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Test Code M231 Norovirus RNA Detection by PCR

Performing Laboratory

Barnes-Jewish Hospital Laboratory


  Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) using the Cepheid Xpert Norovirus assay performed on the GeneXpert System


Literature Reference: 

Xpert® Norovirus Assay – GeneXpert Package Insert.  Cepheid, Sunnyvale, CA.  301-2441, Rev. B January 2015.                                            

Specimen Requirements

Acceptable Specimens

≥1 mL of fresh liquid or non-formed stool  in a leakproof screw-capped, sterile container


Unacceptable Specimen:
Solid or formed stool

  Collection Procedure:

1. Collect ≥1 mL of fresh liquid or non-formed stool.
2. Place specimen in a leakproof screw-capped, sterile container. (Stool in container with preservative is not acceptable.)
3. Maintain sterility and forward promptly.
4. If transport is delayed, refrigerate specimen. If specimen will be in transport > 4 hours, transport with ice pack.
Note: 1. Specimen source is required.
2. Specimen should not be collected following a barium enema.

3. Previously frozen specimen is acceptable.                                         

Day(s) Test Set Up

Monday through Sunday
Turnaround Time:
STAT: not available
Routine: 8 hours

Reference Values

Norovirus target RNA sequences are not detected (Negative)

Test Classification and CPT Coding

Test Classification:

This test is performed using the Cepheid GeneXpert Dx System Norovirus assay. This test is U.S. Food and Drug Administration (FDA)-approved for testing of unformed stool. The performance characteristics have been determined by Barnes-Jewish Hospital Microbiology Laboratory.


CPT Code:

87798 X2

Additional Information

For BJH Laboratory Use Only
Minimum Volume
1 mL of fresh liquid or non-formed stool  in a leakproof screw-capped, sterile container



Specimen Transport Temperature

Ambient OK (within 4 hours)/Refrigerate OK (within 48 hours)/Frozen OK


Positive Xpert Norovirus results do not rule out other causes of infectious diarrhea.  Assay interference may be observed in the presence of Barium sulfate and Benzalkonium chloride.  Mutations or polymorphisms in primer or probe binding regions may affect detection of new or unknown norovirus variants resulting in a false negative result.  Results from the Xpert Norovirus Assay should be interpreted in conjunction with other laboratory and clinical data available to the clinician.