6.12 Non-Blood Specimen Collection

6.12 Non-Blood Specimen Collection

Although phlebotomists primarily collect venous blood, they are frequently responsible for instructing patients on non-blood specimen collection, verifying specimen adequacy, and managing pre-analytical processing for non-blood samples. Because non-blood specimens are often collected by patients themselves, clear verbal and written instructions are essential to prevent cross-contamination and invalid test results.

Urine Specimen Collection Protocols

Urine is the most common non-blood clinical specimen. Test validity depends entirely on selecting the appropriate collection method and maintaining proper preservation conditions.

Types of Urine Collections

Step-by-Step Clean-Catch Midstream (CCMS) Patient Instruction

1. Hand Hygiene: Patient washes hands thoroughly with soap and water before opening the kit.
2. Cleansing Technique:
   • Female Patients: Separate labia with one hand; use provided antiseptic wipes (castile soap or benzalkonium chloride) to cleanse from front to back (anterior to posterior) down one side, front to back down the other side, and front to back down the center. Use a fresh wipe for each stroke.
   • Male Patients: Retract foreskin if uncircumcised; cleanse the tip of the penis (urethral meatus) in a circular motion, moving from the center outward. Use fresh wipes.
3. Midstream Capture: Instruct the patient to begin voiding into the toilet. Without stopping the flow, pass the sterile container into the urine stream to capture the middle portion (approx. 30 to 60 mL). Remove the container and finish voiding into the toilet.
4. Sterile Handling: Avoid touching the inside of the container or lid. Secure lid tightly and return to laboratory staff.

Preservation & Transport

Urine specimens must be analyzed within 2 hours of collection. If testing is delayed, the specimen must be refrigerated at 2°C to 8°C or preserved in specialized urine transport tubes (e.g., grey-top tubes containing boric acid for C&S, or yellow/red cherry-top tubes for urinalysis) to prevent bacterial overgrowth, cellular degradation, and pH shifts.

Respiratory Sputum Specimen Protocols

Sputum is a thick, mucomucoid secretion generated deep within the lower respiratory tract (trachea, bronchi, and lungs). It is collected to evaluate lower respiratory infections such as bacterial pneumonia, tuberculosis (acid-fast bacilli / AFB culture), and fungal infections.

Collection Rules & Guidelines

• Timing: First morning specimens are preferred because secretions accumulate in the lungs overnight.
• Oral Care: Patient should rinse their mouth with water only before collection to remove food debris and loose oral flora. Toothpaste, mouthwash, or antiseptic rinses must be avoided because they suppress microbial growth.
• Deep Cough Technique: Patient must take several deep diaphragmatic breaths, hold their breath briefly, and produce a deep cough from deep within the chest to expectorate into a sterile, wide-mouth container.
• Quality Verification: Phlebotomists must inspect the specimen to ensure it is true sputum (thick, viscous, purulent, or blood-tinged) and not saliva (clear, watery, bubbly fluid). Saliva contains squamous epithelial cells that render cultures invalid.

Stool (Fecal) Specimen Protocols

Fecal collections are ordered to evaluate gastrointestinal disorders, occult bleeding, parasitic infections, and bacterial enteritis.

Fecal Occult Blood Test (FOBT / Guaiac)

Guaiac-based FOBT detects hidden (occult) blood in stool, serving as a primary screening tool for colorectal cancer and GI lesions. Guaiac paper relies on a chemical reaction sensitive to peroxidase activity.

• Dietary & Medication Restrictions (72 Hours Prior): To prevent false-positive or false-negative results, patients must strictly avoid:
  • Red Meat: Animal hemoglobin causes false positives.
  • Vitamin C & Citrus ( >250 mg/day): Ascorbic acid blocks peroxidase reaction, causing false negatives.
  • Raw Vegetables: Turnips, horseradish, radishes, and cantaloupe contain plant peroxidases (false positives).
  • Medications: Aspirin, NSAIDs (ibuprofen, naproxen), and iron supplements cause micro-bleeding (false positives).

Ova and Parasite (O&P) Collections

For intestinal parasite identification (e.g., Giardia, Entamoeba), stool must be collected without urine or toilet water contamination (water destroys delicate protozoan trophozoites). Specimens are placed into dual-vial transport systems containing 10% formalin and polyvinyl alcohol (PVA) fixatives.

Microbiological & Viral Swab Techniques

Mucosal swabs are collected to identify pathogenic bacteria, viruses, and fungi residing on epithelial surfaces.

Throat Swab (Pharyngeal Swab)

• Indication: Diagnosing Group A Beta-Hemolytic Streptococcus ("strep throat"), diphtheria, or viral pharyngitis.
• Procedure:
  1. Position patient with head tilted back under good lighting.
  2. Depress the tongue using a sterile wooden tongue depressor.
  3. Pass a sterile Dacron or rayon swab over the posterior pharynx, palatine tonsils, and any inflamed or purulent exudative areas using a firm figure-eight motion.
  4. Critical Safety Rule: Carefully insert and withdraw the swab without touching the tongue, lips, teeth, or uvula to avoid contaminating the specimen with normal oral flora.

Nasopharyngeal (NP) Swab

• Indication: Diagnosing viral respiratory pathogens including Influenza A/B, RSV, SARS-CoV-2, and Bordetella pertussis.
• Procedure:
  1. Use a flexible mini-tip swab with a synthetic polyester or flocked shaft (never use cotton or calcium alginate swabs, as they inhibit viral PCR testing).
  2. Measure distance from nostril to outer opening of the ear to gauge insertion depth.
  3. Gently insert swab through the nostril parallel to the palate (straight back, not upward) until resistance is met at the posterior nasopharynx.
  4. Gently rotate the swab 3 to 5 seconds to absorb secretions, then slowly withdraw.
  5. Place swab into Viral Transport Medium (VTM) or Universal Transport Medium (UTM) and transport immediately on ice.