Massive Pulmonary Embolism in Early Pregnancy Presenting as Syncope and Seizure: A Diagnostic Pitfall

Pulmonary embolism (PE) is a life-threatening condition with highly variable presentations, and atypical manifestations such as syncope or seizure can obscure timely diagnoses, particularly in young and otherwise healthy individuals. This case report focuses on a 26-year-old female in early pregnancy who presented with a transient loss of consciousness and seizure-like activity and was ultimately found to have a massive saddle PE. The case emphasizes the diagnostic challenges and the critical role of rapid, multidisciplinary intervention in such high-risk scenarios. The patient was previously healthy and reported mild lower abdominal discomfort. On presentation, she was hypotensive and tachycardic and had a superficial forearm burn sustained during the event. Laboratory evaluation revealed hypokalemia, elevated lactate, raised creatine kinase, and troponin. Positive β-hCG prompted a pelvic ultrasound, suggesting a possible early gestational sac, with gynecology attributing the findings to an implantation bleed. Neurological and cardiac evaluations excluded seizure disorder and myocardial ischemia. Despite fluid resuscitation, the patient remained hemodynamically unstable. An electrocardiogram (ECG) demonstrated an S1Q3T3 pattern, and bedside echocardiography revealed right ventricular dilation. Computed tomography (CT) pulmonary angiography confirmed extensive bilateral pulmonary emboli, including a saddle embolus. She underwent mechanical thrombectomy complicated by cardiac arrest, requiring cardiopulmonary resuscitation (CPR) and intravenous (IV) alteplase administration, followed by intensive care unit (ICU) care. A right atrial thrombus was noted and managed with anticoagulation. Gynecological assessment revealed a missed abortion. The patient stabilized with supportive care, anticoagulation, and monitoring and was successfully extubated and discharged after 10 days on rivaroxaban, with follow-up arranged with cardiology, pulmonology, and internal medicine. This case underscores the importance of maintaining a high index of suspicion for PE in atypical presentations, particularly in pregnancy, and highlights the critical role of prompt imaging, multidisciplinary collaboration, and timely intervention in improving outcomes for high-risk patients.