A 32 year old lady presents to the GP with a 3 day history of unilateral left sided calf swelling. She is 14 days postpartum, following an unremarkable pregnancy and normal vaginal delivery. On examination, she has a blood pressure of 112/72 mmHg, her heart rate is 72 beats per minute and her respiratory rate is 16 breaths per minute.
Based on the likely diagnosis, what is the most appropriate initial management option?