Maria, a 44-year-old woman with a history of paroxysmal nocturnal hemoglobinuria (PNH) and chronic alcohol use, presents with severe abdominal pain, abdominal distention, and shortness of breath that have progressively worsened over the past week. She reports episodes of vomiting but denies changes in bowel habits or stool color. She has a significant history of three hospital admissions for hepatic vein thrombosis in the last 12 months. She also takes daily oral contraceptives and mentions that her sister developed deep vein thrombosis at the age of 48 years. On examination, Maria has mild jaundice, a protuberant abdomen with a fluid wave, and right upper quadrant tenderness with hepatomegaly extending 7 cm below the costal margin. Prominent dilated veins are visible on her abdomen and back when standing, along with moderate ascites and bilateral pitting edema. Her vital signs show tachycardia and mild hypotension. Given her history of recurrent hepatic vein thrombosis, a thorough evaluation for underlying causes is initiated. What is the next best diagnostic evaluation in the management of this patient?
