Match each clinical presentation of a pregnant patient with the most appropriate routine screening test or intervention indicated at that specific gestational age.
- A primigravida at 16 weeks gestation who missed first-trimester evaluation, seeking screening for fetal aneuploidy and neural tube defects.Measurement of maternal serum alpha-fetoprotein, human chorionic gonadotropin, estriol, and inhibin A
- A pregnant patient at 26 weeks gestation without preexisting diabetes, presenting for a routine second-trimester follow-up visit.Administration of a 50-g oral glucose load followed by a 1-hour venous glucose determination
- An Rh(D)-negative pregnant woman at 28 weeks gestation whose current indirect Coombs test is negative.Intramuscular injection of prophylactic anti-D immune globulin
- A multiparous woman at 36 weeks gestation with an uncomplicated pregnancy and no history of delivering an infant with invasive bacterial disease.Collection of a combined vaginal-rectal swab for culture
Answer
The correct matches align gestational milestones with ACOG guidelines: 16 weeks requires the quadruple marker screen; 26 weeks requires the 50-g oral glucose challenge test; 28 weeks in an Rh(D)-negative patient requires anti-D immune globulin; and 36 weeks requires Group B Streptococcus rectovaginal screening.
Each routine prenatal intervention must be precisely timed to maximize clinical utility and accuracy. The quadruple marker screen is most accurate between 15 and 22 weeks. Universal screening for gestational diabetes with a 50-g glucose load is indicated at 24 to 28 weeks when insulin resistance begins to peak. Rh(D)-negative, unsensitized women require prophylactic anti-D immune globulin at 28 weeks to prevent alloimmunization for the remainder of the pregnancy. Group B Streptococcus screening is recommended near term (36-37 weeks) to ensure the result is valid at the time of delivery.
Step-by-Step Solution
Key Concept
Routine prenatal care involves specific screening modalities and prophylactic interventions that are strictly tied to gestational age milestones to optimize clinical outcomes.