A 28-year-old woman, gravida 1, para 0, at 14 weeks gestation presents to the emergency de… — USMLE Step 2 CK

A 28-year-old woman, gravida 1, para 0, at 14 weeks gestation presents to the emergency department with a 3-day history of shortness of breath, sharp right-sided chest pain that worsens with deep inspiration, and low-grade fever. She was diagnosed with systemic lupus erythematosus (SLE) 4 years ago and is currently taking hydroxychloroquine. Her temperature is $37.9^\circ \text{C}$ ( $100.2^\circ \text{F}$ ), blood pressure is $122/76 \text{ mm Hg}$ , pulse is $112/\text{min}$ , and respirations are $24/\text{min}$ . Pulse oximetry is $96\%$ on room air.

Physical examination reveals an erythematous rash over the cheeks and nasal bridge, as well as swelling, erythema, and tenderness in the metacarpophalangeal joints bilaterally. Lung auscultation reveals decreased breath sounds and dullness to percussion at the right lung base. Jugular venous pressure is $6 \text{ cm H}_2\text{O}$ .

Laboratory studies show:
- Leukocytes: $4,200/\text{mm}^3$
- Hemoglobin: $10.5 \text{ g/dL}$
- Platelets: $130,000/\text{mm}^3$
- Creatinine: $0.7 \text{ mg/dL}$
- Urinalysis: Normal

A chest radiograph with abdominal shielding shows a small right-sided pleural effusion without focal airspace opacities. A ventilation-perfusion scan indicates a low probability of pulmonary embolism. An echocardiogram shows normal ventricular function and no pericardial effusion.

Which of the following is the most appropriate next step in management?

Initiation of oral prednisoneAnswer
B
Administration of intravenous furosemide
C
Administration of intravenous piperacillin-tazobactam
D
Reassurance and routine prenatal follow-up
E
Measurement of antinuclear antibody (ANA) titer

Answer

Initiation of oral prednisone

The correct response is the initiation of oral prednisone. This patient is experiencing an acute systemic lupus erythematosus (SLE) flare manifesting as serositis (pleuritis with a pleural effusion), arthritis, and a malar rash. The acute onset of pleuritic chest pain and a unilateral exudative-appearing pleural effusion in a patient with SLE strongly suggests lupus pleuritis, especially when pulmonary embolism has been excluded (via a normal ventilation-perfusion scan) and there are no signs of pneumonia. Mild to moderate SLE flares during pregnancy are best managed with systemic glucocorticoids. Prednisone is specifically favored because it is extensively converted by the placental enzyme

11

-beta-hydroxysteroid dehydrogenase 2 into an inactive metabolite, thereby minimizing fetal exposure and toxicity.

Step-by-Step Solution

Analyze the patient's clinical presentation.

The patient has pleuritic chest pain, dyspnea, fever, a unilateral pleural effusion, malar rash, and active arthritis in the setting of established SLE.

To synthesize the clinical signs and symptoms into a unifying diagnosis.

Formulate the most likely diagnosis.

The combination of findings indicates an acute SLE flare, specifically manifesting as serositis (pleuritis and pleural effusion).

Pulmonary embolism and heart failure have been ruled out via imaging, and the concomitant joint and skin findings point directly to increased autoimmune activity.

Determine the appropriate therapy for the condition in a pregnant patient.

Systemic glucocorticoids (e.g., oral prednisone) are indicated. Prednisone is preferred during pregnancy because it is extensively metabolized by placental enzymes, minimizing fetal exposure.

To rapidly control the harmful autoimmune inflammation while ensuring fetal safety.

Key Concept

An acute SLE flare manifesting as serositis (pleuritis and pleural effusion) in a pregnant patient should be treated promptly with systemic glucocorticoids like prednisone, which are safe and effective during pregnancy.

Question

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Topics

More questions from this topic