Sites of Fluid Accumulation Beyond the Lungs
Fluid accumulates in the peripheral tissues (lower extremities and sacrum), abdomen (ascites), pericardial sac, pleural space, and liver (hepatic congestion) in patients with heart failure, liver disease, or kidney disease. 1
Peripheral Edema (Lower Extremities and Sacrum)
Lower extremity edema is the most common site of fluid accumulation outside the lungs, typically associated with elevated right atrial pressure from left-sided heart failure. 1
Sacral edema develops in bedridden patients as fluid redistributes to dependent areas during bed rest and is commonly missed on casual examination. 1
Both the sacrum and lower limbs must be examined together, as apparent improvement in leg edema without weight loss suggests fluid redistribution rather than true resolution. 1
Peripheral edema results from increased capillary hydrostatic pressure (cardiac, cirrhosis with portal hypertension, renal failure) or decreased oncotic pressure (hypoalbuminemia from liver disease, nephrotic syndrome, or malnutrition). 1, 2
Ascites (Abdominal Fluid)
Ascites occurs primarily in hepatic cirrhosis with portal hypertension and in advanced heart failure with elevated right-sided pressures. 1, 2
In cirrhotic patients, aggressive fluid resuscitation worsens gut edema and increases intra-abdominal pressure, potentially leading to abdominal compartment syndrome. 2
Nephrotic syndrome causes ascites through massive proteinuria leading to hypoalbuminemia and decreased plasma oncotic pressure. 2
Pericardial Effusion
Pericardial fluid accumulation is common and associated with infection, malignancy, trauma, myocardial disease, and post-operative states. 1
Large pericardial effusions (>50 mL) usually indicate significant disease and warrant reporting, though volume estimation on CT is subject to variation based on patient body habitus. 1
In renal failure patients, pericardial effusions occur in up to 20% of cases, presenting as either uremic pericarditis (before dialysis) or dialysis-associated pericarditis (from inadequate dialysis or fluid overload). 1
Pleural Effusion
Pleural effusions develop when hydrostatic pressure, colloid osmotic pressure, filtration coefficient, or lymphatic function are altered. 3
Congestive heart failure, pancreatitis, neoplasia, hypoalbuminemia, and pulmonary thromboembolism can evoke pleural effusions by disrupting normal fluid transport mechanisms. 3
A large, heterogeneous mediastinal lesion with pleural effusion suggests aggressive thymic epithelial neoplasm. 1
Hepatic Congestion
Hepatic congestion manifests through distended jugular veins, hepatomegaly, and positive hepatojugular reflux in the context of chronic right-sided heart failure or acute decompensated heart failure. 4
Elevated gamma-glutamyltransferase (GGT) is the most common and earliest laboratory abnormality, present in >85% of cases. 4
Doppler ultrasonography or multiphase CT/MRI shows dilated hepatic veins, hepatomegaly, and heterogeneous parenchymal enhancement pattern. 4
Clinical Assessment Priorities
Jugular venous pressure (JVP) reflects right atrial pressure and usually indicates elevated pulmonary capillary wedge pressure in heart failure patients. 1
An elevated JVP improves the specificity of peripheral edema as a sign of true congestion rather than non-cardiac causes (venous insufficiency, hypoalbuminemia). 1
Daily body weight changes most likely reflect volume status, with acute changes being a reasonable marker of fluid balance when measured consistently (same time, post-void, prior to eating, same clothing). 1
Important Caveat: Distinguishing from Lymphedema
Before attributing edema to cardiac, hepatic, or renal causes, lymphedema must be excluded using the Stemmer sign (inability to lift skin at the base of the second toe). 1, 5
Lymphedema is typically unilateral with a history of lymph node dissection or infection, and does not respond to diuretics or elevation. 2, 5