A 35-year-old woman presents to the emergency department reporting a chronic history of intermittent dark-colored urine, particularly noticeable in the mornings, and persistent generalized fatigue. Over the past 48 hours, she has experienced a sharp increase in shortness of breath with minimal exertion, diffuse abdominal discomfort, and noticed her urine has become consistently reddish-brown. She also reports a recent episode of severe headache and transient visual disturbances. On examination, she appears markedly pale with mild icterus. Vital signs include temperature 37.2 0C (99.0 0F), blood pressure 95/60 mm Hg, pulse rate 118/min, and respiratory rate 20/min. Oxygen saturation is 97% on room air. Petechiae are noted on her lower extremities. Abdominal palpation reveals mild tenderness in the epigastrium and left upper quadrant without guarding. There is no hepatosplenomegaly. Neurological examination is non-focal. The peripheral blood smear shows normocytic, normochromic erythrocytes without spherocytes, schistocytes, agglutinated erythrocytes, or immature appearing leukocytes. Given this presentation, what is the most probable diagnosis and the critical initial management consideration?

A 27-year-old woman, known to have a chronic hemolytic anemia, presents to her hematology clinic for routine follow-up. She reports an increase in her typical intermittent dark urine episodes over the past month, often noticeable in the mornings. She also mentions experiencing persistent left-sided headache and occasional transient right-sided blurry vision, which she attributes to her "anemia." Her medical history includes multiple episodes of unexplained abdominal pain and a prior hospitalization for a deep vein thrombosis in her leg two years ago, which was managed conservatively. Her family history is notable for a sibling with a benign hematologic condition. On physical examination, she is mildly jaundiced with a scleral icterus. There is mild right upper quadrant tenderness, and the liver edge is palpable 4 cm below the right costal margin, consistent with prior examinations. Her spleen is not palpable. Labs from her visit are reviewed. A peripheral smear continues to show polychromasia. A recent abdominal ultrasound showed persistent decreased flow in the right hepatic vein and mild hepatomegaly. Given her escalating symptoms and laboratory findings, which management strategy is most appropriate for her current presentation, and what serious complication should be closely monitored?

A 25-year-old woman presents to the emergency department with acute onset of profound fatigue, shortness of breath, and dark-colored urine, especially noticeable in the mornings. She reports a recent history of recurrent abdominal discomfort and easy bruising, dismissing them as stress-related from her demanding work as a software engineer. Two days prior, she had attended a demanding hackathon, which involved long hours and minimal rest. She denies any significant past medical history or family history of bleeding disorders. Her vital signs are: Temperature 37.50C, blood pressure 95/60 mmHg, heart rate 118/min, and respiratory rate 26/min. Physical examination reveals marked conjunctival pallor, mild scleral icterus, and diffuse petechiae on her lower extremities. Auscultation of the abdomen reveals mild splenomegaly. Peripheral blood smear reveals normocytic, normochromic cells with polychromasia. What is the most likely diagnosis and the immediate therapeutic intervention required?