ChAdOx1 COVID-19 vaccine-induced thrombocytopenia syndrome.

Learning points for clinicians

COVID-19 vaccine-induced thrombosis with thrombocytopenia syndrome (TTS) has been reported as a very rare complication after the ChAdOx1 nCoV-19 (AstraZeneca) vaccination and usually manifesting as cerebral venous thrombosis or pulmonary artery embolism. In comparison with stroke and pulmonary embolism, TTS associated intra-abdominal thrombosis is less common. Early identification and timely treatment for TTS are required.

Introduction

COVID-19 vaccine remains critical to control the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), early recognition and management for COVID-19 vaccine-associated side effects are imperative. COVID-19 vaccine-induced thrombosis with thrombocytopenia syndrome (TTS) is one of the potential life-threatening complication. The pathophysiology of TTS is presumably the development of antibodies against platelet factor 4 (PF4), further resulting in platelet consumption, depletion and thrombus formation. We report a case of intra-abdominal thrombosis after the first-dose ChAdOx1 COVID-19 (AstraZeneca) vaccination.

Case report

A middle-aged woman complained of intermittent abdominal pain for 3 days and just received first-dose intramuscular injection of ChAdOx1 COVID-19 (AstraZeneca) vaccine 1 week previously. She did not take medicine and without active medical problems before. Her family history was non-contributory. Physical examination revealed mild tenderness over right upper abdominal quadrant and petechial rashes over bilateral legs. The urine routine test result was normal and the pregnancy test was negative. Polymerase chain reaction test for SARS-CoV-2 showed negative. Laboratory studies indicated decreased platelet count (32 000/ml3) and high D-Dimer level (>10 000; normal ≤ 500) ng/ml. Peripheral blood smears did not show schistocytes and screening tests for autoimmune antibodies were all negative. Coagulation tests results including antithrombin, protein C and protein S, prothrombin time and activated partial thromboplastin time levels were all in normal range. The kidney, ureter and bladder X-ray was unremarkable. Abdominal Doppler ultrasound indicated decreased flow in the right hepatic vein, and contrast-enhanced computed tomography (CT) showed the thrombus formation with occlusion in her right hepatic vein (Figure 1). During hospitalization, the serologic test of PF4 antibody was performed and the level (optical density: 0.621; normal ≤ 0.4) was high, which confirmed the diagnosis of COVID-19 vaccine-induced TTS. Medical treatment including intravenous immunoglobulin (IVIG, 1 g/kg daily for 2 days) and dexamethasone (40 mg for 4 days) were administrated. During the hospital stay, her abdominal pain subsided. After the 3-month follow-up, CT showed evident resolution of the thrombosis.

Figure 1.

Contrast-enhanced computed tomography demonstrated the thrombus formation with occlusion in her right hepatic vein.

Discussion

COVID-19 vaccine-induced TTS can be associated with thrombosis formation in portal vein, splanchnic vein and hepatic vein. TTS is caused by antibodies against PF4, triggering platelet activation and resulting in thrombosis formation with consumptive thrombocytopenia. This phenomenon is similar to type II heparin-induced thrombocytopenia. Medical treatment including IVIG, methylprednisolone, direct oral anticoagulants and even plasma exchange could be performed in some refractory cases of TTS.

Clinical signs and symptoms of the possibilities for COVID-19 vaccine-induced TTS should be considered including new-onset severe or persistent headache; double or blurred vision; chest, abdominal, back or legs pain; dyspnea; sensation changes or unilateral weakness; or legs swelling; and petechial skin rashes after the first-dose AstraZeneca vaccination. The complete blood cell count should be performed for any patient for whom there is a clinical suspicion of TTS. Early recognizing is more likely if physicians can inquire about the timing and type of COVID-19 vaccine as part of the regular history taking. Abdominal ultrasound is a valuable diagnostic tool, which helps to initially distinguish between hepatic vein thrombosis and other malignancy or hematologic disorders. Contrast-enhanced CT is a practical imaging study in patients with suspected intra-abdominal thrombosis-associated diseases. It plays an important role to define vascular abnormality and delineate morphological changes prior to surgical intervention. To date, the use of vaccines to prevent serious SARS-CoV-2 infections is considered the most favorable strategy for curbing the COVID-19 pandemic and is being vigorously pursued in the world. Physicians should be aware of COVID-19 vaccine-induced TTS, early diagnosis and optimal management can further prevent fatal complications and improve clinical outcomes.