ASCITES, CAUSES AND DIAGNOSIS OF ASCITES

ASCITES

The pathological accumulation of fluid in the peritoneal cavity is known as ascites, It is a common complication of cirrhosis of the liver.

The mechanism of formation of ascites in liver cirrhosis is as following:
a. Sodium and water retention occurs due to stimulation of the rennin-angiotensin system that develops as a result of low perfusion pressure of the kidney in cirrhosis. This retained fluid causes portal hypertension and ultimately ascites. Nitric oxide has been postulated as a vasodilator (causing low perfusion pressure), although prostaglandins and atrial natriuretic peptide may be involved.

b. Portal hypertension exerts local hydrostatic pressure resulting in transudation of fluid in the peritoneal cavity.

c. Due to ow serum albumin in the blood, and as a result of poor synthesis by the liver, reduces the plasma osmotic pressure and its effects in transudation of fluid in the peritoneal cavity of the body.

DIFFERENTIAL DIAGNOSIS OF ASCITES

In long or short cases of ascites, the etiology of chronic liver disease should be looked at clinically by finding signs of all conditions that may be responsible for it. In one exam students got a case of ascites with underlying nephrotic syndrome; there associated features of nephrotic were syndrome. In such a condition it is better to give the differential diagnosis.

Practically after history and examination, we perform a diagnostic tap of ascitic fluid and send it in to the laboratory. According to the lab. The report’s causes of ascites may be divided into the conditions that-produce transudate or exudates. However recent causes of ascites are divided according to the Serum- Ascites Albumin Gradient (SAAG). It is the difference between serum albumin and ascitic fluid albumin. SAAG more than 1.1 g/dl strongly suggests that the cause of ascites is porta hypertension. SAAG less than 1.l g/dl indicate= non-portal hypertensive cause.

TRANSUDATE AND EXUDATE

Ascitic fluid may be exudates or transit depending upon the protein content Follo causes of exudates are the common transudate ascitic fluid. Transudate (protein < 2.5 g/dl)

1. Portal hypertension: due to

•Cirrhosis (most common)
• Fulminant hepatic failure
• Alcoholic hepatitis
• Congestive heart failure
• Constrictive pericarditis

2. Hypoalbuminemia: due to

• Nephrotic syndrome
• Protein-losing enteropathy
• Severe malnutrition

Exudate (protein> 2.5g/dl)
Infections: tuberculous peritonitis, peritonitis.
Malignancy: hepatic or peritoneal.

CAUSES OF ASCITES ACCORDING SAAG

Ascites when SAAG is> 1.1 g/dl
1. Portal hypertension (transudate)

⦁ Cirrhosis
⦁ Chronic hepatic congestion
– Right-sided heart failure
– Constrictive pericarditis
– Budd-Chiari syndrome

2. Myxedema
3. Nephrotic syndrome
Ascites when SAAG is < 1.1 g dl
1. Hypoalbuminemia (transudate).
2. Infections pyogenic or tuberculous
(exudates)
3. Malignancy (exudates)
4. Nephrotic syndrome (transudate)

CAUSES OF ASCITES ACCORDING TO THE TYPE OF ASCITIC FLUID
Chylous

Obstruction of the main lymphatic duct (e.g. by carcinoma)- chylomicrons are Straw-colored
Hemorrhagic
⦁ Malignancy
⦁ Ruptured ectopic
⦁ Hepatic obstruction
⦁ Abdominal trauma
⦁ Acute pancreatitis

STRAW COLORED

⦁ Malignancy
⦁ Cirrhosis
⦁ Infective
(Tuberculosis Primary present or secondary peritonitis)
⦁ Chronic pancreatitis
⦁ Congestive cardiac failure
⦁ Constrictive pericarditis
⦁ Meigs’ syndrome
⦁ Hypoproteinaemia

CLINICAL FEATURES OF ASCITES

• Abdominal distension with fullness in the flank
• Diffuse abdominal pain
• Features of cause (the most common cause is a chronic liver disease).
On examination

1. Eversion of umbilicus
2. Fluid thrill: when a huge ascites are present, a fluid thrill is elicited by flicking one side of the abdomen with the index finger and feeling the vibration on the other side of the abdomen with palmer surface of another hand. The thrill is also conducted through fat; to rule out this, another person or patient is asked to place the ulnar side of his hand in the middle of the abdomen vertically.

3- Shifting dullness: it is a dull area that moves or changes shape when the patient changes position. Ascites are suggested by the presence of dullness in the flanks with central abdominal resonance, Start percussion from the center of the abdomen towards the flank till the percussion note becomes dull. Keep the hand there and ask the patient to roll on the other side and percuss again, now the percussion note will be resonant as under the effect of gravity the fluid moves to the lower flank Now percuss again towards umbilicus to obtain a dull note.

ASCITIC FLUID ANALYSIS

Diagnostic paracentesis:

Appróximately 10-20 ml fluid is removed for diagnostic studies.
1. Inspection of ascitic fluid
Cause
• Cirrhosis
• Malignant disease
• Infection
Lymphatic Obstruction
• Biliary Communication

Appearance

• Clear, straw-colored
or light green
• Bloody
• Cloudy
• Heavy bile staining
• Milky white (chylous)

2. Cell count

• Normal ascitic fluid contains WBC < 500/mm’ and neutrophils < 250/mm
• Neutrophil count more than 250/mm’ strongly bacterial peritonitis whether spontaneous bacterial peritonitis (SBP) or secondary peritonitis due to perforation of abdominal viscus or appendicitis).

• Elevated WBC predominance of lymphocytes arouses suspicion of abdominal tuberculosis or peritoneal carcinomatosis.

3. Albumin and total protein

• The serum ascites albumin gradient (SAAG) is the best single test that can classify ascites into caused by portal hypertension by non-portal hypertension.

• SAAG> 1.1 g/dl strongly suggests underlying portal hypertension while SAAG <1.1 g/dl implicates non-portal hypertensive cause.

• The accuracy of SAAG is more than 95%. In about 4% of patients, there are mixed ascites due to portal hypertension and malignancy, thus high SAAG is indicative of portal hypertension but does not excludes concomitant malignancy.

• Ascitic fluid protein less than 1 g/dl predisposes
the patient to spontaneous bacterial peritonitis.

4. Culture and gram stain

To identify infection ascitic fluid culture is performed, About 5-10 ml of ascitic fluid is inoculated in a blood culture bottle at the patient’s bedside. Inoculation bedside increase sensitivity of positive culture over 85% in patients with neutrophil count >250/mm compared with routine culture in which sensitivity is 50%.
Other tests
• RBC > 50,000 / L denotes hemorrhagic ascites which usually is due to malignancy, tuberculosis or trauma.
• A pH of less than 7 suggests a bacterial infection.
• Cytology for malignant cells.
• Glucose – low in T.B. peritonitis
• Amylase – high amylase in pancreatic ascites.

ULTRASOUND ABDOMEN

It confirms the presence of ascites and distinguishes between the portal and non-portal causes of ascites. It also shows the liver architecture, size of the portal vein.

LAPAROSCOPY

Laparoscopy is really an important test in the evaluation of some patients especially those that have non-portal hypertensive ascites in the abdomen or other related areas, it also permits direct visualization and biopsy of the liver, peritoneum, and other intra-abdominal lymph nodes.

About the author: Soflay iNC
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