BNS Section 10: Specimen Collection

Section Overview

Accurate specimen collection is the foundation of valid laboratory diagnosis. A poorly collected, incorrectly labeled, improperly stored, or inadequately transported specimen produces results that are unreliable — leading to delayed diagnoses, unnecessary repeat testing, incorrect treatments, and patient harm. Nurses are responsible for much of the specimen collection that occurs in acute care settings, and they serve as educators when patients must collect their own specimens.

This section covers the most common specimen types encountered in BSN clinical practice: blood (venipuncture), urine (clean-catch, catheter, 24-hour), stool (occult blood, culture, C. difficile), sputum, and wound cultures. For each type, the nurse must understand the clinical purpose, patient preparation requirements, collection technique, labeling requirements, transport considerations, and patient education.

---

Learning Objectives

By the end of this section, students will be able to:

1. Describe the purpose, preparation, and correct collection technique for blood, urine, stool, sputum, and wound specimens. (Bloom’s: Understand)
2. Apply standard precautions and correct labeling and transport procedures to all specimen collection activities. (Bloom’s: Apply)
3. Instruct patients in the correct self-collection technique for midstream clean-catch urine and stool specimens. (Bloom’s: Apply)
4. Identify pre-collection conditions and patient preparation requirements that affect the validity of laboratory specimens. (Bloom’s: Understand)
5. Interpret common findings in urinalysis and basic metabolic panels to recognize values requiring provider notification. (Bloom’s: Analyze)
6. Document specimen collection accurately, including collection time, method, transport conditions, and relevant patient status. (Bloom’s: Apply)

---

General Principles of Specimen Collection

Standard Precautions in Specimen Collection

All specimens are treated as potentially infectious. At minimum, the nurse wears clean gloves during all specimen collection activities. Additional PPE (gown, mask, eye protection) is used if splashing or aerosolization of body fluids is possible (e.g., sputum induction, wound irrigation).

Specimens are collected into the appropriate sealed container, labeled immediately at the bedside, and transported in a biohazard bag with the laboratory requisition placed in the outer pocket (not inside with the specimen).

Labeling Requirements

Every specimen must be labeled immediately at the point of collection, before leaving the patient’s bedside. Required label elements:

• Patient’s full legal name
• Date of birth (or second unique identifier per facility policy)
• Medical record number
• Date and time of collection
• Collector’s name or initials
• Type of specimen (when not pre-printed)
• Relevant clinical information (e.g., antibiotic use for cultures; fasting status for glucose)

Unlabeled or mislabeled specimens will be rejected by the laboratory; recollection delays care and adds discomfort for the patient.

---

Blood Specimen Collection

Blood specimens are obtained by venipuncture (peripheral vein) or from an existing central venous catheter or arterial line per facility policy and scope of practice.

Common Blood Tests and Clinical Significance

Test	Normal Adult Range	Clinical Use
WBC	4,500–11,000 cells/µL	Infection, inflammation, immune status
RBC / Hemoglobin / Hematocrit	Hgb: M 13.5–17.5; F 12.0–15.5 g/dL	Anemia, polycythemia, blood loss
Platelets	150,000–400,000/µL	Bleeding risk, thrombocytopenia
Sodium	135–145 mEq/L	Fluid/electrolyte balance, renal function
Potassium	3.5–5.0 mEq/L	Cardiac arrhythmia risk; monitor in renal disease
Glucose (fasting)	70–100 mg/dL	Diabetes management, hypoglycemia/hyperglycemia
BUN / Creatinine	BUN 7–25; Cr 0.6–1.3 mg/dL	Renal function, hydration status
INR	0.8–1.2 (therapeutic 2.0–3.0 on warfarin)	Coagulation; warfarin monitoring
aPTT	25–35 seconds (therapeutic 60–100 on heparin)	Coagulation; heparin monitoring
Troponin I/T	< 0.04 ng/mL (varies by assay)	Myocardial injury; MI diagnosis
Lactate	0.5–2.2 mmol/L	Tissue perfusion; sepsis assessment

Order of Draw

When multiple blood tubes are collected in a single venipuncture, tubes must be filled in the correct sequence to prevent additive cross-contamination between tubes (the Order of Draw):

1. Blood culture bottles (aerobic then anaerobic)
2. Light blue (sodium citrate) — coagulation studies; fill to the line exactly
3. Red / Gold (SST — serum separator tube) — chemistry, serology
4. Green (lithium heparin) — chemistry stat
5. Lavender / Purple (EDTA) — CBC, differential
6. Pink (EDTA) — blood bank / type and screen
7. Gray (potassium oxalate) — glucose, lactate

A memory device: “Boys Love Rope Guns, Loose Pistols Gray” (Blue, Light blue, Red/Gold, Green, Lavender, Pink, Gray).

Venipuncture Technique

1. Verify the order and gather supplies; perform hand hygiene and don gloves
2. Select a vein (antecubital fossa preferred; cephalic, basilic, or median cubital veins); apply tourniquet 3–4 inches above the intended site; ask the patient to make a fist
3. Cleanse the site with 70% isopropyl alcohol in a circular motion; allow to dry completely (30 seconds) — do not blow or fan dry
4. Anchor the vein; insert the needle bevel-up at a 15–30° angle; advance smoothly until blood appears in the flash chamber
5. Fill tubes in the correct order of draw; invert each tube the required number of times per manufacturer instructions
6. Release the tourniquet before withdrawing the needle; apply pressure with gauze after withdrawal (do not recap the needle)
7. Dispose of the needle immediately in the sharps container; label tubes at the bedside

NCLEX-Style Practice Question:

A nurse is collecting blood specimens from a patient for a CBC and coagulation studies. In which order should the nurse fill the tubes?

• A) Lavender (EDTA) first, then light blue (citrate)
• B) Light blue (citrate) first, then lavender (EDTA) ✓
• C) Red (SST) first, then light blue, then lavender
• D) Order does not matter as long as all tubes are drawn from the same venipuncture

---

Urine Specimen Collection

Midstream Clean-Catch Urine

The midstream clean-catch (MSCC) specimen is used for urinalysis (UA) and urine culture and sensitivity (C&S). Proper technique minimizes perineal flora contamination and ensures a valid result.

Patient instruction (teach-back):

Female:

1. Wash hands thoroughly
2. Open the specimen container without touching the inside of the cup or lid
3. Separate the labia with one hand and keep them separated throughout collection
4. Use the antiseptic wipe provided — wipe front to back, one stroke; use a fresh wipe for each stroke (at least 2–3 wipes)
5. Begin urinating into the toilet; after the first 1–2 seconds, move the cup into the stream and collect 20–30 mL; remove the cup before urine flow ends
6. Cap the container and deliver to the nurse immediately

Male:

1. Wash hands; retract foreskin (if uncircumcised) and maintain throughout collection
2. Cleanse the glans in a circular motion from the urethral meatus outward using antiseptic wipes
3. Begin urinating; collect midstream portion; recap and deliver promptly

Catheter Specimen of Urine

When an indwelling catheter is in place, urine is collected from the specimen port using a sterile syringe — never from the drainage bag (which may contain old, colonized urine) and never by disconnecting the catheter from the drainage tubing.

1. Clamp the tubing below the port for 15 minutes to allow fresh urine to accumulate
2. Cleanse the port with an alcohol swab and allow to dry
3. Insert a sterile syringe into the port and aspirate the required volume (typically 10 mL)
4. Transfer to the appropriate sterile specimen container; label and send

24-Hour Urine Collection

The 24-hour collection measures the total amount of a substance (e.g., creatinine clearance, protein, cortisol) excreted over an entire day. Accuracy depends entirely on complete collection.

• The collection begins after the patient voids and discards that first specimen; the clock starts at that time
• All subsequent urine — including the final void at the end of the 24-hour period — goes into the large collection container
• The container must be kept on ice or refrigerated throughout collection unless otherwise specified (some analytes require a preservative-containing container)
• If a specimen is accidentally discarded during the collection period, the collection must start over

---

Stool Specimen Collection

Types of Stool Tests

Test	Purpose	Collection Notes
Fecal occult blood test (FOBT)	Screen for GI bleeding; colon cancer screening	Collect from three separate areas of stool; patient may need to avoid red meat, NSAIDs, and vitamin C for 3 days pre-collection per provider instructions
Stool culture (bacterial)	Identify pathogens (Salmonella, Shigella, Campylobacter, E. coli O157:H7)	Collect in clean container; send immediately or refrigerate; do not use bedpan with urine contamination
Clostridioides difficile toxin	Diagnose C. diff colitis	Must be liquid or unformed stool only — formed stool is rejected by the lab; send to lab promptly
Ova and parasite (O&P)	Identify intestinal parasites	May require multiple collections on separate days; check lab requirements
Fecal fat (72-hour stool collection)	Assess fat malabsorption	All stool collected over 72 hours while on a high-fat diet

Patient instruction for stool collection: Defecate into a collection hat (basin) placed under the toilet seat; use the provided spoon or spatula to transfer a walnut-sized sample into the container; do not contaminate with urine or toilet paper; deliver to the nurse promptly.

---

Sputum Specimen Collection

Sputum specimens are used to diagnose respiratory infections including pneumonia, tuberculosis, and fungal lung infections.

Principles of Valid Sputum Collection

A valid sputum specimen contains lower respiratory secretions — not saliva. The laboratory will reject a specimen with > 25 squamous epithelial cells per low-power field (indicating it is predominantly saliva rather than sputum).

Timing: Collect early morning (first specimen upon awakening) when secretions are most concentrated and patients have not yet swallowed overnight respiratory secretions.

Patient preparation:

• Have the patient rinse the mouth with water (not mouthwash, which contains antibacterial agents that can contaminate culture results) before collection
• Do not collect after the patient has just eaten — risk of emesis

Collection technique:

1. Instruct the patient to take two to three deep breaths, then cough forcefully from the diaphragm on exhalation
2. Collect expectorated sputum (not saliva) directly into the sterile container — at least 5 mL required for most tests
3. For patients unable to produce sputum voluntarily, inhaled hypertonic saline nebulization (sputum induction) may be ordered

Safety note: Sputum induction carries an aerosolization risk. Always use a negative-pressure room and N95 respirator for sputum collection from patients with suspected or confirmed pulmonary tuberculosis.

---

Wound Specimen Collection

Wound cultures are collected to identify the causative organisms in an infected wound and guide antibiotic selection. The most common method in clinical nursing practice is the swab culture, though biopsy and aspirate cultures provide more accurate results in some circumstances.

Swab Culture Technique (Levine Method)

1. Cleanse the wound with normal saline to remove surface exudate and necrotic tissue (do not cleanse with antiseptic — this can kill surface bacteria and invalidate culture results)
2. Using a sterile culture swab, apply firm pressure and a zigzag pattern across 10 different points in the clean, viable wound bed (not the wound edges or necrotic tissue)
3. The swab should become moist with wound fluid; if the wound is dry, moisten the swab with sterile saline first
4. Insert the swab into the culture transport medium; label and transport to the laboratory within 30 minutes (or per lab protocol)

Important: Wound cultures represent colonizing organisms in the wound bed, not necessarily the infecting organism. Culture results must always be interpreted alongside clinical assessment findings (signs of local infection: increased erythema, warmth, swelling, purulent exudate, pain; signs of systemic infection: fever, elevated WBC).

NCLEX-Style Practice Questions:

1. A nurse is preparing to collect a midstream clean-catch urine specimen from a female patient. After providing instructions, the nurse uses teach-back to verify understanding. Which patient statement indicates the need for further teaching?

   • A) “I will wash my hands before touching the cup.”
   • B) “I will keep my labia separated during the whole collection.”
   • C) “I will collect the first part of my urine stream in the cup.” ✓
   • D) “I will give the specimen to the nurse right away.”

2. A nurse collects a wound culture from a patient with a stage 3 pressure injury on the sacrum. The wound has a moderate amount of tan exudate and the periwound skin is erythematous. Which collection technique is correct?

   • A) Swab the wound exudate and any necrotic tissue for the most accurate result
   • B) Irrigate with antiseptic solution to reduce surface contaminants before swabbing
   • C) Apply firm pressure and use a zigzag pattern across the clean, viable wound bed ✓
   • D) Collect exudate from the wound edges where infection typically originates

---

Standards Alignment

This section supports the following professional and regulatory frameworks:

• AACN Essentials D1, D2, D3, D9: Knowledge for nursing practice; person-centered care; population health
• NCLEX-NG CJMM: Recognize Cues (RC), Analyze Cues (AC), Prioritize Hypotheses (PH), Generate Solutions (GS)
• QSEN: Patient-Centered Care (PCC), Evidence-Based Practice (EBP), Safety (S), Quality Improvement (QI)
• CCNE Standards I, II: Professional identity; curriculum outcomes
• ACEN Standards 3, 4: Student outcomes; specimen collection and laboratory interpretation curriculum content