Differential Diagnosis for a Pregnant Patient with Shortness of Breath, Racing Heart, and Feeling Faint

Single Most Likely Diagnosis

• Pulmonary Embolism (PE): This condition is a leading cause of maternal mortality and is more common in pregnancy due to hypercoagulability. Symptoms such as shortness of breath, tachycardia, and fainting are classic presentations of a PE, making it the most likely diagnosis given the patient's symptoms.

Other Likely Diagnoses

• Preeclampsia with Severe Features: Preeclampsia can lead to cardiovascular complications, including heart failure and arrhythmias, which could explain the patient's symptoms. Although not as directly linked to the symptoms as PE, it's a common condition in pregnancy that can have severe consequences.
• Cardiomyopathy (Peripartum or Pre-existing): Pregnancy can unmask or exacerbate pre-existing heart conditions. Cardiomyopathy could lead to heart failure, causing shortness of breath, palpitations, and potentially syncope.
• Anemia: Severe anemia, which can be more common in pregnancy due to increased blood volume and demands, can lead to symptoms like shortness of breath, palpitations, and fainting due to decreased oxygen delivery to tissues.

Do Not Miss Diagnoses

• Aortic Dissection: Although rare, an aortic dissection is highly lethal and can present with sudden onset of shortness of breath and fainting. Pregnancy increases the risk due to hormonal effects on the aortic wall.
• Amniotic Fluid Embolism (AFE): AFE is a rare but highly lethal condition that can occur during pregnancy, labor, or postpartum. It presents suddenly with symptoms that can include shortness of breath, hypotension, and cardiac arrest.
• Placenta Previa or Abruption with Significant Blood Loss: Significant blood loss from these conditions can lead to hypovolemic shock, presenting with symptoms like fainting and tachycardia.

Rare Diagnoses

• Thyroid Storm: A rare but life-threatening condition in pregnant women with untreated or undertreated hyperthyroidism. Symptoms can include palpitations, shortness of breath, and potentially fainting.
• Pharmacologically Induced Conditions: Certain medications or substances can induce these symptoms, though this would be less common and highly dependent on the patient's medication history.
• Other Cardiac Conditions (e.g., Arrhythmias, Mitral Stenosis): While less common, other cardiac conditions can also present with these symptoms and should be considered, especially if there's a pre-existing condition or a family history of cardiac disease.