Lab Procedures

1. A CCMA is performing a venipuncture on an adult patient in the antecubital fossa. The vein of first choice due to its size, stability, and location away from major structures is the:

The median cubital vein is the preferred site because it is large, well-anchored, and located away from the brachial artery and median nerve. The basilic vein lies near the brachial artery and median nerve, making it a last choice. The cephalic vein is a second option but tends to roll more than the median cubital.

2. A CCMA is drawing multiple tubes using the vacutainer system. According to CLSI order of draw, which tube should be collected immediately after the sodium citrate (light blue) tube?

The correct order of draw is: blood cultures, light blue (citrate), SST/serum tubes, green (heparin), lavender (EDTA), then gray (fluoride/oxalate). SST follows the citrate tube. Drawing EDTA or heparin too early can contaminate other tubes with additives that alter chemistry and coagulation results.

3. A patient requires a fingerstick capillary blood collection for a HemoCue hemoglobin. Which action is most appropriate?

The lateral aspect of the middle or ring finger is the recommended site, and the puncture should be perpendicular to the fingerprint lines so blood beads up rather than running down the grooves. The first drop is wiped away because it contains tissue fluid. Puncturing the center or squeezing vigorously causes pain and hemolysis; thumb and index finger are avoided due to calluses and nerve endings.

4. A CCMA is instructing a patient on how to provide a midstream clean-catch urine specimen. Which instruction is correct?

A midstream clean-catch requires the patient to cleanse the genital area, void a small amount into the toilet to flush the urethra of contaminants, and then collect the middle portion in the sterile container. Collecting the full void or the last drops increases contamination. Specimens should be transported promptly, not delayed by refrigeration if avoidable.

5. A urine dipstick shows positive leukocyte esterase and positive nitrites. This finding is most consistent with:

Positive leukocyte esterase indicates white blood cells (pyuria), and positive nitrites indicate the presence of gram-negative bacteria that convert dietary nitrates to nitrites—both classic findings for a UTI. Glucose would suggest diabetes, bilirubin/urobilinogen would suggest liver disease, and high specific gravity would suggest dehydration.

6. A CCMA performs a microhematocrit on a patient. After centrifugation, which layer is measured to determine the hematocrit value?

Hematocrit is the percentage of packed red blood cells in whole blood; the RBC layer at the bottom of the capillary tube is measured against the total column length. The plasma and buffy coat layers are not included in the hematocrit measurement, though the buffy coat represents leukocytes and platelets.

7. A CCMA is running quality control on the glucometer and the control result falls outside the acceptable range on the Levey-Jennings chart. What is the most appropriate next step?

When QC is out of range, patient testing must be halted, corrective action taken (new strips, new controls, recalibration, etc.), the action documented, and QC repeated successfully before running patient samples. Running patients with failed QC produces unreliable results and violates CLIA standards.

8. A provider orders a PT/INR on a patient taking warfarin. Which tube must be used, and what is a critical collection requirement?

PT/INR requires a light blue sodium citrate tube with a strict 9:1 blood-to-anticoagulant ratio, so it must be filled to the indicated fill line. Underfilled tubes produce falsely prolonged results. EDTA, SST, and heparin tubes are not used for coagulation testing.

9. A CCMA is performing a rapid strep A test on a school-age child. Which technique is correct for specimen collection?

A throat swab for strep A requires vigorous swabbing of both tonsillar areas and the posterior pharynx while avoiding contact with the tongue, teeth, and cheeks, which can dilute the specimen with normal flora. Nasal swabs are for respiratory viruses; saliva samples are inadequate for strep testing.

10. A CCMA is collecting a specimen for a chain-of-custody drug screen. Which action is required for legal defensibility?

Chain of custody requires documented, uninterrupted possession of the specimen with signatures from both donor and collector, tamper-evident seals, and continuous tracking of every person who handles the sample. Any break in the chain invalidates the specimen for legal purposes.

1. Under CLIA regulations, which of the following is classified as a waived test?

CLIA-waived tests are simple, low-risk procedures with minimal chance of error, such as visually read urine dipsticks, fecal occult blood, urine pregnancy, and glucose meters. Manual differentials, Gram stains, and automated CBCs are moderate or high complexity tests requiring additional personnel qualifications and QC.

2. A CCMA is performing a heelstick on a newborn. To avoid injuring the calcaneus, the puncture should be performed on the:

Heelsticks must be performed on the medial or lateral plantar surface of the heel to avoid puncturing the calcaneus bone, which can cause osteomyelitis. The center of the heel and the arch are too close to the bone and nerves, and toes are not used for heelstick collection in infants.

3. A CCMA collects a urine specimen that appears cloudy and has a strong ammonia odor. The most likely explanation is:

Cloudiness and a strong ammonia odor suggest bacterial contamination or prolonged specimen standing, during which bacteria convert urea to ammonia. Well-hydrated urine is typically pale and clear. Asparagus produces a distinctive odor but does not typically cause cloudiness.

4. A patient's CBC shows an elevated MCV of 110 fL. This finding is most consistent with:

MCV (mean corpuscular volume) measures RBC size; elevated MCV (>100 fL) indicates macrocytic RBCs, commonly caused by vitamin B12 or folate deficiency. Iron deficiency and thalassemia produce microcytic (low MCV) anemia. Sickle cell anemia typically shows a normocytic MCV with abnormal cell shape.

5. A CCMA is preparing to collect a blood specimen from a patient using the butterfly (winged infusion) set with a syringe on a small hand vein. When the first tube to be filled is a light blue (citrate) tube, what should the CCMA do?

When using a butterfly set, the tubing contains air that will cause an underfilled citrate tube and an incorrect blood-to-anticoagulant ratio. A discard tube (usually another citrate or non-additive tube) is drawn first to prime the line, ensuring the citrate tube fills completely to the line.

6. During a microscopic urinalysis, the CCMA identifies red blood cell casts. This finding is most clinically significant for:

RBC casts form in the renal tubules and indicate glomerular bleeding, associated with conditions like glomerulonephritis. They are never a normal finding. UTIs typically show WBC casts or bacteria, and dehydration produces concentrated urine but not RBC casts.

7. A CCMA is instructing a patient about a 24-hour urine collection. Which instruction is correct?

For a 24-hour urine collection, the patient discards the first morning void to start with an empty bladder, then collects every void for the next 24 hours, ending with the first void the following morning. The specimen typically must be kept refrigerated or on ice to preserve analytes.

8. A CCMA performs an ESR using the Westergren method. Which factor will falsely elevate the result?

Tilting the ESR tube causes red cells to fall faster along the side of the tube, falsely elevating the result. Correct technique requires a vertical tube, room temperature, no vibration or drafts, and reading at exactly 60 minutes with a properly anticoagulated specimen.

9. A CCMA is checking the refrigerator that stores reagents and specimens. The temperature log should be:

CLIA and lab accreditation standards require daily temperature monitoring and documentation of refrigerators, freezers, and room temperatures where reagents and specimens are stored. Out-of-range readings must be documented with corrective action to ensure reagent and specimen integrity.

10. A CCMA is collecting a nasopharyngeal swab for influenza testing. Which technique is correct?

A proper nasopharyngeal swab is inserted horizontally (parallel to the palate, not upward) along the nasal floor until it reaches the posterior nasopharynx, where it is rotated for several seconds to collect cells. Anterior nares sampling is inadequate for optimal viral detection, and directing the swab upward causes pain and inaccurate sampling.

1. A CCMA is performing a routine venipuncture in the antecubital fossa. Which vein is typically the first choice due to its size, stability, and location away from major nerves and arteries?

The median cubital vein is the preferred venipuncture site because it is large, well-anchored, and located away from the brachial artery and median nerve. The basilic vein lies close to the brachial artery and median nerve, increasing risk of injury. The cephalic vein is acceptable but tends to roll more than the median cubital.

2. A provider orders a PT/INR on a patient taking warfarin. Which tube should the medical assistant use to collect this specimen?

PT/INR and other coagulation studies require a light blue-top tube containing sodium citrate, which reversibly binds calcium to prevent clotting while preserving coagulation factors. EDTA is used for CBC, heparin for chemistry panels, and gray-top for glucose/lactate testing.

3. A CCMA is instructing a patient on how to collect a midstream clean-catch urine specimen. Which instruction is correct?

A midstream clean catch requires cleansing the genital area, voiding a small amount into the toilet to flush contaminants from the urethra, then collecting the middle portion into a sterile container. The first portion is discarded to reduce contamination, not collected. Refrigeration is done after collection if there is a delay in testing.

4. During a fingerstick capillary collection, which finger site is most appropriate?

The side of the fleshy pad of the middle or ring finger is the recommended site because it is less calloused and has fewer nerve endings than the center of the pad. The index finger is often calloused, the thumb has a pulse, and the fifth digit lacks sufficient tissue depth.

5. A urine dipstick shows a positive result for both leukocyte esterase and nitrites. These findings are most consistent with:

Leukocyte esterase indicates white blood cells in the urine, and nitrites indicate the presence of bacteria that convert urinary nitrates to nitrites — both are classic markers of a UTI. Glucose and ketones suggest diabetes, bilirubin/urobilinogen suggest liver disease, and high specific gravity suggests dehydration.

6. A CCMA performs quality control on the glucometer and finds that the control value falls outside the acceptable range. What is the correct next step?

When QC fails, patient testing must be halted, corrective action taken (new strips, recalibrate, new controls), and QC repeated and documented until acceptable results are obtained. Reporting patient results with failed QC violates CLIA regulations and compromises patient safety.

7. A CCMA is collecting a specimen using a butterfly (winged infusion) set with vacutainer tubes and only a coagulation test is ordered. What is the correct procedure?

When using a butterfly for coagulation testing, a discard tube must be drawn first to remove the air in the tubing, which would otherwise cause underfilling of the citrate tube and an inaccurate blood-to-additive ratio. Underfilling a blue-top tube produces falsely prolonged results.

8. A patient's microhematocrit result reads 42%. This value represents:

Hematocrit is the percentage of red blood cells relative to total blood volume, measured after centrifugation of a capillary tube. Plasma occupies the top layer, and the buffy coat (WBCs and platelets) is a thin layer between plasma and RBCs. Hemoglobin is a separate measurement expressed in g/dL.

9. Which of the following tests is classified as CLIA-waived and can be performed by a CCMA with minimal training?

Urine dipstick (visual) is a CLIA-waived test that requires minimal training and has a low risk of erroneous results. Manual differentials, Gram stains, and manual coagulation tests are classified as moderate or high complexity because they require significant technical skill and interpretation.

10. A CCMA is collecting a nasopharyngeal swab for influenza testing. Which technique is correct?

A nasopharyngeal swab is inserted parallel to the palate (not upward) until it reaches the nasopharynx, then rotated to collect epithelial cells. Anterior nares sampling is insufficient for many respiratory pathogens. Wooden shafts and cotton tips can inhibit viral detection; synthetic swabs are required.

1. A patient's ESR is markedly elevated using the Westergren method. This result most likely indicates:

The erythrocyte sedimentation rate is a nonspecific marker of inflammation; it rises with infections, autoimmune disorders, and malignancies. Dehydration does not typically elevate ESR, iron deficiency alone is not the primary cause, and elevated values are not a normal finding.

2. When collecting a 24-hour urine specimen, the medical assistant should instruct the patient to:

For a 24-hour urine collection, the patient discards the first morning void to start with an empty bladder, then collects all urine for the next 24 hours, ending with a final morning void at the same time the next day. The entire collection must be kept refrigerated or on ice throughout.

3. A CCMA is performing a rapid strep A test. The internal control line appears, but no test line appears after the required time. This result should be reported as:

When the control line appears (indicating the test worked properly) but no test line develops, the result is negative for group A strep. A positive result requires a visible test line. An invalid result would occur only if the control line failed to appear.

4. According to the CLSI order of draw, which sequence is correct after a blood culture?

The correct order of draw is: blood cultures, light blue (citrate), red/SST/gold (serum), green (heparin), lavender (EDTA), then gray (fluoride/oxalate). This order minimizes cross-contamination of additives between tubes, which could alter test results.

5. A CCMA notes that the laboratory refrigerator temperature is reading 2°F above the acceptable range during morning checks. What is the appropriate action?

Out-of-range temperatures require immediate documentation, corrective action (e.g., adjusting the thermostat, notifying maintenance, moving reagents), and documentation of the corrective action per CLIA and CLSI requirements. Ignoring or delaying action jeopardizes specimen integrity and test validity.

6. A urinalysis reveals cloudy urine with a positive nitrite result. Microscopic examination is most likely to reveal:

Cloudy urine with positive nitrites suggests a bacterial UTI, and microscopic examination will typically reveal bacteria and white blood cells (pyuria). Hyaline casts are associated with dehydration or exercise, calcium oxalate crystals with certain metabolic conditions, and yeast alone would not produce positive nitrites.

7. A CCMA collects a specimen for drug screening under chain of custody. Which action is required?

Chain of custody requires that the specimen be sealed with tamper-evident tape, labeled in the patient's presence, and documented with signatures each time the specimen changes hands to maintain legal defensibility. Patients cannot transport their own specimen, and the specimen must never be left unattended.

8. A CCMA is reviewing a Levey-Jennings chart for glucose control results. Ten consecutive results fall on the same side of the mean but within ±2 SD. This pattern indicates:

A shift is defined as six or more (commonly 10) consecutive results falling on the same side of the mean, indicating a systematic error such as a new lot of reagent or a change in instrument calibration. A trend shows progressively increasing or decreasing values. Investigation and corrective action are required.

9. A CCMA is performing a heelstick on a newborn. Which site is appropriate?

Heelsticks should be performed on the medial or lateral plantar surface of the heel to avoid injury to the calcaneus (heel bone). Puncturing the arch or posterior curvature risks nerve, tendon, or bone injury. The great toe is not an approved capillary site for infants.

10. A stool specimen is being collected for ova and parasite (O&P) examination. Which instruction should the CCMA give the patient?

O&P specimens should be collected in a container with the appropriate preservative (such as formalin and PVA) and must not be contaminated with urine, toilet water, or toilet paper, which can destroy parasites and affect results. Freezing destroys parasites, and blood is not required for the test.

1. A CCMA is performing a routine venipuncture in the antecubital fossa. Which vein is the preferred first choice for selection?

The median cubital vein is the preferred site because it is typically large, well-anchored, and located away from major nerves and arteries. The basilic vein is a last resort due to its proximity to the brachial artery and median nerve. The cephalic vein is a second choice, and the median antebrachial is not typically used for routine venipuncture.

2. A physician orders a PT/INR on a patient taking warfarin. Which tube must the CCMA use to collect this specimen?

PT/INR (coagulation) testing requires a light blue-top tube containing sodium citrate, which must be filled to the exact fill line to maintain the 9:1 blood-to-anticoagulant ratio. EDTA is used for CBCs, heparin for chemistry, and gray-top for glucose/lactate testing.

3. A CCMA is performing a heelstick on a newborn for a bilirubin level. Which area of the heel is the correct puncture site?

The medial and lateral plantar surfaces of the heel are the only safe puncture sites because they avoid the calcaneus bone, which could be injured causing osteomyelitis. The center and posterior curvature are too close to the bone, and random selection is unsafe.

4. A patient is instructed to collect a midstream clean-catch urine specimen. Which instruction is correct?

For a midstream clean catch, the patient cleanses the genital area, begins urinating into the toilet to flush contaminants from the urethra, then collects the middle portion in the sterile cup. Collecting the first portion introduces contaminants, and this test is not a timed collection.

5. During urinalysis dipstick testing, which combination of positive results most strongly suggests a urinary tract infection?

Positive leukocyte esterase indicates the presence of white blood cells, and positive nitrites indicate gram-negative bacteria (such as E. coli) converting urinary nitrates. Together they strongly suggest UTI. Glucose/ketones suggest diabetes, bilirubin/urobilinogen suggest liver disease, and protein/specific gravity suggest renal or hydration issues.

6. A CCMA is performing a microhematocrit test. After centrifugation, which layer represents the packed red blood cells used to determine the hematocrit value?

The red bottom layer represents packed red blood cells and is measured against the reference scale to determine the hematocrit percentage. The top yellow layer is plasma, the buffy coat contains WBCs and platelets, and the clay sealant is used to prevent leakage during centrifugation.

7. A CCMA is performing daily quality control on the glucose meter and the control result falls outside the acceptable range on the Levey-Jennings chart. What is the appropriate next action?

When QC is out of range, patient testing must be stopped until the cause is identified (expired strips, improper storage, calibration issue) and corrected, and QC is repeated successfully. Documenting only, testing patients, or discarding the meter without troubleshooting are inappropriate and could produce inaccurate patient results.

8. A CCMA is collecting a nasopharyngeal swab for influenza testing. Which technique is correct?

A proper nasopharyngeal swab is inserted straight back (parallel to the palate, not upward) until resistance is met at the nasopharynx, then rotated for several seconds to collect epithelial cells. Anterior nares collection is insufficient for NP testing, aiming toward the eye is anatomically incorrect and unsafe, and blowing the nose is not an acceptable collection method.

9. A CCMA is drawing multiple tubes using the vacutainer system. What is the correct order of draw after blood culture bottles?

After blood cultures, the correct order of draw is: light blue (citrate), SST/red (serum), green (heparin), lavender (EDTA), then gray (fluoride/oxalate). This order minimizes cross-contamination between additives that could alter test results.

10. Under CLIA regulations, which of the following tests is classified as waived complexity?

Dipstick urinalysis is a CLIA-waived test because it is simple, has minimal risk of error, and can be performed by personnel with minimal training. Manual differentials, Gram stains, and microscopic urinalysis are moderate or high complexity tests requiring specialized training and more stringent regulatory oversight.