubital vein is not suitable.
3. The basilic vein can be considered when other sites are difficult to access.

If a suitable vein cannot be found on one arm, assess the other arm before moving to other sites.

Observing signs from previous blood collections

Previous needle sticks can significantly affect vein quality.

• Look for areas of purple or yellow bruising.
• Observe signs of hematoma from recent blood draws or IV infusions.
• Avoid puncturing areas with existing bruising or injury.
• Assess the accessibility of veins around previously used sites.

These signs can indicate that the site has been recently used and may pose difficulties for the next blood collection.

Paying attention to scar tissue on veins

Each time a needle penetrates a vein, the body forms scar tissue to repair the injury. When blood collection or IV infusions occur frequently, scar tissue can accumulate over time.

• Veins become harder to the touch.
• Vessel walls are less elastic.
• The needle tip is harder to penetrate than with normal veins.
• Increases the risk of encountering difficult venipuncture.

This is why many patients who require regular blood tests often have more difficult-to-access venous systems.

Looking for visual signs of veins

Visual observation can provide much useful information before palpating for a vein.

• Blue lines under the skin often indicate prominent veins.
• A clearly visible vein is not necessarily the best choice, but it is a useful starting point for examination.
• Combine visual observation with palpation for a more accurate assessment.
• Do not rely solely on external appearance while disregarding the tactile sensation of the vein.

Approaching vein finding systematically

A systematic search procedure helps reduce overlooking suitable blood collection sites.

1. Start with the arm closest to the practitioner.
2. Examine the antecubital fossa first.
3. Prioritize finding the median cubital vein.
4. Continue to assess the cephalic and basilic veins.
5. Move to the opposite arm if a suitable site has not been found.
6. Only consider the back of the hand when preferred sites are not feasible.

Leveraging patient experience

Patients who frequently have blood tests often know their venous system very well.

• Ask the patient about successful blood collection sites in previous instances.
• Note sites that are often difficult to draw blood from or cause pain.
• Refer to information about veins that have been effectively used before.
• Combine patient experience with professional assessment to select the optimal site.

In many cases, the patient is a useful source of information that can shorten the time taken to find a vein and improve the effectiveness of blood collection.

Tip 4: Applying warmth to make veins prominent

Using heat to aid vein finding

When facing difficult venipuncture, especially in individuals with small or hard-to-see veins, applying warmth is a simple but effective measure to increase the visibility and palpability of veins.

• Warm temperatures help blood vessels dilate naturally.
• Increases blood flow to the collection area.
• Makes veins more prominent and easier to access.
• Helps reduce unnecessary needle sticks.

How to apply warmth correctly

Before proceeding with blood collection, heat can be applied to the proposed collection site to improve vein access.

1. Place a warm pack or heating device on the area where blood is to be collected.
2. Maintain a comfortable temperature, not too hot.
3. Apply warmth continuously for about 5 minutes.
4. Then reassess the vein's prominence and elasticity.

Applying warmth for a sufficient duration allows blood vessels to maximally dilate before the procedure.

Choosing appropriate heating devices

Many healthcare facilities use specialized warming devices to assist in finding veins.

• Warming pads used for capillary blood collection in neonates.
• Clean warm towels heated to a safe temperature.
• Gloves filled with warm water or specialized warm water bags.
• Warming devices as prescribed by the healthcare facility.

Regardless of the method used, temperature must always be controlled to avoid burns or skin irritation.

Re-evaluate the vein after warming

After warming the blood collection area, re-examine it before venipuncture.

• Observe whether the vein is more prominent.
• Palpate to assess the vein's elasticity.
• Check the blood vessel's ability to remain fixed under the skin.
• Re-select the optimal site if a more suitable vein appears.

In many cases, a previously hard-to-find vein can become significantly more visible and palpable after a few minutes of warming.

Useful measures for difficult blood draws

Warming is particularly useful for patient groups who often have difficulty finding a vein for blood collection.

• Elderly individuals with small and fragile veins.
• Dehydrated individuals.
• Individuals with poor peripheral circulation.
• Patients requiring frequent blood tests.
• Individuals with deep veins under subcutaneous fat.

Before deciding to change the blood collection site or re-stick multiple times, consider warming. This is one of the simple, safe, and effective measures that can significantly improve the success rate of venipuncture techniques.

Tip 5: Choose the right blood collection needle

Needle selection based on vein condition

Choosing the correct needle type greatly impacts the success rate of venipuncture. There isn't one needle type suitable for all cases, as each patient has different vein characteristics and testing needs.

• Assess the size and elasticity of the vein.
• Consider the number of tubes to be collected.
• Estimate the difficulty of the blood draw.
• Select instruments based on experience and actual clinical assessment.

A suitable choice from the outset can help reduce the number of needle sticks and improve sample quality.

21G needle for routine blood draws

The 21G needle is commonly used in most routine blood tests.

• Larger needle diameter ensures stable blood flow.
• Suitable for medium to large veins.
• Supports collecting multiple tubes in one blood draw.
• Reduces the risk of hemolysis due to better blood flow.

This is usually the preferred choice when veins are easily accessible and there are no complicating factors.

23G needle suitable for small veins

In cases of small or fragile veins, a smaller gauge needle may be a more suitable choice.

• Smaller diameter helps reduce pressure on the vessel wall.
• Suitable for elderly individuals or those with thin veins.
• Helps access difficult-to-draw veins.
• Reduces the risk of damaging blood vessels during venipuncture.

However, blood flow may be slower compared to using a larger gauge needle.

Advantages of butterfly needles in difficult blood draws

The butterfly needle is one of the most useful tools when dealing with difficult venipuncture cases.

• Easier to control the needle tip during manipulation.
• Shorter needle length increases accuracy.
• Suitable for small, superficial, or rolling veins.
• Allows for venipuncture at a shallow angle, typically around 10–15 degrees.
• Helps reduce the risk of puncturing the posterior wall of the vein.

Due to its flexible control, the butterfly needle is often preferred for blood collection in children, the elderly, or patients with difficult-to-access venous systems.

Notes on using butterfly needles

When performing certain special tests, the use of a butterfly needle requires adherence to specific sample collection procedures.

• If a sodium citrate tube is the first tube in the draw order, a discard tube must be used first.
• The purpose is to remove any remaining air in the tubing of the butterfly needle set.
• After the discard tube has been sufficiently filled, the official test sample can be collected.
• This ensures that the blood-to-additive ratio in the test tube meets standards.

Choosing the right needle improves blood collection efficiency

In the practice of venipuncture technique, a larger needle is not always better, nor is a smaller needle always safer. The choice should be based on the characteristics of the vein, the purpose of the test, and the difficulty of each patient case. A suitable needle will help reduce patient pain, minimize complications, and improve the quality of the blood sample collected.

Tip 6: Use small volume collection tubes

Consider using small volume collection tubes

In cases of difficult venipuncture, especially when veins are small or prone to collapse, small volume collection tubes can be an effective solution to improve the ability to collect blood samples.

• Have a lower blood capacity compared to standard collection tubes.
• Create a gentler vacuum during blood collection.
• Reduce pressure on the vein wall.
• Limit the risk of vein collapse when blood is drawn into the tube.

This option is often considered when collecting blood from fragile or easily damaged veins.

Effective support for the elderly and children

The veins of the elderly and young children are often smaller and more susceptible to the vacuum pressure of the collection tube.

• Reduces the risk of blood flow interruption mid-draw.
• Limits vein collapse during sample collection.
• Helps ensure a more stable blood collection process.
• Increases the likelihood of collecting the required blood volume on the first attempt.

For these patient groups, choosing the right type of collection tube can sometimes be as important as selecting the appropriate blood collection needle.

Suitable for blood collection from dorsal hand veins

The veins on the back of the hand are often smaller and more susceptible to damage than antecubital veins.

• Low vacuum pressure helps protect the vessel wall.
• Reduces the risk of hematoma or vessel collapse.
• Helps maintain stable blood flow throughout the sample collection process.
• Increases efficiency when performing venipuncture techniques at difficult sites.

For this reason, small volume collection tubes are often used when collecting blood from the hand or other small peripheral veins.

Identifying small volume collection tubes

Some manufacturers design specific identifiers for small volume collection tubes.

• Rubber stoppers may have a different color or transparency than the standard version.
• May have a specific symbol on the product label.
• The collection volume is clearly marked on the tube body.
• It is necessary to carefully check product information before use.

Correct identification of the tube type helps avoid confusion during sample collection and ensures adherence to testing procedures.

Still, the correct blood volume must be collected to the specified line

Even with small volume collection tubes, some tests still require a precise blood volume to ensure reliable results.

• EDTA tubes must be filled to the specified line.
• Sodium citrate tubes must also be filled to the correct marked level.
• Insufficient sample collection should be avoided as it can alter the blood-to-additive ratio.
• An inaccurate ratio can directly affect test results.

Improving sample quality in difficult blood draws

When encountering small, collapsible veins or difficulty maintaining blood flow, switching to small volume collection tubes is a worthwhile consideration. This measure helps reduce suction pressure on blood vessels, limits complications, and improves the effectiveness of venipuncture, especially in children, the elderly, and cases with difficult-to-access venous systems.

Important notes when performing difficult blood draws

Keep the needle stable when changing tubes

In some cases, blood flows well into the first tube but stops when switching to the next. The cause is often that the needle tip has shifted out of its position within the vein lumen.

• Hold the tube holder firmly when changing tubes.
• Avoid accidentally pushing the needle deeper into the blood vessel.
• Limit shaking or rotating the needle during manipulation.
• After establishing stable blood flow, adjust hand position to better stabilize the needle.

Keeping the needle stable helps maintain continuous blood flow and reduces the risk of needing to re-stick.

Adjust needle angle correctly

The angle of needle insertion into the skin directly affects the ability to access the vein.

• Typically, the needle is inserted at an angle of approximately 30–45 degrees.
• With a butterfly needle, the insertion angle is usually shallower.
• When blood appears in the needle hub, lower the needle angle closer to the skin.
• Advance the needle a very short distance further so that the tip is stably positioned within the vessel lumen.

This technique helps reduce the risk of puncturing the posterior wall of the vein and maintains more stable blood flow during venipuncture.

Adjust approach for uncooperative patients

Some patient groups may move suddenly during blood collection, increasing the risk of failure or occupational accidents.

• Children are often anxious and react strongly to needles.
• Individuals with neurodevelopmental disorders or mental health conditions may find it difficult to keep their arm still.
• Additional assistance should be provided to stabilize the arm when necessary.
• Butterfly needles often provide better control in these situations.

Patient and healthcare worker safety must always be prioritized.

Considerations for hypovolemic patients

Patients with severe chronic illness or who have recently experienced major trauma may have reduced circulating blood volume (hypovolemia).

• Veins are smaller and harder to visualize.
• Blood flow is slow during sample collection.
• It is difficult to find a suitable blood collection site.
• Consult with experienced colleagues or the responsible nurse when encountering difficulties.

This group of patients often experiences difficult venipuncture and requires careful assessment before the procedure.

Limit the number of needle sticks

Repeated needle sticks not only cause pain but also increase the risk of complications.

• No more than two consecutive needle sticks should be attempted by the same person if a sample has not been obtained.
• If still unsuccessful after several attempts, seek assistance from more experienced personnel.
• Avoid continuing if the likelihood of success is low.
• Always adhere to the healthcare facility's professional protocols.

Avoid excessive vein probing

"Probing" for a vein under the skin by continuously moving the needle tip is a common mistake in venipuncture technique.

• Causes significant pain to the patient.
• Increases the risk of hitting nerves, tendons, or arteries.
• Increases the risk of hematoma and tissue damage.
• Only adjust the needle when the relative position of the vein has been clearly identified.

If unsure about the needle tip's position, withdrawing and re-evaluating is often safer.

Caution with special blood collection sites

Some blood collection sites require specific medical indications or professional guidance.

• Do not arbitrarily draw blood from IV lines without permission.
• Thoroughly assess factors that could affect test results.
• Do not draw blood from an arm with an arteriovenous fistula used for hemodialysis.
• Fully comply with healthcare facility regulations for special cases.

Stop the procedure immediately if danger signs appear

The blood collection process should be stopped immediately if any of the following abnormal signs appear:

1. Bright red blood pulsing, suggesting accidental arterial puncture.
2. The patient feels an electric shock-like pain radiating down the arm or hand.
3. A rapidly growing swelling appears under the skin at the blood collection site, suspected hematoma.
4. The patient faints or experiences seizures.
5. The patient requests to stop the procedure.

In these situations, the needle should be withdrawn immediately, the situation handled according to professional protocol, and reported to the responsible healthcare personnel.

Prioritize safety over speed

The goal of venipuncture is not only to obtain a blood sample but also to ensure the patient's safety and comfort. Correctly assessing the situation, knowing when to proceed and when to stop, is crucial for improving professional quality and limiting complications.

References

1. Clinical and Laboratory Standards Institute. (2017). Collection of Diagnostic Venous Blood Specimens (7th ed., CLSI Standard GP41). Wayne, PA: Clinical and Laboratory Standards Institute.
2. World Health Organization. (2010). WHO Guidelines on Drawing Blood: Best Practices in Phlebotomy. Geneva, Switzerland: World Health Organization.
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4. Garza, D., & Becan-McBride, K. (2022). Phlebotomy Handbook: Blood Collection Essentials (11th ed.). Hoboken, NJ: Pearson Education.
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9. Cornes, M. P., Church, S., van Dongen-Lases, E., Grankvist, K., Guimarães, J. T., Ibarz, M., Kristensen, G. B. B., Lippi, G., Simundic, A. M., & Nybo, M. (2016). Standardization of venous blood collection procedures. Clinical Chemistry and Laboratory Medicine, 54(1), 27–39.
10. Simundic, A. M., Church, S., Cornes, M. P., Grankvist, K., Lippi, G., Nybo, M., Kovalevskaya, S., Sprongl, L., Sumarac, Z., & Working Group for Preanalytical Phase. (2018). Standardization of collection requirements for fasting samples. Clinical Chimica Acta, 483, 74–79.
11. Infusion Nurses Society. (2024). Infusion Therapy Standards of Practice. Journal of Infusion Nursing, 47(1S), S1–S285.
12. Bain, B. J., Bates, I., Laffan, M. A., & Lewis, S. M. (2021). Dacie and Lewis Practical Haematology (13th ed.). Philadelphia, PA: Elsevier.
13. Rodak, B. F., Carr, J. H., & Doig, K. (2020). Hematology: Clinical Principles and Applications (6th ed.). St. Louis, MO: Elsevier.
14. Pagana, K. D., Pagana, T. J., & Pagana, T. N. (2022). Mosby's Diagnostic and Laboratory Test Reference (16th ed.). St. Louis, MO: Elsevier.
15. Becton, Dickinson and Company. (2023). BD Vacutainer Specimen Collection Guidelines and Best Practices. Franklin Lakes, NJ: Becton, Dickinson and Company.

Content edited by: Rowan Hudson Le.

Information consulted and verified by expert: Andrew Collins.