Serum/ Ascites Albumin Gradient (SAAG) test

Once it is confirmed that you have ascites your doctor would perform the SAAG test to determine if the cause of ascites is non-peritoneal or peritoneal.

Non-peritoneal causes of ascites are usually associated with portal hypertension. Portal hypertension is high blood pressure in the portal vein, which carries blood to the liver from the digestive organs. 

The following symptoms are seen in portal hypertension:

• Bloody stools or black tarry stools
• Vomiting of blood
• Ascites
• Confusion and forgetfulness
• Reduced levels of white blood cells or platelets

Portal hypertension is commonly caused by cirrhosis (scarring of the liver). A person with cirrhosis may have symptoms such as:

• Loss of appetite
• Nausea
• Swelling in the feet, ankles or legs
• Fatigue
• Easy bruising or bleeding
• Weight loss
• Itchy skin
• Yellow discolouration of the skin and eyes (jaundice)
• Spider-like blood vessels on the skin
• Redness in palms
• Absent or loss of periods in women
• Loss of sex drive, breast development or testicular atrophy in men

Common peritoneal causes of ascites include peritoneal carcinomatosis (cancers that spread to the peritoneum) and peritonitis (inflammation of peritoneum). Some of the symptoms of peritonitis are:

• Abdominal pain 
• Fever
• Bloating 
• Nausea and vomiting
• Diarrhoea
• Loss of appetite
• Thirst
• Inability to pass stools or gas
• Low urine output
• Fatigue

Symptoms of peritoneal carcinomatosis include:

• Swelling of the ankles
• Ascites
• Stomach pain
• Breathing problems
• Unusual weight gain
• Loss of appetite
• Nausea
• Extreme tiredness

On the day of the test, wear loose clothing and do not take diuretics (water pills), such as spironolactone and furosemide. Tell your doctor if you are taking any medicines.

Your healthcare practitioner may order a blood test and ascitic fluid sample collection on the same day to calculate the SAAG. The blood sample will be collected from a vein in your arm.

Ascitic fluid is collected by a procedure called paracentesis. A needle or catheter is inserted into the peritoneal cavity to drain/collect the fluid sample. Here is how the paracentesis is done:

• You will be asked to lie on a bed. The doctor will examine you to find the most suitable position to insert the drain into the abdomen.
• Before inserting the drain, he/she will clean the site and give you a local anaesthetic injection to numb the area. 
• A lab technician will secure the drain tube with an adhesive dressing. The tube will have a collection bag on the other end.
• Once the required amount of fluid is withdrawn, the sample bag will be sent to the laboratory for testing.

Abnormal results:

A SAAG above 1.1 g/dL (grams per decilitre) is an indication of portal hypertension and suggests non-peritoneal causes of ascites, such as:

• Cirrhosis
• Budd-Chiari syndrome (hepatic vein obstruction)
• Fulminant hepatic failure
• Veno-occlusive disease
• Congestive heart failure
• Protein-losing enteropathy
• Nephrotic syndrome
• Malnutrition
• Ovarian tumours
• Myxoedema
• Pancreatic ascites
• Malignancy
• Biliary ascites
• Trauma

A SAAG below 1.1 g/dL is an indication of non-portal hypertension and suggests peritoneal causes of ascites, such as:

• Fungal and parasitic infections 

  • Candida
  • Histoplasma
  • Cryptococcus
  • Strongyloides
  • Schistosoma mansoni
  • Entamoeba histolytica
• Tuberculous peritonitis
• Primary peritoneal mesothelioma
• Secondary peritoneal carcinomatosis
• Systemic lupus erythematosus
• Endometriosis
• Foreign bodies (e.g., cotton and wood fibres, talc, barium, starch)
• Whipple disease (an infectious disease)
• Eosinophilic gastroenteritis
• Henoch-Schönlein purpura

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational point of view and is in no way a substitute for medical advice by a qualified doctor.