A patient presents with fever, malaise, and a maculopapular rash that started on the face and spread to the trunk and extremities. Laboratory tests reveal leukopenia and thrombocytopenia. Which of the following is the most likely causative agent?

Correct Answer: C

Rationale: The clinical presentation of fever, malaise, maculopapular rash starting on the face and spreading to the trunk and extremities, along with leukopenia and thrombocytopenia, is highly suggestive of Rocky Mountain spotted fever (RMSF) caused by Rickettsia rickettsii. RMSF is a tick-borne illness transmitted by the American dog tick, Rocky Mountain wood tick, and brown dog tick. The constellation of symptoms described aligns well with the typical presentation of RMSF. Borrelia burgdorferi causes Lyme disease, which presents with erythema migrans but does not typically cause leukopenia or thrombocytopenia. Plasmodium falciparum is the causative agent of severe malaria and would present with symptoms such as cyclic fevers, anemia, and jaundice but not the described rash distribution.

Correct Answer: A

Rationale: In a pregnant woman presenting with severe abdominal pain, syncope, signs of hypovolemic shock, and gestational age of 6 weeks, the most likely cause is an ectopic pregnancy. An ectopic pregnancy occurs when a fertilized egg implants outside the uterus, commonly in the fallopian tube. As the pregnancy grows and the tube stretches, it can lead to rupture, causing severe abdominal pain, internal bleeding, and signs of shock. This is a life-threatening emergency that requires prompt diagnosis and management. It is important to consider ectopic pregnancy in any pregnant woman presenting with abdominal pain and signs of shock, especially in the first trimester.

Correct Answer: C

Rationale: Placenta previa is a condition in pregnancy where the placenta implants low in the uterus, partially or completely covering the cervix. This can lead to painless, bright red vaginal bleeding in the third trimester. However, in some cases, placenta previa can also present with sudden onset of severe lower abdominal pain and signs of shock, such as syncope, pallor, and abdominal distention due to concealed bleeding. In severe cases, the bleeding can be significant and life-threatening for both the mother and the baby. It is important to promptly diagnose and manage placenta previa to prevent complications.

Correct Answer: D

Rationale: Late decelerations on the fetal monitor tracing indicate a potential uteroplacental insufficiency, which could be caused by decreased oxygen supply to the fetus. One common cause of late decelerations is uterine hyperstimulation due to excessive use of oxytocin. By discontinuing the oxytocin infusion, the nurse can help alleviate the stress on the fetus and decrease the likelihood of further late decelerations. This action should be prioritized before other interventions such as changing the mother's position or administering oxygen. Immediate delivery may be necessary if the fetus continues to show signs of distress despite discontinuing the oxytocin infusion.

Correct Answer: B

Rationale: Magnesium sulfate is used to prevent eclampsia, but it can lead to toxicity if levels become too high. One common sign of magnesium toxicity is increased deep tendon reflexes, also known as hyperreflexia. This occurs because magnesium is a muscle relaxant, and elevated levels can lead to over-relaxation of muscles, causing an exaggerated reflex response. Other signs of magnesium toxicity include respiratory depression, decreased urine output, and cardiac arrest. Therefore, in a woman receiving intravenous magnesium sulfate during labor, an increase in deep tendon reflexes would indicate potential toxicity and require immediate intervention.