Pericardial effusion is fluid accumulation in the pericardial space exceeding the physiologic amount (15-50 mL). Transudative effusions are anechoic, low CT density (<20 HU) simple fluid, while exudative effusions show internal echoes, septations, and higher CT density. Hemorrhagic effusions are characterized by hyperattenuating CT density (>40 HU) and suggest malignant, postoperative, or traumatic etiology. Large effusions may lead to cardiac tamponade: right ventricular diastolic collapse, right atrial inversion, swinging heart, and respiratory variation are pathognomonic findings. On MRI, simple fluid is hyperintense on T2-weighted sequences with variable T1 signal; signal characterization depending on fluid content aids etiologic differentiation.
Age Range
10-90
Peak Age
55
Gender
Equal
Prevalence
Common
The pericardial space normally contains 15-50 mL of serous fluid that reduces friction between the visceral and parietal pericardium. Pericardial effusion develops from increased fluid production (inflammation, infection, malignancy) or decreased reabsorption (increased venous pressure, lymphatic obstruction). Transudative effusions have low protein content and occur in heart failure, nephrotic syndrome, and hypothyroidism; they appear anechoic with homogeneous low density on imaging. Exudative effusions contain high protein and cells (infection, autoimmune, malignancy) and are characterized by internal echoes and fibrin strands. Hemorrhagic effusions show >40 HU on CT and T1 hyperintense signal on MRI due to blood products. Tamponade pathophysiology: rapid fluid accumulation exceeds pericardial compliance → intracardiac pressures increase → diastolic filling is impaired → cardiac output decreases. Slowly accumulating effusions allow pericardial stretching to tolerate up to 2000 mL, while acute 200 mL may cause tamponade.
Inward collapse of the right ventricular free wall during diastole on echocardiography is the most specific finding of cardiac tamponade, indicating that pericardial pressure exceeds right ventricular diastolic pressure. When evaluated together with right atrial systolic inversion, inferior vena cava dilation, and respiratory mitral/tricuspid flow variation, tamponade diagnosis is confirmed and urgent pericardiocentesis is indicated.
Anechoic or echogenic fluid collection between pericardial layers. Effusion volume is semi-quantitatively graded: small (<10 mm, posterior only), moderate (10-20 mm, circumferential), and large (>20 mm, circumferential). Transudative effusions are homogeneously anechoic; exudative effusions show fibrin strands and internal echoes. Hemorrhagic effusions are characterized by heterogeneous echogenicity and possible clot formation.
Report Sentence
A ... (anechoic/echogenic) effusion is noted in the pericardial space measuring ... mm at its widest posterior/circumferential extent.
Inward collapse of the right ventricular free wall during diastole is the most specific echocardiographic finding of cardiac tamponade. Diagnostic sensitivity increases when diastolic collapse duration is >1/3 of diastole. Right atrial inversion (systolic) is an earlier and more sensitive but less specific finding. The combination of both findings strongly supports tamponade physiology.
Report Sentence
Diastolic collapse of the right ventricular free wall is noted, consistent with cardiac tamponade physiology.
Free oscillation of the heart within the pericardial space in large pericardial effusion is termed 'swinging heart.' This finding correlates with electrical alternans on ECG (alternating QRS complex amplitude variation). Typically seen with >500 mL effusion and indicates high risk of tamponade development.
Report Sentence
Free oscillation of the heart within the large pericardial effusion ('swinging heart') is observed; clinical evaluation for tamponade risk is recommended.
Fluid-density material between pericardial layers on CT. Simple serous effusion shows water density (<20 HU), exudative effusion 20-40 HU, and hemorrhagic effusion >40-60 HU attenuation. Non-contrast CT is ideal for fluid density measurement, reliably distinguishing hemorrhagic from simple effusion. Accompanying pericardial thickening (>4 mm) suggests pericarditis.
Report Sentence
A fluid collection measuring ... HU in density and ... mm in thickness is noted in the pericardial space, consistent with ... (simple serous/exudative/hemorrhagic) pericardial effusion.
Pericardial thickening >4 mm and enhancement on contrast-enhanced CT suggests active pericarditis. Pericardial enhancement accompanying effusion points to exudative etiology, while absence of enhancement suggests transudative etiology. Nodular enhancement or irregular thickening on the pericardium suggests malignant pericardial disease (metastasis, mesothelioma). Prominence of pericardiophrenic branches of internal mammary arteries is an additional clue for inflammatory pericarditis.
Report Sentence
Contrast-enhanced examination demonstrates pericardial thickening of ... mm with enhancement, consistent with active pericarditis.
Pericardial fluid shows homogeneous hyperintense signal on T2-weighted sequences (simple fluid). In exudative effusions, signal intensity may be slightly decreased or heterogeneous depending on protein content. In hemorrhagic effusions, T2 signal may be variable depending on the methemoglobin stage (acute: hypointense; subacute: hyperintense; chronic: hypointense). STIR sequence is particularly valuable in demonstrating pericardial edema and inflammation by combining fat suppression.
Report Sentence
Fluid with ... (homogeneous hyperintense/heterogeneous) signal is noted in the pericardial space on T2-weighted sequences, consistent with ... (simple serous/exudative/hemorrhagic) pericardial effusion.
On T1-weighted sequences, pericardial fluid signal intensity reflects etiology. Simple serous effusion is T1 hypointense (dark), proteinaceous/exudative effusion shows intermediate signal, and hemorrhagic effusion (due to methemoglobin in subacute stage) shows T1 hyperintense (bright) signal. Pre-contrast T1 imaging is critical in differentiating hemorrhagic effusion because post-contrast T1 hyperintensity may be confused with gadolinium retention.
Report Sentence
On pre-contrast T1-weighted sequences, pericardial fluid shows ... (hypointense/intermediate/hyperintense) signal, consistent with ... (serous/exudative/hemorrhagic) content.
Enhancement of pericardial layers on late gadolinium enhancement (LGE) sequences indicates active pericarditis. Enhancement may be focal or diffuse. Absence of pericardial enhancement suggests transudative effusion or inactive pericarditis. LGE is also valuable in assessing accompanying myocarditis (epicardial pattern myocardial LGE) or pericardial mass.
Report Sentence
LGE imaging demonstrates ... (focal/diffuse) pericardial enhancement, consistent with active pericarditis.
Criteria
Low protein content (<3 g/dL), low LDH, serous fluid. Occurs in heart failure, cirrhosis, nephrotic syndrome, hypothyroidism, and post-radiation. Homogeneously anechoic on echocardiography, <20 HU on CT, T1 hypointense/T2 hyperintense on MRI.
Distinct Features
No pericardial thickening or enhancement expected. Effusion is typically symmetric and circumferential. Frequently accompanied by bilateral pleural effusion and ascites (other serous cavity effusions). Spontaneous resolution expected with treatment of the underlying cause.
Criteria
High protein content (>3 g/dL), high LDH, cellular fluid. Seen in infectious pericarditis (viral, bacterial, tuberculosis), autoimmune disease (SLE, rheumatoid arthritis), uremia, post-pericardiotomy syndrome, and Dressler syndrome.
Distinct Features
Fibrin strands, internal echoes, and septations may be seen on echocardiography. CT fluid density ranges 20-40 HU. Pericardial thickening and enhancement indicate inflammatory activity. MRI T2 STIR demonstrates pericardial edema and LGE shows active inflammation. Calcification development in tuberculous pericarditis indicates progression to constrictive pericarditis.
Criteria
Blood-containing fluid (hematocrit >50%). Seen in malignancy (lung cancer, breast cancer, lymphoma, melanoma), post-cardiac surgery/intervention, trauma, aortic dissection pericardial rupture, anticoagulant therapy complication, and tuberculosis.
Distinct Features
Heterogeneous echogenic content on echocardiography, possible clot formation (may appear as echogenic mass). CT fluid density >40-60 HU (acute blood). T1 hyperintense signal on MRI (subacute blood = methemoglobin). Hemorrhagic effusion carries rapid tamponade development risk because clot may obstruct pericardiocentesis needle and complicate drainage. In malignant hemorrhagic effusion, nodular masses and irregular enhancement on the pericardium may accompany.
Criteria
Effusion divided by fibrin strands and septations, not freely flowing. Usually develops after prior pericarditis, cardiac surgery, tuberculosis, or malignancy. Complicates percutaneous drainage.
Distinct Features
Fibrin septa and compartmentalized fluid collection on echocardiography. Failure of fluid to shift with position change indicates loculation. CT and MRI demonstrate internal septations and thickened pericardium. Surgical drainage (pericardial window or pericardiectomy) is preferred over percutaneous drainage. Tuberculous pericarditis is particularly prone to loculation and progression to constrictive pericarditis.
Distinguishing Feature
Pericardial cyst is a well-defined, thin-walled, unilocular, water-density (0-20 HU) cystic lesion separate from the pericardial space, with 70% located at the right cardiophrenic angle. Pericardial effusion is diffuse fluid collection BETWEEN pericardial layers that shifts with position. Cyst does not enhance and shows no thickening or septation.
Distinguishing Feature
Epicardial fat pad shows negative density (-50 to -100 HU) on CT with fat density. Pericardial effusion shows positive density (serous: 0-20 HU, hemorrhagic: >40 HU). On MRI, fat is T1/T2 hyperintense and loses signal on fat-suppressed sequences; fluid does not lose signal on fat suppression.
Distinguishing Feature
Pleural effusion collects in the posterior costophrenic sulcus and remains behind/lateral to the pericardium; pericardial effusion is located between pericardial layers. CT definitively separates anatomic boundaries: pleural effusion remains posterior to the descending aorta, pericardial effusion anterior ('displaced epicardial fat sign'). Axial sections clearly distinguish pleural and pericardial fluid in different compartments.
Distinguishing Feature
Constrictive pericarditis is characterized by thickened (>4 mm), fibrotic/calcified pericardium with minimal or no effusion. Unlike tamponade, diastolic filling is early rapid but late restricted ('dip-and-plateau' pattern). MRI shows thickened hypointense pericardium (fibrosis), septal bounce (ventricular interdependence) on real-time cine. Differentiation between effusion-dominant pericardial disease (effusive pericarditis) and constriction-dominant disease (constrictive pericarditis) determines treatment approach.
Urgency
emergentManagement
interventionalBiopsy
Not NeededFollow-up
Tedavi sonrası 1 hafta, 1 ay, 3 ay kontrol ekokardiyografi; tamponad sonrası yoğun bakım izlemi; rekürren efüzyonlarda perikardiyal pencere cerrahisi / Post-treatment echocardiography at 1 week, 1 month, 3 months; ICU monitoring after tamponade; pericardial window surgery for recurrent effusionsClinical significance of pericardial effusion depends on volume, accumulation rate, and etiology. Small effusions are usually asymptomatic and followed with treatment of the underlying cause. When tamponade develops, emergent pericardiocentesis is lifesaving (subxiphoid approach, echocardiography-guided). Malignant effusions have high recurrence rates, and pericardial window or pericardiodesis should be considered. Tuberculous pericarditis requires anti-tuberculosis treatment, and long-term follow-up is important due to risk of progression to constrictive pericarditis. Pericardiocentesis fluid analysis (cytology, culture, protein, LDH, ADA) should be performed for etiologic investigation.
Pericardial effusion can develop due to various causes: viral pericarditis (most common), heart failure, malignancy, uremia, hypothyroidism, autoimmune diseases, trauma, and aortic dissection. Tamponade is a life-threatening emergency requiring emergent pericardiocentesis (subxiphoid or echo-guided). Pericardial window surgery is considered for recurrent effusions. Malignant effusions indicate poor prognosis. Fluid analysis directed at etiology (cytology, culture, biochemistry) aids in diagnosis.