单选题 After determining that a pregnant client is Rh-negative, the physician orders an indirect Coombs'test. What's the purpose of performing this test on a pregnant client?

A. To determine the fetal blood Rh factor.
B. To determine the maternal blood Rh factor.
C. To detect maternal antibodies against fetal Rh-positive factor.
D. To detect maternal antibodies against fetal Rh-negative factor.

【正确答案】 C

【答案解析】The indirect Coombs'test measures the level of antibodies against fetal Rh- positive factor in maternal blood. Although this test may determine the fetal blood Rh factor, the physician doesn't order it primarily for this purpose. The maternal blood Rh factor is determined be{ore the indirect Coombs'test is done. No maternal antibodies against fetal Rh-negative factor exist.