You review a 35 year old lady who attends a GP-led A&E service, with a 6 hour history of dyspnoea, right-sided pleuritic chest pain and lower abdominal pain. On examination her heart sounds are normal, and chest is clear. She has no significant past medical history, and she is taking regular Ethinylestradiol 40 micrograms/Levonorgestrel 75 micrograms.
On examination, blood pressure is 116/84 mmHg, her heart rate is 76 beats per minute and her respiratory rate is 15 breaths per minute. Her subsequent ECG is unremarkable.
Based on the likely diagnosis, what is the most appropriate initial management option?