After performing an acid elution stain, if 30 of 2,000 cells appear to contain fetal hemoglobin, how many vials of Rh immune globulin would be indicated if the estimated volume exceeds 20 mL?

To determine the correct answer, it's important to understand the implications of the acid elution stain results to assess the amount of Rh immune globulin needed based on the presence of fetal hemoglobin.

In this scenario, the number of cells that show fetal hemoglobin (30 out of 2,000) indicates that there may be a significant amount of fetal blood present in the maternal circulation. When fetal blood is present, especially in amounts exceeding the threshold volume of 20 mL, Rh immune globulin is administered to prevent Rh immunization in Rh-negative mothers.

The Rosette test can be used to quantify the volume of fetal blood by calculating the percentage of affected cells. In this case, if 30 cells out of 2,000 showed fetal hemoglobin, we can calculate the percentage:

• Percentage of fetal hemoglobin cells = (30 / 2000) * 100 = 1.5%

To convert this percentage to an estimated volume of fetal blood, the general formula used is to estimate that 1% of fetal blood corresponds to approximately 30 mL in maternal circulation. Therefore, if 1.5% of fetal blood cells are present, we would estimate that:

• Estimated fetal blood volume = 1.5