Edema Mechanisms

A 52-year-old man with a 10-year history of cirrhosis due to hepatitis B presents with progressive abdominal distension and bilateral ankle swelling over 2 weeks. On examination: blood pressure 110/70 mmHg, heart rate 88/min, JVP normal, abdomen tense with shifting dullness, and bilateral pitting ankle edema. Liver is firm and nodular. Laboratory tests show: serum albumin 2.4 g/dL, total bilirubin 3.2 mg/dL, INR 1.8, and portal vein pressure estimated at 18 mmHg (normal <12). Urine sodium is 5 mEq/L. What is the PRIMARY mechanism of edema formation in this patient?

A 38-year-old woman from rural Maharashtra presents with progressive swelling of both legs over 3 months. She reports a history of recurrent diarrhea for the past 6 months and poor dietary intake. On examination, she has pitting edema in both lower limbs, and her abdomen shows mild ascites. Laboratory investigations reveal: serum albumin 2.1 g/dL (normal 3.5–5.5), total protein 4.8 g/dL, hemoglobin 8.2 g/dL, and urine dipstick is negative for protein. What is the primary mechanism responsible for the edema in this patient?

Which of the following mechanisms is responsible for edema formation in nephrotic syndrome?