Ascites Flashcards
What is ascites?
Excessive accumulation of fluid in the abdominal cavity
- Variable amounts depending on the origin and severity of the pathology
- To be detectable on examination, must have >500mls in someone of average build
- Graded according to amount of distension
Some types are resistant to diuretics
What is the difference between an exudate an a transudate?
Transudate = increased hydrostatic pressure in veins leading to pressure gradient between vessels and abdominal cavity and the subsequent leakage of a transudative fluid
Exudate = actively secreted fluid secondary to inflammation (and resultant increased vascular permeability) or malignancy
What are the causes of transudative ascites?
- Cirrhosis*
- c. 75% of patients
- Associated with poor prognosis
Right heart failure
Splenic or portal vein thrombosis
Budd-Chiari syndrome
What are the causes of exudative ascites?
Malignancy:
- c. 15% of ascites
- GI tract (carcinoma of stomach, colon, pancreas, HCC, mets)
- Carcinoma of the ovary: Meigs’ syndrome = rare complication of ovarian cancer, leading to ascites out of proportion to the size of the tumour and (unilateral) pleural effusion
- Hodgkin’s and NH-lymphoma
Pancreatitis
TB
Hypoalbuminaemia:
- Nephrotic syndrome
- Severe malnutrition
- Protein losing enteropathy
How does ascites present?
Abdominal distension:
- +ve shifting dullness
- Weight gain
Abdominal discomfort/pain
- Esp if becomes infected
Shortness of breath
- As diaphragm gets splinted
and venous return reduces (from pressure on IVC)
- +/- concomitant pleural effusions
Peripheral oedema
Reduced appetite and nausea
Signs of underlying cause:
- ALD e.g. jaundice, alcohol Hx etc
- Malignancy e.g. masses, Virchow’s node, Ca Hx etc
How do you investigate ascites?
Clinical Ex
Look for cause:
- FBC, LFT, U+E, Clotting, TFT, Hep Abs etc
USS:
- Can detect volumes <500ml
- Also good to view other organs for origin of pathology e.g. pancreatitis, carcinomas etc
Ascitic tap:
- Insertion of a needle in the flank to drain a small amount of fluid for analysis
- Can also be done therapeutically for massive ascites (+ drains inserted to the same effect) causing respiratory distress or abdominal pain
What do you look for when assessing ascitic fluid from a tap?
ABC SAAG
Appearance:
- Clear/straw coloured = liver cirrhosis
- Cloudy = SBP, pancreatitis; perforated bowel
- Bloody = malignancy, haemorrhagic pancreatitis (often seen with Grey-Turners flank sign)
- Chylous/milk coloured = lymphoma, TB, malignancy
Biochemistry:
- Total protein = 0.3-4g/dL normal; >4g SBP/TB
- Glucose = similar to serum is normal; higher than serum level is pancreatitis
Cells (microscopy):
- RCC = none is normal; >100/microL is TB/malignancy; >100,000 microL is haemorrhage/trauma
WCC = <250microL is normal; >250 and mostly neutrophils is SBP; >250 and mostly lymphocytes is TB
- May also find Ca cells themselves
Serum ascitic albumin gradient - SAAG
- Indirect measure of portal pressure and can be used to tell if ascites is due to portal HTN i.e. if exudate vs transudate
How do you interpret the SAAG?
SAAG = (serum albumin) - (ascitic fluid albumin)
High SAAG:
- > 1.1g/dL
- ascitic fluid is a transudate i.e. caused by high portal HTN
Low SAAG:
- <1.1g/dL
- ascitic fluid is an exudate
How else can you differentiate between transudate and exudate on ascitic tap?
LDH:
- <225U/L = transudate
- > 225U/L = exudate
But SAAG is used more frequently
How do you manage ascites?
Manage underlying cause
Salt restriction:
- <90mmol/day (5.2g salt/day)
- Useful in cirrhosis, but not if other aetiologies i.e. Ca.
Diuretics:
- Spironolactone = best initial choice; monitor serum K as hyperK often limits use
- Loop diuretics = useful adjuncts, but only when max dose spiro used
Therapeutic paracentesis/drain
- Infection risk can be reduced by limiting catheter time to <6-8hrs
- Fluid replacement +/- albumin often given to combat the hypotension caused by reducing IVC pressure
TIPS - for chronic ascites
- Notable side effect is increased risk of hepatic encephalopathy
Beware:
- Long history of stable cirrhosis with acute development of ascites - must exclude HCC
What is spontaneous bacterial peritonitis and how do you prevent it?
A complication of ascites
- Thought to be caused by translocation of gut bacteria across gut wall and/or haematogenous spread
- E.coli is the most common bacteria implicated
Presents like classical peritonitis
Prevent by:
- Proper treatment of ascites =
- Empirical treatment of those with high neutrophil counts in their ascitic fluid (>250neutrophils/ml) with IV Abx and albumin
- Lactulose - to expedite gut transit time/reduce faecal stasis and time for bacteria to translocate
Subsequent prophylaxis for individuals recovering from SBP:
- Long term oral Abx e.g. norfloxacin, levofloxacin, trimethoprim etc
