Introduction Phlegmasia cerula dolens (PCD) is an uncommon complication of deep vein thrombosis (DVT), and involvement in the upper extremities is rare. We report a case in which color duplex ultrasound (CDU) was used to diagnose PCD in a patient with extensive upper extremity DVT. Patient A 57-year-old woman underwent an open lung biopsy. On the first postoperative day, she had right hand and forearm pain, edema, and cyanosis. Findings CDU revealedacute DVT in the right radial, ulnar, and brachial veins and extensive thrombosis of the right cephalic and basilic veins. Arterial signals recorded from the ipsilateral arteries were remarkable for pandiastolic flow reversal (PDFR). In contrast, arterial signals from the contralateral arm had a normal, triphasic pattern. Arteriography revealed patent arteries to the wrist and no flow present in the right hand. Conclusions This report demonstrates the sensitivity of CDU to arterial compromise associated with PCD in a case of upper extremity DVT. Vascular technologists should consider including arterial Doppler signals in their venous duplex protocols in cases of extensive deep and superficial vein thrombosis.