new case

A 50-year-old man presents with a 3-hour history of right arm pain. Two weeks ago, he was treated for superficial thrombophlebitis of the right cephalic and right saphenous veins. For the past two months, he has had significant back pain, which is being treated with NSAIDs. His temperature is 37.0C (98.6F), blood pressure is 140/80 mm Hg, pulse is 70/min, and respirations are 10/min. Physical examination shows a swollen, ruddy and warm right arm, but is otherwise unremarkable. Cervical and chest x-ray films show no abnormalities. Laboratory studies show:

Hct
50%
Platelets
120,000/cmm
WBC
9,600/cmm
Neutrophils
60%
Eosinophils
2%
Basophils
0%
Lymphocytes
31%
Monocytes
7%
PT
25 sec
PTT
39 sec
Fibrinogen
300 mg/dL
Fibrin split products
positive
Which of the following is the most appropriate next step in management?
A
Protein C, S and antithrombin III levels
B
Perfusion scintigraphy of the lungs
C.
Venography of right brachial, axillary and subclavian veins
D.
CT of the chest, abdomen and pelvis
E.
CT of the thoracic outlet