Ascites

Question 1

What are ascites?

Answer 1

Abnormal accumulation of fluid within the peritoneal cavity

Question 2

What is meant by serum-ascites albumin gradient?

Answer 2

The serum-ascites albumin gradient or gap (SAAG) is a calculation to determine the cause of ascites:
SAAG = (serum albumin) − (albumin level of ascitic fluid)
- This phenomenon is the result of Starling’s forces between the fluid of the circulatory system and ascitic fluid.
- Under normal circumstances the SAAG is < 1.1 because serum oncotic pressure (pulling fluid back into circulation) is exactly counterbalanced by the serum hydrostatic pressure (which pushes fluid out of the circulatory system).
- This balance is disturbed in certain diseases (such as the Budd–Chiari syndrome, heart failure, or liver cirrhosis) that increase the hydrostatic pressure in the circulatory system.
- The increase in hydrostatic pressure causes more fluid to leave the circulation into the peritoneal space (ascites).
- The SAAG subsequently increases because there is more free fluid leaving the circulation, concentrating the serum albumin. The albumin does not move across membrane spaces easily because it is a large molecule.

Question 3

What are some causes of ascites?

Answer 3

1. SAAG >11g/L ⇒ ascitic fluid is transudative (low protein) ABCCPL
   - Portal Hypertension, cirrhosis, congestive heart failure, budd-chiari syndrome, alcohol-related liver disease, liver failure
2. SAAG <11g/L ⇒ ascitic fluid is exudative (high protein)
   - Hypoalbuminemia → may be due to nephrotic syndrome or severe malnutrition
   - Intra-abdominal Malignancy with peritoneal spread
   - Infections → eg. tuberculosis
   - Pancreatitis
   “MIPN” = malignancy, infection, pancreatitis, nephrotic syndrome

Question 4

What are the presenting symptoms/ signs of ascites?

Answer 4

1. Progressive Abdominal Distension → associated symptoms include early satiety, weight gain, dyspnoea
2. Shifting Dullness → change from dull to resonant when patient changes from supine to lateral decubitus position
3. Signs of Underlying Disease → Chronic Liver Disease (jaundice, spider naevi, palmer erythema), HF (elevated JVP), Upper Abdominal Malignancy (virchow’s node and weight loss)

Question 5

What investigations are used to diagnose/ monitor ascites?

Answer 5

1. Abdominal Ultrasound → inital study of choice if suspicion of new-onset ascites
2. Diagnostic Paracentesis/ ascitic tap → can detect any peritoneal infections
   - An ascitic tap showing a neutrophil count/polymorphonuclear leukocyte count > 250 cells/ uL would confirm a diagnosis of SBP.
   - Bleeding from gums, raised d-dimer and low fibrinogen can point to clinically apparent disseminated intravascular coagulation, which is one of the few absolute contraindications to performing paracentesis
3. Ascitic Fluid Analysis

Question 6

How are ascites managed?

Answer 6

1. Restrict Dietary Sodium
2. Spironolactone (Aldosterone Antagonist)
   - Side Effects ⇒ hyperkalaemia and gynaecomastia
3. Therapeutic Paracentesis → drainage in tense ascites
   - Give IV Albumin when doing large volume paracentesis
4. Antibiotics (SBP Prophylaxis) ⇒ ciprofloxacin or norfloxacin