A 32-year-old woman, who is 34 weeks pregnant (gravida 1, para 0), is brought to the emerg… — USMLE Step 2 CK

A $32$ -year-old woman, who is $34$ weeks pregnant (gravida 1, para 0), is brought to the emergency department by ambulance after a high-speed motor vehicle collision. She was the restrained driver and struck the steering wheel. On arrival, she is restless, confused, and diaphoretic. Her medical history is notable for mild persistent asthma. Temperature is $37.0^\circ\text{C}$ , blood pressure is $76/42$ mmHg, heart rate is $138/\text{min}$ , and respiratory rate is $28/\text{min}$ . Pulse oximetry is $91\%$ on room air. Primary survey reveals a patent airway. The jugular veins are markedly distended. Auscultation of the lungs reveals diffuse expiratory wheezing. Heart sounds are distant and muffled. The gravid uterus is non-tender. A bedside Focused Assessment with Sonography for Trauma (FAST) reveals an anechoic fluid stripe surrounding the heart with inward collapse of the right ventricular free wall during diastole; there is no free intra-abdominal fluid. Continuous fetal monitoring shows a baseline heart rate of $155/\text{min}$ with minimal variability and recurrent late decelerations. Which of the following is the most appropriate next step in management?

Perform immediate ultrasound-guided pericardiocentesisAnswer
B
Obtain a computed tomography angiogram of the chest and abdomen
C
Administer intravenous methylprednisolone and nebulized albuterol
D
Place the patient in the left lateral decubitus position and administer intravenous crystalloids
E
Proceed to the operating room for an emergent cesarean delivery

Answer

The most appropriate next step in management is to perform immediate ultrasound-guided pericardiocentesis.

This pregnant trauma patient presents with classic signs of acute cardiac tamponade: hypotension, jugular venous distension, and muffled heart sounds (Beck's triad). The diagnosis is confirmed by the FAST exam showing a pericardial effusion with right ventricular diastolic collapse. Cardiac tamponade causes obstructive shock, severely reducing cardiac output. This resulting hypoperfusion leads to secondary complications, including back-pressure pulmonary edema (presenting as wheezing or 'cardiac asthma') and uteroplacental insufficiency (causing late fetal decelerations). The most critical and immediate next step is to relieve the pericardial pressure. Ultrasound-guided pericardiocentesis is the appropriate life-saving temporizing measure to restore maternal cardiac output, which will concomitantly improve uterine perfusion and relieve fetal distress.

Step-by-Step Solution

Analyze the patient's hemodynamic status and physical exam findings.

The patient is in profound shock (blood pressure

76/42

mmHg) with Beck's triad: hypotension, jugular venous distension, and muffled heart sounds.

Identifying the type of shock is critical in trauma algorithms.

Interpret the bedside imaging (FAST exam).

The FAST exam confirms pericardial fluid with right ventricular diastolic collapse, establishing the diagnosis of acute cardiac tamponade.

Echocardiographic evidence of chamber collapse confirms that the effusion is causing obstructive physiology.

Evaluate the secondary symptoms (wheezing and fetal decelerations) in the context of the primary diagnosis.

The wheezing is 'cardiac asthma' resulting from back-pressure into the pulmonary vasculature, and the late fetal decelerations represent uteroplacental insufficiency driven by maternal obstructive shock.

Understanding that these are secondary manifestations prevents anchoring on incorrect alternative diagnoses like an asthma exacerbation or isolated obstetric emergencies.

Determine the definitive immediate intervention.

The obstructive shock must be relieved immediately via ultrasound-guided pericardiocentesis (or a surgical pericardial window) to restore cardiac output and save both the mother and the fetus.

Maternal resuscitation is the most effective way to reverse fetal distress in this scenario.

Key Concept

Acute cardiac tamponade in trauma presents with obstructive shock and requires immediate decompression via pericardiocentesis or pericardial window; secondary symptoms like wheezing or fetal distress will improve once maternal hemodynamics are restored.

Estimated Time:2m 0s

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