Ascites is defined as collection of excess free fluid in the peritoneal cavity and it could be due to a number of different medical conditions. A proper history and clinical examination may reveal the underlying cause but still certain general and specific investigation are to be carried out in order to confirm or find out the possible etiology.
1. Urine Dipstick: It is a simple and cheap procedure that will be strongly positive for protein in nephrotic syndrome. If so, a 24 hour urine collection for protein should be undertaken; more than 3.5gm is indicative of nephrotic syndrome.
2. Complete Blood Count: Raised white cell count may indicate an infective etiology but a differential white count is more specific.
3. Urea and Electrolytes: Elevated urea and creatinine may indicate a renal etiology; however , it may also be a component of hepatorenal syndrome, which is renal impairment secondary to liver failure.
4. LFT’s : May be deranged in the presence of liver disease. The serum albumin will be able to indicate hypoalbuminaemia but the underlying cause must still be sought.
5. Chest X-ray: Findings suggestive of cardiac failure are cardiomegaly, upper venous diversion of blood, the presence of Kerley B lines, pulmonary edema and pleural effusion. Occasionally the presence of carcinoma may be suggested by a mass in the lung.
6. Ultrasound Abdomen: In addition to confirming the presence of ascites ultrasound will detect any intra abdominal masses that are not palpable on clinical examination. It may also indicate the presence of fatty deposits in the liver in the presence of cirrhosis. Dilated collateral veins may be visualized in conditions that cause obstruction of the venous outflow of the liver, including cirrhosis and Budd-Chiari syndrome.
7. Abdominal Paracentesis: Aspiration of the ascitic fluid is very useful to help determine the underlying cause. A sample should be sent to microbiology clinical chemistry and pathology.
Ascitic fluid Examinations
Chylous The milky white appearance of chylous ascites is due to obstruction of the lymphatic ducts.