Given a KB test shows 18 fetal cells in 2000 adult cells, what is the calculated volume of fetal-maternal hemorrhage?

To determine the volume of fetal-maternal hemorrhage given the fetal cell count and the total number of adult cells, it’s important to understand the Kleihauer-Betke (KB) test, which is used to quantify the amount of fetal red blood cells (RBCs) in a maternal blood sample.

In this scenario, you've identified 18 fetal cells among 2000 adult cells. The formula to calculate the volume of fetal-maternal hemorrhage is as follows:

1. Calculate the percentage of fetal cells in the sample. This is done by dividing the number of fetal cells by the total number of cells (fetal plus adult) and then multiplying by 100:

[

\text{Percentage of fetal cells} = \left(\frac{18}{2000 + 18}\right) \times 100

]

2. This calculation gives you the proportion of fetal cells in the sample.

3. Next, you use a conversion factor to translate this percentage into a volume of hemorrhage. A common conversion used in clinical practice is that 1% of fetal cells correlates to approximately 0.5 mL of fetal blood.

4. Therefore, if you determine that