Questionnaire/history:

New onset of severe headache, which is getting worse and does not respond to simple analgesics?

Headache suggestive of raised ICP or with neurological symptoms?

Unusual headache which is worse when supine or bending?

Blurred vision?

Nausea?

Vomiting?

Difficulties with speech?

Weakness?

Drowsiness?

Seizures?

New and unexplained petechiae or bleeding?

Symptoms or signs suggestive of pulmonary embolism, deep venous thrombosis or persistent abdominal pain suggesting possible splanchnic vein thrombosis?

Past medical history?

Current medication? Drug allergies?

Investigations:

Full blood cell count

D-dimer (in secondary care)

Fibrinogen (in secondary care)

Management:

Acutely unwell? - If yes, referred to the emergency department immediately?

No acutely unwell and same-day test results can be obtained?

- If yes, full blood cell count (FBC) and referred to emergency department immediately if it shows thrombocytopenia?

Patient not acutely unwell and FBC normal?

- If yes, reassured that VITT unlikely, to think of alternative diagnosis and managed symptomatically?

High clinical suspicion of VITT remains? - If yes, repeated FBC in 2 to 3 days

Resource(s): NICE: COVID-19 rapid guideline: vaccine-induced thrombocytopenia and thrombosis