Cardiac Tamponade Revealing a New Diagnosis of Malignancy

BACKGROUND: Hemodynamically significant pericardial effusions during pregnancy are rare but require urgent multidisciplinary intervention to determine necessity and timing of intervention. CASE SUMMARY: A 34-year-old nulliparous woman at 35 weeks and 4 days of gestation presented with acute chest pain and dyspnea. Evaluation revealed sinus tachycardia and a large pericardial effusion with clinical and echocardiographic signs of tamponade. Urgent pericardial drainage was performed, yielding 620 mL of sanguineous fluid. Cytology revealed malignant cells consistent with lung adenocarcinoma. The patient underwent a cesarean delivery and was ultimately diagnosed with stage IVB EML4-anaplastic lymphoma kinase-positive lung adenocarcinoma. DISCUSSION: Although pericardial effusions in pregnancy can be common, cardiac tamponade is rare and requires timely intervention and further evaluation. TAKE-HOME MESSAGES: Multidisciplinary collaboration is needed to determine the necessity and timing of intervention for pericardial effusions causing hemodynamic compromise in pregnancy. Sanguineous effusions should prompt evaluation for both aortic dissection and malignancy.