A 31-year-old woman comes to the physician for evaluation of worsening pain, swelling, and erythema in her left leg for the past 4 hours. She returned from a trip to Taiwan to celebrate her sister's wedding 2 days ago. She has no history of serious illness. She is sexually active with one male partner and uses a combined oral contraceptive pill. She does not smoke cigarettes, drink alcohol, or use illicit drugs. Her only other medication is a multivitamin. Her temperature is 37.2°C (99°F), pulse is 67/min, respirations are 16/min, and blood pressure is 90/60 mm Hg. Examination shows swelling in her left calf and pain behind her left knee when she is asked to dorsiflex her left foot. Laboratory results show elevated D-dimer. Which of the following is the most likely cause of this patient's clinical presentation?

Question

Quizplus · Accepted Answer

Eductional Objective: Estrogen found within COCs decreases protein S levels. Since protein S is an essential cofactor for protein C, which inactivates procoagulant factors Va and VIIIa, reduction of protein S results in an increased risk for thrombus formation and the development of DVTs.

A 31-Year-Old Woman Comes to the Physician for Evaluation of Worsening