Table 5:
Types of effusions
| Transudate | Exudate | Chylous | |
|---|---|---|---|
| Biochemical features | Accumulation of fluid as an ultrafiltrate of plasma | Associated with increased permeability of the capillaries leading to exudation of protein- rich fluid | Leakage of lymphatic fluid secondary to trauma or the obstructed thoracic duct or cisterna chyli, caused by malignant neoplasms including lymphomas and carcinomas |
| a. Total protein 3.0 g/dL (30 g/L) or lower | a. Total protein 3.0 g/dL (30 g/L) or more | a. Milky white fluid | |
| b. Specific gravity 1.015 or less | b. Specific gravity 1.015 or more | b. Wet preparation shows usually small free fat droplets | |
| c. Ratio of fluid lactic dehydrogenase to serum lactic dehydrogenase less than 0.6 | c. Ratio of fluid lactic dehydrogenase to serum lactic dehydrogenase more than 0.6 | ||
| d. Does not coagulate | d. May coagulate on standing | ||
| Cytologic features | Hypocellular smears Mostly mesothelial cells | Hypercellular smears Predominantly inflammatory cells with reactive mesothelial cells with or without malignant cells | The smears are rich in lymphocytes and some lipid- laden macrophages |
| Causes | 1. Congestive heart failure | 1. Malignant neoplasms | 1. Metastatic cancer |
| 2. Pulmonary atelectasis | 2. Infections, including bacterial pneumonia, lung abscess, tuberculosis, fungal infections, viral infections, and parasitic diseases | 2. Trauma, including blunt trauma and operative trauma | |
| 3. Nephrotic syndrome | 3. Collagen vascular diseases, including systemic lupus erythematosus and rheumatoid pleuritis | 3. Retroperitoneal cancers and lymphoma | |
| 4. Postpartum effusion | 4. Pulmonary embolism/infarction | 4. Tuberculosis | |
| 5. Peritoneal dialysis | 5. Some abdominal diseases, including pancreatitis, subphrenic abscess, esophageal rupture, and hepatic abscess | 5. Congenital lymphatic anomalies | |
| 6. Superior vena cava obstruction | 6. Radiotherapy | ||
| 7. Portal vein hypertension secondary to cirrhosis, schistosomiasis, and diffuse metastatic neoplasm in liver | 7. Bile peritonitis | ||
| 8. Postoperative abdominal surgery | 8. Trauma | ||
| 9. Meigs’ syndrome | 9. Myocardial infarction and post- myocardial infarction syndrome | ||
| 10. Chronic renal diseases with impaired renal function | 10. Aortic dissection | ||
| 11. Inferior vena cava hypertension | 11. Cardiac rupture | ||
| 12. Coagulation disorder and anticoagulant therapy |