Blood Cultures, Nonblood Specimens, CLIA-Waived QC & Equipment Verification

Blood Culture Collection — Aseptic Technique

Blood cultures detect bloodstream infections such as bacteremia or sepsis, so sterility is the top priority — any skin bacteria introduced into the bottle becomes a false-positive contaminant that can trigger unnecessary antibiotics.

1. Select the venipuncture site, with the median cubital vein preferred, and apply the tourniquet.
2. Scrub the site with chlorhexidine gluconate, or 70% isopropyl alcohol followed by iodine/povidone if the patient has a chlorhexidine allergy or is under two months old, using a friction scrub that works outward from the center.
3. Allow the antiseptic to fully air dry, which typically takes about 30 seconds for chlorhexidine — wiping it away or touching the site again after prep breaks sterility and requires re-cleaning.
4. Do not re-palpate the cleaned site with an ungloved finger; if repalpation is necessary, use a sterile gloved finger or re-clean the site.
5. Clean the bottle tops with alcohol before inoculating them.
6. Draw the aerobic bottle first, then the anaerobic bottle, per most facility protocols, filling each bottle to its indicated volume — underfilling reduces the sensitivity for detecting organisms.
7. Label each bottle at the bedside with the collection site, time, and the collector's initials.

Two blood culture sets from different sites are often ordered to help distinguish a true bloodstream infection from a skin-contaminant result.

Nonblood Specimen Collection

CPCT/A-level phlebotomists and patient care technicians also collect, or instruct patients on collecting, nonblood specimens:

• Urine, clean-catch midstream — instruct the patient to cleanse the urethral area front-to-back (women) or clean the glans (men), begin urinating into the toilet, then catch a midstream sample in the sterile container without touching the inside of the cup, and finish voiding into the toilet. This technique minimizes contamination from skin flora.
• Stool specimens — collected in a clean, dry container without contamination from urine or toilet water, used for occult blood, ova and parasite exams, or culture. Gloves are required for handling.
• Sputum specimens — best collected as a deep-cough sample first thing in the morning, when secretions have pooled overnight, after rinsing the mouth with water, not mouthwash, which can affect culture results.

All nonblood specimens require the same two-identifier patient identification and bedside labeling standards used for blood specimens.

CLIA-Waived Quality Control

Point-of-care devices used by CPCT/A-level staff, such as glucometers, urine dipsticks, rapid strep tests, and hemoglobin/hematocrit analyzers, fall under CLIA-waived testing — simple tests carrying a low risk of an incorrect result. Even waived status does not remove quality obligations:

Control Levels for Waived Testing

Most CLIA-waived analyzers require testing with two levels of liquid control material — one at a low concentration and one at a high concentration — to confirm the device reads accurately across its reportable range rather than at only a single point. Facilities typically run these controls at the start of each day or shift, and whenever a new reagent lot or shipment of test strips is opened, comparing results against the manufacturer's or laboratory's acceptable range before any patient specimen is tested.

Dietary and Medication Restrictions for Nonblood Testing

Some nonblood tests require patient preparation similar to fasting for blood draws. A fecal occult blood test, for example, may require the patient to avoid red meat, certain vegetables, vitamin C supplements, and NSAIDs for several days beforehand, since these can cause false-positive or false-negative results. The CPCT/A should confirm any required preparation was followed and document deviations on the requisition. Blood culture bottles also carry printed fill-volume lines; underfilling reduces sensitivity, while overfilling can dilute the broth's growth-supporting ratio, so each bottle should be filled to its marked range.

Equipment Sterility and Expiration Checks

Before any collection, the phlebotomist or patient care technician must verify:

• Needle and tube packaging is intact and unopened — a torn or previously opened package cannot be considered sterile.
• Expiration dates on needles, tubes, lancets, alcohol prep pads, and culture bottles — expired tubes may have degraded additive or vacuum, producing inaccurate results.
• Tube vacuum integrity — a tube that fails to draw blood may have lost vacuum and should be discarded, not reused.
• Tourniquets and other reusable equipment are visibly clean, or single-patient-use and disposable, per facility infection-control policy.

Skipping these checks is a preventable source of specimen rejection, delayed diagnosis, and patient re-sticks, all outcomes the CPCT/A role exists to help avoid. Consistent adherence to aseptic technique, nonblood specimen protocols, waived-testing QC, and equipment checks protects both patients and the accuracy of every result the laboratory reports back to the care team.