UCSF Navigation Bar

UCSF Departments of Pathology & Laboratory Medicine Home Page

Lab Manual for UCSF Clinical Laboratories

Lab Manual for SFGH

Internal Resources


Item Value
Available Stat? No
Test code RSVA (rapid immunoassay)
DFRSV (direct FA)
Performed by? Microbiology , rapid immunoassay;
Reference Laboratory, direct FA
Sendout? no, rapid immunoassay;
yes, direct FA
Price range $$$
In House Availability Note: Test method is determined by season and patient age:
Age ≤ 5 years Done during
RSV season
turn-around-time: 1 hour
Done outside
of RSV season
turn-around-time: 1-3 days
Age > 5 years Not done Done year-round.
turn-around-time: 1-3 days

Rapid immunoassay:
Because of the poor sensitivity of the immunoassay for detecting RSV in older children and adults, this test is restricted to children ages 5 and under. Because of the low predictive value of a positive (high likelihood of false positive results) when the prevalence of RSV is low, this test is offered only when respiratory syncytial virus is circulating in the community.

RSV Direct FA: 7 days throughout the year. Sent to reference lab for patients older than 5 years of age during RSV season. Sent to a reference lab for all patients outside of RSV season.
Principle Rapid immunoassay: Specimen migrates down a nitrocellulose membrane that contains anti-RSV antibody conjugated to visualizing particles. A pink line is seen when RSV antigen is present.

RSV Direct FA: Washed cells are fixed on a slide and stained with fluorescent monoclonal antibody to RSV.
Interpretation Rapid immunoassay: A positive test suggests the presence of RSV. A negative test may indicate the absence of RSV or may be falsely negative due to improper specimen collection, improper specimen handling, or virus amounts lower than the level detectable by the test.

In studies in our laboratory, the rapid immunoassay was 95% sensitive (compared to culture and/or direct fluorescent antibody test) for detection of RSV in children, and 33% sensitive for detection of RSV in adults.

RSV Direct FA: A positive test indicates the presence of RSV. A negative test may indicate the absence of RSV or virus amounts lower than the level detectable by the test. Specimens with inadequate numbers of cells will be reported as "Inadequate specimen."

CLINICAL SIGNIFICANCE: Results must be interpreted in conjunction with clinical findings and other laboratory data.
Container type 1. Put wash/aspirate specimens in sterile, leak proof containers.

2. For NP swab specimen, use swabs provided with viral transport medium (obtained from Lab Support Services, 206-8199) for collecting specimens. If viral transport packages are not available, dacron swabs with plastic or fine-wire shafts may be used and placed into a small amount (approx. 0.5 ml) of sterile non-bacteriostatic saline in a sterile tube. DO NOT USE CALCIUM ALGINATE SWABS.
Collection Instructions Wash/aspirate: Have patient recline at 45 degrees so that saline introduced does not directly flow out. Introduce a few drops to 1 mL of sterile saline (from a pink respiratory therapy ampule) into anterior nares. Insert an appropriate sized catheter (usually about #6 or #8 French) into the nose to the distance between the nares and the ear or until resistance is encountered. Suction intermittently through a mucus or DeLee specimen trap. Remove catheter and flush the line with no more than 2 mL of saline. Use of larger volumes will dilute the specimen and diminish the sensitivity of the test. Seal collection container.

Nasopharyngeal swab: Insert swab through a nostril and into the posterior nasopharnyx and rotate the swab several time sto collect mucosal epithelium. After collecting specimen, aseptically break swab into tube of transport medium and cap tightly.
Sample type Nasal or nasopharyngeal wash; nasopharyngeal swab
Normal range No antigen detected.
Synonyms Nasopharyngeal Aspirate, Viral Detection from;RSV Detection;Respiratory syncytial virus (RSV), direct fluorescent antibody (DFA) test;
Stability 24 hours at 2-8°C.
Turn around times see availability tables
Additional information REQUISITION: Microbiology (Viral-Rapid Test for RSV)
References 1. Product instructions. NOW¨ RSV Test Kit. Binax, Inc. Portland, ME. Rev. 3, 3/12/04.

2. Ohm-Smith, M.J, P.S. Nassos, and B.L. Haller. 2004. Evaluation of Binax NOW, BD Directigen, and BD Directigen EZ Assays for Detection of Respiratory Syncytial Virus. J Clin Microbiol 42:2996-99.
CPT coding 87807
Last Updated 4/10/2009 8:34:03 AM
Search Our Test Menu
UCSF home page UCSF home page About UCSF Search UCSF UCSF Medical Center