The Rosette Test is a screening test used to detect the presence of Rh positive cells in an Rh negative mother. This test is done on postpartum mothers who gave birth to an Rh positive baby. When Rh positive cells are present in the circulation of an Rh negative mother, rosette or clumps will be formed. Formation of clumps are noted when an excessive hemorrhage of fetal structures from an Rh positive infant occurs.
Purpose of Performing the Test
To assess the presence of Rh positive cells in the circulation of an Rh Negative mothers.
Principle of Rosette Test
The red blood cells of an Rh negative mother are incubated with anti-D. If positive cells are present in the blood, the anti-D sensitizes with the positive cells and enzyme-treated cDE indicator cells are added and will bind to any anti-D-sensitized Rh positive cells and will then form the rosettes or clumps. The clumps will be visible in microscopic examination.
Who will be the subjects of the Rosette test?
This test is only suitable for Rh negative mothers who gave birth 72 hours to an Rh Positive infant. The test is not indicated and suitable for other patients.
Rosette Test should not be done in the following circumstances:
- Neonates who have a weak D expression
- Mothers who have a weak D expression
Difference between Rosette Test and Kleihauer-Betke Test
The Rosette test will determine the presence of Rh positive cells in an Rh negative mother. Kleihauer-Betke test also does the same. However, it not only detects the presence of Rh positive cells but at the same time determines the volume of the fetomaternal hemorrhage. Kleihauer-betke test is a quantitative test is usually required when Rosette test is positive.
- All requests made must contain the physician’s name and ID number.
- The specimen must be labeled with the patient’s full name and date of collection.
- Volume of the blood sample needed is about 3 to 5 ml.
- After the blood sample is drawn, the nurse should apply pressure to the puncture site until the bleeding stops. This is to reduce bruising and bandage is applied to the site.
- The woman may resume normal activities after the procedure.