What are general guidelines for specimens of patients with coronavirus disease 2019 (COVID-19)?

Updated: Jun 16, 2020
  • Author: Medscape Drugs & Diseases; more...
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Respiratory specimens

Upper respiratory tract [4]

For nasopharyngeal (NP) swabs/oropharyngeal (OP) swabs , use only synthetic fiber swabs with plastic or wire shafts. Do not use calcium alginate swabs or swabs with wooden shafts, as they may contain substances that inactivate some viruses and inhibit polymerase chain reaction (PCR) testing. The Centers for Disease Control and Prevention (CDC) now recommends collecting only the NP swab, although OP swabs remain an acceptable specimen type. If both swabs are used, NP and OP specimens should be combined into a single tube to maximize test sensitivity and limit use of testing resources. [4]

  • NP swab: Insert a minitip swab with a flexible shaft (wire or plastic) through the nostril parallel to the palate (not upward) until resistance is encountered or the distance is equivalent to that from the ear to the patient's nostril, indicating contact with the nasopharynx. The swab should reach a depth equal to the distance from the nostrils to the outer ear opening. Gently rub and roll the swab. Leave the swab in place for several seconds to absorb secretions. Slowly remove the swab while rotating it. Specimens can be collected from both sides using the same swab, but it is not necessary to collect specimens from both sides if the minitip is saturated with fluid from the first collection. If a deviated septum or blockage creates difficulty in obtaining the specimen from one nostril, use the same swab to obtain the specimen from the other nostril.

  • OP swab: Insert the swab into the posterior pharynx and tonsillar areas. Rub the swab over both tonsillar pillars and the posterior oropharynx; avoid touching the tongue, teeth, and gums.

For NP washes/aspirates or nasal washes/aspirates (NW/NA), attach a catheter to the suction apparatus. With the patient seated and head tilted slightly backward, instill 1 to 1.5 mL of nonbacteriostatic saline (pH 7.0) into one nostril. Insert the tubing into the nostril parallel to the palate (not upward). The catheter should reach a depth equal to the distance from the nostrils to the outer ear opening. Use gentle suction/aspiration and remove the catheter while rotating it gently. Collect the specimen in a sterile viral transport media tube.

For nasal midturbinate (NMT) swabs (also called deep nasal swabs), use a flocked tapered swab. Tilt patient’s head back 70º. While gently rotating the swab, insert the swab less than 1 inch (about 2 cm) into the nostril (until resistance is met at the turbinates). Rotate the swab several times against the nasal wall, and repeat this process in the other nostril using the same swab.

For anterior nares (NS) specimens, use a flocked or spun polyester swab. Insert the swab at least 0.5 inch (1 cm) inside the nostril and firmly sample the nasal membrane by rotating the swab and leaving it in place for 10 to 15 seconds. Sample both nostrils with the same swab.

Lower respiratory tract [4]

  • For bronchoalveolar lavage, tracheal aspirate, pleural fluid, or lung biopsy specimens, collect 2-3 mL into a sterile, leak-proof, screw-cap sputum collection cup or sterile dry container. Because increased technical skill and equipment is needed, collection of specimens other than sputum from the lower respiratory tract may be limited to patients who present with more severe disease, including those admitted to the hospital and/or fatal cases.

  • For sputum specimens, educate the patient about the difference between sputum and oral secretions (saliva). Have the patient rinse their mouth with water and then expectorate deep cough sputum directly into a sterile, leak-proof, screw-cap sputum collection cup or sterile dry container.

Storage and shipping

Store specimens at 2-8°C for up to 72 hours after collection. If a delay in testing or shipping is expected, store specimens at -70°C or below. [4]

Specimens must be packaged, shipped, and transported according to the current edition of the International Air Transport Association (IATA) Dangerous Goods Regulations. [4]

  • If specimens will ship to the CDC without delay, store specimens at 2-8°C, and ship overnight on an ice pack.

  • If a delay in shipping will result in the CDC receiving the specimen longer than 72 hours after collection, store specimens at -70°C or below and ship overnight to the CDC on dry ice.

  • Samples may be shipped to the CDC if repeated testing results remain inconclusive or if other unusual results are obtained. Contact the CDC at respvirus@cdc.gov prior to submitting samples.

  • Label each specimen container with the patient’s identification (ID) number (eg, medical record number), unique CDC or state-generated nCoV (novel coronavirus) specimen ID (eg, laboratory requisition number), specimen type (eg, serum), and the date the sample was collected.

  • Complete a CDC Form 50.34 for each specimen submitted. In the upper left box of the form, (1) for test requested; select “Respiratory virus molecular detection (non-influenza) CDC-10401” and (2) for At CDC, bring to the attention of enter “Unit 84 (Non-flu Resp Virus).”

  • Additional useful and detailed information on packing, shipping, and transporting specimens can be found at Interim Laboratory Biosafety Guidelines for Handling and Processing Specimens Associated with Coronavirus Disease 2019 (COVID-19)

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