5.5 Capillary & Non-Blood Collection Equipment

5.5 Capillary & Non-Blood Collection Equipment

Phlebotomy technicians collect more than venous blood. Tasks 4.06 and 4.07 test whether you can select depth-appropriate lancets, the correct microcollection tubes, and the proper non-blood containers so the laboratory receives a usable specimen on the first attempt.

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Lancet Depth Selection

Safety-engineered lancets are single-use devices with fixed or selectable puncture depths.

Never use a surgical blade or non-engineered sharp for dermal puncture. Match the device to the order (heel vs finger) and do not reuse lancets. After puncture, activate safety features and discard in a sharps container.

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Microcollection Tubes and Color Coding

Capillary blood is collected into microcollection tubes (microtainers) with color-coded additives that parallel venous tubes:

• Lavender/purple: EDTA for CBC and hematology
• Green: heparin for many chemistry plasma tests
• Gray: sodium fluoride/oxalate for glucose in some protocols
• Gold/red/SST: serum for chemistry after clotting
• Amber or light-protected: bilirubin and other light-sensitive tests

Fill to the fill line marked on the tube. Overfilling or underfilling changes additive-to-blood ratios and can cause clotting or dilution artifacts. Cap firmly and invert gently the recommended number of times. Capillary order of draw differs from venous order (blood gas → EDTA → other additives → serum); equipment selection must support that sequence when multiple micro-tubes are needed.

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Heel Warmers

Commercial heel warmers or warm moist towels increase arteriolar flow and improve specimen volume, especially for capillary blood gases and newborn collections.

Rules of safe warming:

• Target temperature about 42°C (108°F) maximum
• Apply for about 3–5 minutes
• Never use hot tap water bags of unknown temperature, microwave-heated cloths that create hot spots, or infant chemical warmers not approved by the facility
• Inspect skin after warming for redness or burn

Warming improves flow without meaningfully changing most analyte concentrations when done correctly; overheating burns the infant and may alter the specimen.

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Capillary Blood Gas Equipment

Capillary blood gas (CBG) collection uses specialized gear:

• Heparinized capillary tubes or balanced heparin devices
• Metal fleas (mixing wires) and magnets for mixing in some systems
• End caps/seals to exclude room air
• Ice slurry transport when required by laboratory policy
• Optional collection devices that minimize air bubbles

Air bubbles falsely alter pO₂ and pCO₂. Collect quickly after wiping the first drop, fill without gaps, seal both ends, mix, and label immediately. CBG is not identical to arterial blood gas but is used when arterial puncture is not appropriate.

Non-Blood Collection Containers

Urine

• Clean-catch midstream cups: routine urinalysis and many cultures when sterile technique instructions are followed
• Sterile containers: required for culture; do not substitute a nonsterile cup
• 24-hour jugs: contain preservatives for some assays—instruct patients not to discard preservative liquid
• Pediatric urine bags: for infants who cannot void on command; not ideal for culture if contamination risk is high

Swabs

Not all swabs are interchangeable.

• Dacron or rayon swabs are preferred for many microbiology and molecular tests because cotton fibers and wooden shafts can inhibit organisms or PCR reactions.
• Cotton swabs / wooden sticks may be unacceptable for certain viral, bacterial, or DNA assays.
• Use the transport medium supplied in the kit (Amies, viral transport media, etc.). Never allow a dry swab to sit when the kit requires moist transport.

Stool Kits

Stool collections may include:

• Clean wide-mouth containers for routine studies
• Vials with preservative for ova and parasite (O&P) exams
• Separate vials for culture, C. difficile, or occult blood cards Follow kit fill lines and shake preservative vials as instructed. Misusing the wrong vial is a common outpatient rejection reason.

Sputum Cups

Sterile sputum containers are used for AFB and routine respiratory cultures. Instruct patients to produce deep cough sputum, not saliva. Early morning specimens are often preferred. Leak-proof lids protect staff during transport.

Chain-of-Custody Kits (Overview)

Forensic, workplace drug screen, and some paternity collections use sealed chain-of-custody kits containing:

• Tamper-evident cups or tubes
• Security seals and custody forms
• Temperature strips (urine drug screens)
• Specimen ID labels matching the form
• Outer shipping bags

These kits are opened in front of the donor, completed without breaks in documentation, and never left unattended. Detailed custody steps are covered in the chain-of-custody procedure section; equipment competence means using the kit supplied for that legal test—not a substitute cup from the drawer.

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Equipment Selection Decision Guide

Ask four questions before every non-venous collection:

1. What specimen type was ordered (capillary blood, urine, swab, stool, sputum, forensic)?
2. What additive or transport medium does the test require?
3. What patient factors change the device (age, allergy, volume limits)?
4. What integrity features are required (sterility, light protection, custody seals)?

Choosing the correct device is as critical as choosing the correct vein. A perfectly identified patient with the wrong swab or an over-deep lancet still yields an invalid—or unsafe—collection.