BILATERAL PULMONARY EMBOLISM; ACUTE THROMBUS WITHIN THE LEFT COMMON ILIAC VEIN; ACUTE THROMBUS WITHIN LEFT COMMON ILIAC VEIN EXTENDING INTO INFERIOR VENA CAVA; MAY-THURNER SYNDROME; This spontaneous report was received from literature: This report concerned a 44-year-old female of unspecified race and ethnicity. The objective of this study was to describe the case of acute thromboembolism after covid-19 vaccination in the setting of may- Thurner syndrome. The patient's weight, height, and medical history were not reported. The patient received covid-19 vaccine ad26.cov2.s (suspension for injection, route of admin, and batch number, expiry were not reported) dose, start therapy date were not reported, 1 total administered on unspecified date for covid-19 prophylaxis. The batch number was not reported. Per procedure, no follow-up will be requested for this case. No concomitant medications were reported.  On an unspecified date, five days after vaccination patient experienced fever, chest pain and left lower extremity (LLE) pain and swelling. The patient vital signs were within normal limit when visited emergency department (ED). The patient initial lab work was normal, complete blood count was normal, but D-dimer was elevated to 3571 ng/ml, initial electrocardiogram (EKG) showed sinus tachycardia at 128 bpm, chest X-ray showed hyperaerated lungs, Ultrasound Doppler of LLE showed no evidence of DVT (deep vein thrombosis), CTA (computed tomography angiography) chest identified numerous filling defects in the bilateral pulmonary arterial tree including both upper lobes and both lower lobes. The patient platelets were normal at baseline. The patient was started on therapeutic enoxaparin and was admitted (on unspecified date) for bilateral pulmonary embolism (acute thromboembolism). Echocardiogram showed normal EF (Ejection fraction) without RV (Right ventricular) strain. The patient underwent CT (computed tomography) abdomen and pelvis venogram to assess for iliocaval DVT in the setting of persistent leg swelling and discoloration which showed May-Thurner syndrome with compression of left common iliac vein by the right common Iliac artery. There was an acute thrombus within the left common iliac vein extending into the IVC (inferior vena cava). The patient underwent mechanical thrombectomy and stenting of the common external iliac vein. The patient was transitioned from enoxaparin to apixaban and was discharged in stable conditioned. Number of days of hospitalization were 06. The action taken with covid-19 vaccine ad26.cov2.s was not applicable. The outcome of the may-thurner syndrome, bilateral pulmonary embolism, acute thrombus within the left common iliac vein and acute thrombus within left common iliac vein extending into inferior vena cava was not reported. The authors concluded that are other rare causes of DVT, like May-Thurner Syndrome, in which an anatomical variant of the right common iliac artery compresses the left common iliac vein, vaccine against COVID-19 is associated with thromboembolism which can occur at different sites, including cerebral, splanchnic and ophthalmic veins. This report was serious (Hospitalization Caused / Prolonged).; Sender's Comments: V0: 20230819989-bilateral pulmonary embolism, acute thrombus within the left common iliac vein and acute thrombus within the left common iliac vein extending into the inferior vena cava. The case causality is considered INCONSISTENT. Rationale: concurrent condition of May-Thurner Syndrome (confounding factor ) provides more plausible explanation than role of vaccine 20230819989-May-Thurner Syndrome. The event has a compatible/suggestive temporal relationship, is unlabeled, and has unknown scientific plausibility. There are other factors more likely to be associated with the event. Specifically: NATURE OF EVENT- May-Thurner syndrome in which an anatomical variant of the right common iliac artery compresses the left common iliac vein. Therefore, this event is considered inconsistent with vaccine administration.