Fetal Cell Screen

Test Code

RHOG

Preferred Specimen

Lavender Top Tube, Plasma (EDTA), 3 ml

Patient Preparation
Maternal specimen collected after delivery of all products of conception. It is best to wait approximately 1 hour after delivery to allow fetal cells to mix with maternal circulation if present.

Testing is not required if patient is less than 20 weeks gestation. Testing can only be performed if the mother is Rh-negative and the infant is Rh-positive. If Rh is unknown, does not qualify, or either is weak D positive, Kleihauer-Betke testing must be performed instead.

Minimum Volume

2 ml

Instructions

Testing performed ASAP to permit administration of RhIG within 72 hours of delivery.

Transport Container

Lavender Top Tube

Transport Temperature

Room Temperature

Specimen Stability

Room Temp: Perform ASAP
Refrigerated: 2 days
Frozen: Unacceptable

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Do not use grossly hemolyzed samples for testing. Bacterial contamination may cause false positive results.

Methodology
A red blood cell suspension from a D-negative mother is incubated with reagent containing anti-D and then washed to remove unbound antibody. A weak suspension of D-positive red blood cells is added. The red blood cell mixture is centrifuged and examined microscopically for mixed-field agglutination.

Setup Schedule

Daily

Report Available

Daily

Reference Range

Not Applicable

Clinical Significance

Rho (D) Immune Globulin (RhIG) is used to prevent isoimmunization in the Rh negative individual exposed to Rh positive blood as a result of a fetomaternal hemorrhage. A full dose (300 μg) is sufficient to counteract the immunizing effects of 15mL of D-positive red cells; this corresponds to approximately 30 mL of fetal whole blood. The fetal bleed test is a screen to detect a feto-maternal hemorrhage of an amount greater than that covered by a standard dose of RhIG.

Performing Laboratory
Shady Grove Medical Center Only

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.