Differential Diagnosis for a 22-year-old at 23 weeks pregnancy with right-sided chest pain worsened by lying flat

• Single most likely diagnosis:
  • Pulmonary embolism is less likely but still a consideration, however, the most likely diagnosis in this context is pregnancy-related musculoskeletal pain or costochondritis, given the specific worsening of pain when lying flat, which could be related to the mechanical effects of pregnancy on the chest wall and musculoskeletal system.
• Other Likely diagnoses:
  • Pneumonia: Although less common, pneumonia can present with chest pain, especially if it involves the pleura. The pain worsening when lying flat could be due to increased pressure on the affected area.
  • Gastroesophageal reflux disease (GERD): Pregnancy can exacerbate GERD, leading to chest pain that worsens when lying down due to increased gastric pressure on the esophagus.
• Do Not Miss diagnoses:
  • Pulmonary embolism (PE): Although less likely given the specific characteristics of the pain, PE is a critical diagnosis to consider in any pregnant patient with chest pain due to the increased risk of thromboembolic events during pregnancy. Missing this diagnosis could be fatal.
  • Pneumothorax: Spontaneous pneumothorax can occur in pregnancy, and while the presentation might not always include typical symptoms, it's crucial to consider due to the potential for serious complications.
• Rare diagnoses:
  • Pericarditis: An inflammation of the pericardium that can cause chest pain, which might worsen with lying down. It's less common but should be considered if other symptoms like fever or a pericardial friction rub are present.
  • Spontaneous coronary artery dissection (SCAD): A rare cause of myocardial infarction that can occur in young women, especially during pregnancy. It presents with chest pain but would be an unusual cause of pain worsening specifically when lying flat.