Final answer:
The most appropriate next step for managing a pregnant woman at 28 weeks gestation with signs suggestive of chorioamnionitis is (D) labor induction to prevent complications to both mother and fetus.
Step-by-step explanation:
A 20-year-old G2P1 woman at 28 weeks gestation presenting to labor and delivery with contractions every four minutes, a slightly elevated temperature (100.5°F or 38.0°C), tachycardia (heart rate of 120), a tender uterine fundus, and a cervix dilated to 1 cm and 50% effaced requires careful assessment and management. The fetal heart tones are in the 150s with a category I tracing, indicating a reassuring fetal status at this time. However, her elevated white blood cell count (WBC) of 18,000/mcL and the tender uterine fundus could suggest an underlying infection, such as chorioamnionitis, which is a bacterial infection of the amniotic fluid and fetal membranes.
The most appropriate next step in her management would be labor induction. Inducing labor in the setting of potential intra-amniotic infection is crucial to prevent any complications to both the mother and the fetus. The option of observation, tocolysis, or contraction stress test would not be appropriate in the presence of signs of potential infection and preterm labor. Cesarean section may be considered if there are contraindications to vaginal delivery or if urgent delivery is deemed necessary due to maternal or fetal status.