Ascites Flashcards
What is ascites?
An accumulation of free fluid within the peritoneal cavity that leads to abdominal distension.
What are the 2 types of ascites?
- Transudative - high SAAG
- Exudative - low SAAG
= This classification is based on the amount of protein found in the fluid.
What is SAAG?
Serum Ascites Albumin Gradient (SAAG).
Based on the amount of albumin in the ascitic fluid compared to the serum albumin (albumin measured in the blood).
Give 4 pathophysiological causes of ascites and an example for each.
- Local inflammation e.g. peritonitis.
- Leaky vessels e.g. imbalance between hydrostatic and oncotic pressures.
- Low flow e.g. cirrhosis, thrombosis, cardiac failure.
- Low protein e.g. hypoalbuminaemia.
Give 3 risk factors for ascites.
- High sodium diet
- Hepatocellular carcinoma
- Splanchnic vein thrombosis resulting in portal hypertension
Give 3 causes of transudate ascites.
- Portal hypertension (cirrhosis)
- Hepatic outflow obstruction
- Budd-Chiari syndrome
- Cardiac failure
- Tricuspid regurgitation
- Constrictive pericarditis
- Meig’s syndrome
What can cause transudative ascites?
Increased venous pressure due to cirrhosis, cardiac failure or hypoalbuminaemia.
What can cause exudative ascites?
Increased vascular permeability secondary to infection; inflammation (peritonitis) or malignancy.
Give 3 causes of exudate ascites.
- Peritoneal carcinomatosis
- Peritoneal TB
- Pancreatitis
- Nephrotic syndrome
- Lymphatic obstruction
Name the 2 main pathophysiological factors that contribute to the formation of ascites.
- High portal venous pressure.
- Low serum albumin.
Describe the pathogenesis of ascites.
- Increased intra-hepatic resistance leads to portal hypertension -> ascites.
- Systemic vasodilation leads to secretion of RAAS, NAd and ADH -> fluid retention.
- Low serum albumin also leads to ascites.
Give 3 signs of ascites.
- Flank swelling.
- Dull to percuss and shifting dullness.
- Large distended abdomen.
Diagnosis of ascites.
- Physical abdominal examination
- Presence of fluid is confirmed by demonstrating shifting dullness - Diagnostic aspiration of 10-20ml of fluid using ascitic tap for:
* Raised white cell count - indicative of bacterial peritonitis
* Gram stain and culture
* Cytology to find malignancy
* Amylase to exclude pancreatic ascites - Protein measurement of ascitic fluid from ascitic tap:
- Transudate (less bad) - low protein (< 30g/L) - transparent i.e. no/little
protein: - Portal hypertension e.g. cirrhosis
- Constrictive pericarditis
- Cardiac failure
- Budd-Chiari syndrome
- Exudate (extremely bad) - high protein (> 30g/L) - exudes protein:
- Malignancy
- Peritonitis
- Pancreatitis
- Peritoneal tuberculosis
- Nephrotic syndrome
What would you find on an abdominal examination of a patient with ascites?
SHIFTING DULLNESS.
Fullness in flanks.
Describe the physical abdominal examination procedure to check the signs for ascites.
Large distended abdomen - can be observed.
Shifting dullness - classic sign:
Percuss abdomen and observe dullness over fluid versus resonance over air. Ask the patient to roll on to one side, wait a good few seconds for fluid to settle at a new level .
Then, re-percuss on the side and observe the dullness has shifted.
