How many full doses of RhIg are indicated if a Kleihauer-Betke test identifies 40 fetal cells in 2000 maternal red cells?

How many full doses of RhIg are indicated if a Kleihauer-Betke test identifies 40 fetal cells in 2000 maternal red cells?

• A. 1
• B. 2
• C. 3
• D. 4

Answer: (D)

To determine the number of full doses of Rh immunoglobulin (RhIg) indicated based on the Kleihauer-Betke test results, it's essential to understand the calculation involved in assessing the amount of fetal red blood cells present in the maternal circulation. The Kleihauer-Betke test helps quantify the number of fetal red blood cells that have entered the maternal bloodstream, which is critical in guiding RhIg administration in Rh-negative mothers who have been sensitized. Typically, one full dose of RhIg (300 micrograms) is sufficient to neutralize about 30 mL of Rh-positive red blood cells or equivently 15 mL of fetal whole blood. In this scenario, the test shows 40 fetal cells among 2000 maternal red blood cells. To find the percentage of fetal cells, we calculate: Percentage of fetal cells = (Fetal cells / Total maternal red cells) x 100 = (40 / 2000) x 100 = 2%. To convert this percentage into the amount of fetal whole blood, we use the assumption that there are approximately 1,000,000 red blood cells in 1 mL of blood. Therefore, 2% of 2000 maternal cells equates to about

To determine the number of full doses of Rh immunoglobulin (RhIg) indicated based on the Kleihauer-Betke test results, it's essential to understand the calculation involved in assessing the amount of fetal red blood cells present in the maternal circulation.

The Kleihauer-Betke test helps quantify the number of fetal red blood cells that have entered the maternal bloodstream, which is critical in guiding RhIg administration in Rh-negative mothers who have been sensitized. Typically, one full dose of RhIg (300 micrograms) is sufficient to neutralize about 30 mL of Rh-positive red blood cells or equivently 15 mL of fetal whole blood.

In this scenario, the test shows 40 fetal cells among 2000 maternal red blood cells. To find the percentage of fetal cells, we calculate:

Percentage of fetal cells = (Fetal cells / Total maternal red cells) x 100 = (40 / 2000) x 100 = 2%.

To convert this percentage into the amount of fetal whole blood, we use the assumption that there are approximately 1,000,000 red blood cells in 1 mL of blood. Therefore, 2% of 2000 maternal cells equates to about