Influenza virus PCR

TEST DESCRIPTION

Detection of influenza A and B viruses by reverse-transcription polymerase chain reaction (RT-PCR) in patients with respiratory illness. Using the Centers for Disease Control and Prevention (CDC) Influenza PCR protocol, the following viruses are detected:

• Influenza A, subtypes pandemic H1, H3, H5*, H7*
• Influenza B

*If meeting the clinical and epidemiologic criteria for testing suspect A/H5 and/or A/H7 specimens.

Methodology

RT-PCR

Reference range

Negative

TEST FREQUENCY & RESULT AVAILABILITY

Performed Monday, Wednesday, and Friday. Results are typically available two business days after specimen receipt.

ACCEPTABLE SPECIMEN TYPES AND COLLECTION

• Preferred: Nasopharyngeal swab in viral transport medium (VTM)
• Nasal swab in VTM
• Throat swab in VTM
• Nasal wash in VTM
• Bronchial wash or lavage
• Tracheal aspirates
• Sputum
• Detailed collection instructions appear below

SPECIMEN STORAGE

Store refrigerated (2°C–8°C/35.6°F–46.4°F) for up to 72 hours. 

SPECIMEN TRANSPORT

Shipping conditions should follow the temperature and time requirements outlined above.

REJECTION CRITERIA

• Holding time greater than 72 hours
• Specimen container not labeled 
• Specimen container has leaked or is not sealed properly 
• Swab specimens that are missing the swab, contain multiple swabs, or contain the wrong swab

CODES

CPT: 87501
LOINC: 48509-4
Test code: 50001

TEST FEE

Refer to the current fee schedule.

DETAILED SPECIMEN COLLECTION INSTRUCTIONS

1. Collect respiratory specimens during acute phase of illness
2. Nasopharyngeal swab in VTM
   1. Ask the patient to blow their nose to clear their nasal passage and tilt the patient’s head backwards.
   2. Swiftly insert the small swab into one nostril straight back (not upwards) at a depth equal to distance from nostrils to outer opening of the ear (see image). 
   3. Firmly rotate the swab up to 5 times and hold in place for 5-10 seconds to collect epithelial cells. 
   4. Repeat with the other nostril using the same swab. 
   5. Snap the swab at the scored breakpoint line; place swab into VTM tube; close the tube tightly and place in a biohazard bag.
3. Nasal swab in VTM
   1. Tilt patient’s head back 70 degrees.
   2. While gently rotating the swab, insert  swab less than one inch into nostril (until resistance is met at turbinates).
   3. Rotate the swab several times against nasal wall.
   4. Repeat in other nostril using the same swab.
   5. Place the swab into VTM.
4. Throat swab in VTM
   1. Vigorously swab tonsillar areas with sterile synthetic swab. Place swab in VTM.
5. Nasal wash/aspirate in VTM
   1. Use a syringe attached to a small, plastic tube and 2-3 ml of VTM. After placing the VTM in the nose, aspirate as much of the material as possible and rinse the tube with 2 ml of VTM.
6. Bronchial wash or lavage
   1. These specimens are collected in a clinical setting, and appropriate for patients unable to produce sputum.
   2. The clinician should collect as much material as is reasonably possible. Although there is no minimum volume, the recommended volume is ≥3 ml.
7. Tracheal aspirate
   1. Collect 2-3 mL into a sterile, leak-proof, screw-cap collection container.
8. Sputum
   1. Rinse throat and mouth with water (do not brush teeth or use mouthwash).
   2. Cough very deeply and collect between 5 and 10 mL of sputum (about an inch high) into the specimen tube. Sputum is the mucus material from inside the lungs. Do not collect saliva or nasal discharge.
   3. Tightly screw the cap onto the tube. If the cap is crooked, your specimen may leak and will be rejected.
   4. Optimal collection is 5-10 ml of sputum in a clean, sterile, leak-proof, screw-cap container. Minimum specimen volume is 1 ml.