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HelpTest Code GBSNAT Group B Strep Screen, Nucleic Acid Test
Useful For
Screening of Group B streptococci carriage in pregnant females.
Synonyms/Keywords
GBS Screen, GBSNAT-RFX
Specimen Requirements
| Specimen Type | Preferred Container/Tube | Acceptable Container/Tube | Specimen Volume | Specimen Minimum Volume (allows for 1 repeat) |
Pediatric Minimum Volume (no repeat) |
|---|---|---|---|---|---|
| Vaginal introitus and/or anorectum | ESwab™ | Other Amies medium based swab | 1 swab | 1 swab | N/A |
Collection/Processing Instructions
A swab specimen should be collected first from the lower vagina and then from the rectum without use of a speculum.
- Submit one ESwab™ collection device
- Other Amies medium swab types are acceptable: collect one swab
See eSwab collection video for more information
'ESwab' is a trademark of Copan Diagnostics.
For more information on Specimen Collection Media/Swab, see Specimen Transport Pictorial.
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
|
Swabs |
Room Temperature | < 4 hours |
| Refrigerated | 48 hours |
Rejection Criteria
| Cervical, perianal, perirectal and perineal swabs |
| Dry swabs |
| Leaking specimens |
| Specimens older than 48 hours |
Test Information
This is a qualitative PCR assay that incorporates the use of LIM selective enrichment broth to detect Group B streptococci. Results will be reported as Positive, Negative or Indeterminate.
The American Society for Microbiology has published guidelines for optimal practices for screening for Group B streptococcal (GBS) carriers. These guidelines recommend universal prenatal screening for vaginal and rectal GBS colonization of all pregnant women at 36-37 weeks unless intrapartum GBS prophylaxis is already recommended due to identified risk factors.
For penicillin allergic patients, screening can be ordered with automatic reflex to susceptibility testing (Test Code: GBSNAT-RFX).
Susceptibility results will be available 48-72 hours after positive GBSNAT result. If no Group B Streptococci is isolated on reflex culture the report will indicate "A positive test result obtained by PCR testing (GBSNAT) does not indicate the presence of viable organism; this testing is more sensitive than culture".
(ASM Guidelines for the Detection and Identification of Group B Streptococcus July 29, 2021)
Reference Range Information
| Performing Location | Reference Range |
|---|---|
| All Perfoming Sites | Strep Group B negative |
Marshfield Labs Performing Department
Marshfield Labs Microbiology
Performing Information
| Performing Location | Day(s) Test Performed | Analytical Time | Methodology/Instrumentation |
|---|---|---|---|
| Marshfield | Monday through Sunday | 3 days | LIM broth enrichment, Group B Streptococcus Detectionby Real Time PCR |
CPT Codes
| CPT | Modifier (if needed) |
Quantity | Description | Comments |
|---|---|---|---|---|
| 87653 | Streptococcus, group B, amplified probe technique |
|
||
| 87077 or 87147 |
Organism identification from Culture | as needed |
||
| 87186 or 87184 |
Susceptibility testing | as needed |
Outreach CPT Codes
| CPT | Modifier (if needed) |
Quantity | Description | Comments |
|---|---|---|---|---|
| 87653 | Streptococcus, group B, amplified probe technique |
|
||
|
87077 or 87147 |
Organism identification from Culture | as needed | ||
|
87186 or 87184 |
Susceptibility testing | as needed |
Ordering Applications
| Ordering Application | Description |
|---|---|
| Cerner | Group B Strep Screen by Nucleic Acid Test |