General clinical study of fluid from the abdominal cavity

In healthy people, there is a small amount of fluid in the abdominal cavity between the peritoneal sheets. In a number of diseases( cirrhosis of the liver, heart failure), the amount of ascitic fluid can be significant and reach several liters, this fluid belongs to transudates and has all its signs. Hemorrhagic exudate is found in cancerous and, more rarely, tubercular peritonitis, traumas, strangulated hernias, hemorrhagic diathesis, meleosarcoma of the peritoneum, sometimes cirrhosis of the liver. In cases of perforation of the intestine, gall bladder, the contents of the abdominal cavity may contain an admixture of bile.

For the differential diagnosis of ascites due to malignant neoplasms and ascites in chronic liver diseases, an albumin gradient is used( the difference between serum albumin concentration and that in ascites fluid).If it is below 1.1, then in more than 90% of cases, ascites is associated with carcinomatosis or tuberculosis of the peritoneum, pancreatitis or diseases of the bile duct, nephrotic syndrome, intestinal infarction or intestinal obstruction, serositis. The albumin gradient is almost always above 1.1 for liver cirrhosis, alcoholic hepatitis, massive liver metastases, fulminant hepatic insufficiency, portal thrombosis, heart failure, fatty hepatosis of pregnant women, myxedema.

The total number of leukocytes in ascites fluid in chronic liver diseases is less than 300 cells per 1 μl( in 50% of cases), neutrophilic leukocytes are less than 25%( in a third of cases).

With peritonitis of infectious etiology, the total number of leukocytes is more than 500 cells per 1 μl( sensitivity is more than 80%, specificity is 98%), neutrophilic leukocytes make up more than 50%.

At a microscopic examination, red blood cells are detected in tuberculous peritonitis, portal vein thrombosis and mesenteric vessels, peritoneal malignant tumors, traumatic injuries. A large number of white blood cells occurs with purulent peritonitis, a large number of lymphocytes - with chronic tuberculous peritonitis. The presence of atypical cells, especially in the form of clusters, is characteristic of neoplasms of the peritoneum. The specificities of ascitic fluid for various diseases are given in the table.

Criteria for diagnosing penetrating abdominal wounds according to peritoneal lavage data:

■ the number of erythrocytes more than 10 000 in 1 μl( more than 5000 in 1 μl for gunshot wounds);

■ the number of leukocytes is more than 500 in 1 μl or the presence of bile, stool, or bacteria when stained with Gram stain.

Criteria for diagnosis of obtuse abdominal injuries from peritoneal lavage data:

■ the number of red blood cells more than 100,000 in 1 μl;

■ the number of white blood cells is less than 500 in 1 μl;

■ The activity of α-amylase is more than 2 times higher than the upper limit of the norm.

Table Features of ascitic fluid for various diseases

Table Features of ascites fluid for various diseases

Criteria for the presence of urine in the abdominal cavity( in the presence of urinary tract fistulas) - the concentration of urea and creatinine in the ascitic fluid is more than 2 times higher than in serum.